Decoding the Grain Aroma in Rice (Oryza sativa L.): Current Progress and Prospects for Improvement

Year 2025, Volume: 31 Issue: 4, 873 - 891, 30.09.2025

Mohammad Hasanuzzaman Rani , Abu Sayeed Md Hasibuzzaman Md Hasan Sofiur Rahman

https://doi.org/10.15832/ankutbd.1573413

Abstract

Aromatic rice is a distinct category of rice because of its pleasant fragrance. Basmati and Jasmine are the most popular types of aromatic rice in the global market. Short-grain aromatic rice cultivars of South and Southeast Asia are also popular but still need to be fully explored. Many researchers have attempted to explore the origin of aromatic rice, but it is still being clarified. Researchers depicted that evolutionarily aromatic rice demonstrates a close association with the Japonica-type gene pool and could be evolved in the Himalayan foothills through a natural hybridization between domesticated Japonica and wild rice. Genetics and environment intricately interact to control the formation and accumulation of aromatic compounds in rice grain. Although several candidate gene/QTLs for grain aroma have been identified, the fgr gene mapped on chromosome 8 as BETAINE ALDEHYDE DEHYDROGENASE 2 (BADH2) encoding an oxidoreductase enzyme betaine aldehyde dehydrogenase, which oxidizes γ-aminobutyraldehyde (GAB-ald) and produces γ-aminobutyric acid (GABA), is considered as the major gene for grain aroma in rice. The loss of function of BADH2 inhibits the GABA production and enhances the conversion of GAB-ald into 2-acetyl-1-pyrroline (2AP). 2AP is considered as one of the major fragrance components in rice grain. Being a volatile component, 2AP accumulation in rice grain is highly influenced by the environmental factors and crop management practices as well. Cool temperature and low humidity are good for the accumulation of volatile fragrance components in rice grain. Low yield, lodging and disease susceptibility are major constraints in commercial cultivation. Improving the agronomic performance and disease resistance are the major breeding objectives of aromatic rice breeding. Combining conventional, mutation, and molecular breeding methods could be a better solution to develop lodging-resistant and higher-yielding aromatic rice varieties. This review focused on the current progress in aromatic rice research and prospecting the future research programs.

Keywords

aromatic rice , BADH2 , γ-aminobutyraldehyde (GAB-ald) , γ-aminobutyric acid (GABA) , 2-acetyl-1-pyrroline (2AP)

References

• Ahn S N, Bollich C N & Tanksley S D (1992). RFLP tagging of a gene for aroma in rice. Theoretical and Applied Genetics 84:825-8. https://doi.org/10.1007/BF00227391
• Ahuja S C, Panwar D V, Uma A & Gupta K R (1995). Basmati rice: the scented pearl. Basmati rice: the scented pearl. https://doi.org/10.13140/RG.2.2.26828.87681
• Amarawathi Y, Singh R, Singh A K, Singh V P, Mohapatra T, Sharma T R & Singh N K (2008). Mapping of quantitative trait loci for basmati quality traits in rice (Oryza sativa L.). Molecular Breeding 21:49-65. https://doi.org/10.1007/s11032-007-9108-8
• Andrés F, Galbraith D W, Talón M & Domingo C (2009). Analysis of PHOTOPERIOD SENSITIVITY5 sheds light on the role of phytochromes in photoperiodic flowering in rice. Plant physiology 151(2):681-690. https://doi.org/10.1104/pp.109.139097
• Anwar A, She M, Wang K, Riaz B & Ye X (2018). Biological roles of ornithine aminotransferase (OAT) in plant stress tolerance: present progress and future perspectives. International Journal of Molecular Sciences 19(11):3681. https://doi.org/10.3390/ijms19113681
• Arumugachamy S, Vairavan S, Vivekanandan P & Palanisamy S (1992). Aromatic and quality rice improvement in Tamil Nadu. Intl. Rice Res. Newsl. 17(6):11-12
• Ashokkumar S, Jaganathan D, Ramanathan V, Rahman H, Palaniswamy R, Kambale R & Muthurajan R (2020). Creation of novel alleles of fragrance gene OsBADH2 in rice through CRISPR/Cas9 mediated gene editing. PloS one 15(8): e0237018. https://doi.org/10.1371/journal.pone.0237018
• Ashraf U, Hussain S, Naveed Shahid M, Anjum S A, Kondo M, Mo Z & Tang X (2022) Alternate wetting and drying modulated physio biochemical attributes, grain yield, quality, and aroma volatile in fragrant rice. Physiologia Plantarum 174(6): e13833. https://doi.org/10.1111/ppl.13833
• Bao G, Ashraf U, Wan X, Zhou Q, Li S, Wang C, He L & Tang X (2021). Transcriptomic analysis provides insights into foliar zinc application induced upregulation in 2-acetyl-1-pyrroline and related transcriptional regulatory mechanism in fragrant rice. Journal of Agricultural and Food Chemistry. 16;69(38):11350-11360. https://doi.org/10.1021/acs.jafc.1c03655
• Basavaraj S H, Singh V K, Singh A, Singh A, Singh A, Anand D, Yadav S, Ellur R K, Singh D, Gopala Krishnan S & Nagarajan M (2010). Marker-assisted improvement of bacterial blight resistance in parental lines of Pusa RH10, a superfine grain aromatic rice hybrid. Molecular breeding, 26:293-305. https://doi.org/10.1007/s11032-010-9407-3
• Basavaraj S H, Singh V K, Singh A, Singh D, Nagarajan M, Mohapatra T, Prabhu K V & Singh AK (2009). Marker aided improvement of Pusa 6B, the maintainer parent of rice hybrid Pusa RH10, for resistance to bacterial blight. Indian Journal of Genetics and Plant Breeding, 69(01):10-16
• Bergman C J, Delgado J T, Bryant R, Grimm C, Cadwallader K R & Webb B D (2000). Rapid gas chromatographic technique for quantifying 2‐acetyl‐1‐pyrroline and hexanal in rice (Oryza sativa L.). Cereal Chemistry 77(4):454-8. https://doi.org/10.1094/CCHEM.2000.77.4.454
• Bhatti I M (1985). Lateefy, a new aromatic semidwarf rice. International Rice Research Newsletter (Philippines) Bindusree G, Natarajan P, Kalva S & Madasamy P (2017). Whole genome sequencing of Oryza sativa L. cv. Seeragasamba identifies a new fragrance allele in rice. PLoS One, 12(11):e0188920. https://doi.org/10.1371/journal.pone.0188920
• Bourgis F, Guyot R, Gherbi H, Tailliez E, Amabile I, Salse J, Lorieux M, Delseny M & Ghesquière A (2008). Characterization of the major fragance gene from an aromatic japonica rice and analysis of its diversity in Asian cultivated rice. Theoretical and Applied Genetics, 117:353-368. https://doi.org/10.1007/s00122-008-0780-9
• Bradbury L M, Fitzgerald T L, Henry R J, Jin Q & Waters D L (2005). The gene for fragrance in rice. Plant biotechnology journal 3(3):363370. https://doi.org/10.1111/j.1467-7652.2005.00131.x
• Bradbury L M, Gillies S A, Brushett D J, Waters D L & Henry R J (2008). Inactivation of an aminoaldehyde dehydrogenase is responsible for fragrance in rice. Plant molecular biology 68: 439-49. https://doi.org/10.1007/s11103-008-9381-x
• Bradbury L M, Henry R J, Jin Q, Reinke R F & Waters D L (2005). A perfect marker for fragrance genotyping in rice. Molecular Breeding, 16:279-283. https://doi.org/10.1007/s11032-005-0776-y
• Chandi G K & Sogi D S (2008). Characterization of traditional (Basmati 370) and developed (Pusa Basmati 1) basmati rice. International Journal of Food Properties, 11(4):910-918. https://doi.org/10.1080/10942910701673501
• Chan-In P, Jamjod S, Yimyam N, Rerkasem B & Pusadee T (2020). Grain quality and allelic variation of the Badh2 gene in Thai fragrant rice landraces. Agronomy, 10(6), 779. https://doi.org/10.3390/agronomy10060779
• Chen C, Cui X, Zhang P, Wang Z & Zhang J (2021). Expression of the pyrroline-5-carboxylate reductase (P5CR) gene from the wild grapevine Vitis yeshanensis promotes drought resistance in transgenic Arabidopsis. Plant Physiology and Biochemistry, 168:188-201. https://doi.org/10.1016/j.plaphy.2021.10.004
• Chen M, Wei X, Shao G, Tang S, Luo J & Hu P (2012). Fragrance of the rice grain achieved via artificial microRNA‐induced down‐regulation of OsBADH2. Plant breeding, 131(5):584-590. https://doi.org/10.1111/j.1439-0523.2012.01989.x
• Chen S, Yang Y, Shi W, Ji Q, He F, Zhang Z, Cheng Z, Liu X & Xu M (2008). Badh2, encoding betaine aldehyde dehydrogenase, inhibits the biosynthesis of 2-acetyl-1-pyrroline, a major component in rice fragrance. The Plant Cell, 20(7):1850-1861. https://doi.org/10.1105/tpc.108.058917
• Chinachanta K, Shutsrirung A, Herrmann L, Lesueur D & Pathom-Aree W (2021). Enhancement of the aroma compound 2-acetyl-1-pyrroline in thai jasmine rice (Oryza sativa) by rhizobacteria under salt stress. Biology, 10(10):1065. https://doi.org/10.3390/biology10101065
• Civáň P, Ali S, Batista-Navarro R, Drosou K, Ihejieto C, Chakraborty D, Ray A, Gladieux P & Brown T A (2019). Origin of the aromatic group of cultivated rice (Oryza sativa L.) traced to the Indian subcontinent. Genome biology and evolution, 832-843. https://doi.org/10.1093/gbe/evz039
• Costello P J & Henschke P A (2002). Mousy off-flavor of wine: Precursors and biosynthesis of the causative N-heterocycles 2 ethyltetrahydropyridine, 2-acetyltetrahydropyridine, and 2-acetyl-1-pyrroline by Lactobacillus hilgardii DSM 20176. Journal of agricultural and food chemistry 50(24):7079-7087. https://doi.org/10.1021/jf020341r
• Daygon V D, Calingacion M, Forster L C, Voss J J, Schwartz B D, Ovenden B, Alonso D E, McCouch S R, Garson M J & Fitzgerald M A (2017). Metabolomics and genomics combine to unravel the pathway for the presence of fragrance in rice. Scientific reports 7(1):8767. https://doi.org/10.1038/s41598-017-07693-9
• Desai N D, Raman S, Kukadia M U & Patel M R (1987). High-yielding aromatic rice variety GR 101. International Rice Research Newsletter (Philippines).
• Deshmukh Y, Khare P & Patra D (2016). Rhizobacteria elevate principal basmati aroma compound accumulation in rice variety. Rhizosphere, 1: 53-57. https://doi.org/10.1016/j.rhisph.2016.07.001
• improvement: Fiaz S, Ahmad S, Noor M A, Wang X, Younas A, Riaz A, Riaz A & Ali F (2019). Applications of the CRISPR/Cas9 system for rice grain quality perspectives and opportunities. International journal of molecular sciences 20(4):888. https://doi.org/10.3390/ijms20040888
• Fayaz U, Hussain S Z, Naseer B, Mahdi S S, Mir J I, Ghosh A, Jana A, Wani N R, Jabeen A, Wani F J & Manzoor S (2024). Flavor profiling and gene expression studies of indigenous aromatic rice variety (Mushk Budiji) grown at different altitudes of Highland Himalayan regions. Scientific Reports 14(1): 1010. https://doi.org/10.1038/s41598-024-51467-z
• Fitzgerald M A, McCouch S R & Hall R D (2009). Not just a grain of rice: the quest for quality. Trends in plant science 14(3):133-139. https://doi.org/10.1016/j.tplants.2008.12.004
• Fitzgerald M A, Sackville Hamilton N R, Calingacion M N, Verhoeven H A & Butardo V M (2008). Is there a second fragrance gene in rice?. Plant Biotechnology Journal 416-423. https://doi.org/10.1111/j.1467-7652.2008.00327.x
• Gao H, Jin M, Zheng X M, Chen J, Yuan D, Xin Y, Wang M, Huang D, Zhang Z, Zhou K & Sheng P (2014). Days to heading 7, a major quantitative locus determining photoperiod sensitivity and regional adaptation in rice. Proceedings of the National Academy of Sciences 111(46):16337-16342. https://doi.org/10.1073/pnas.1418204111
• Gao Q, Li G, Sun H, Xu M, Wang H, Ji J, Wang D, Yuan C & Zhao X (2020). Targeted mutagenesis of the rice FW 2.2-like gene family using the CRISPR/Cas9 system reveals OsFWL4 as a regulator of tiller number and plant yield in rice. International journal of molecular sciences 21(3):809. https://doi.org/10.3390/ijms21030809
• Gay F, Maraval I, Roques S, Gunata Z, Boulanger R, Audebert A & Mestres C (2010). Effect of salinity on yield and 2-acetyl-1-pyrroline content in the grains of three fragrant rice cultivars (Oryza sativa L.) in Camargue (France). Field crops research 117(1):154-160. https://doi.org/10.1016/j.fcr.2010.02.008
• Glaszmann J C (1987). Isozymes and classification of Asian rice varieties. Theoretical and Applied genetics 74:21-30. https://doi.org/10.1007/BF00290078
• Gouda P K, Saikumar S, Varma C M, Nagesh K, Thippeswamy S, Shenoy V, Ramesha M S & Shashidhar H E (2013). Marker‐assisted breeding of Pi‐1 and Piz‐5 genes imparting resistance to rice blast in PRR 78, restorer line of P usa RH‐10 B asmati rice hybrid. Plant Breeding, 132(1):61-69. https://doi.org/10.1111/pbr.12017
• Gui R F, Jiang H L, Ashraf U, Li S Y, Duan M Y, Pan S G, Tian H, Tang X R & Mo Z W (2022). Drought stress at flowering stage regulates photosynthesis, aroma and grain yield in fragrant rice. Applied Ecology & Environmental Research 20(3). https://doi.org/10.15666/aeer/2003_24252438
• Guo M, Zhang X, Liu J, Hou L, Liu H & Zhao X (2020). OsProDH negatively regulates thermotolerance in rice by modulating proline metabolism and reactive oxygen species scavenging. Rice 13(1):1-5. https://doi.org/10.1186/s12284-020-00422-3
• Han Y, Teng K, Nawaz G, Feng X, Usman B, Wang X, Luo L, Zhao N, Liu Y & Li R (2019). Generation of semi-dwarf rice (Oryza sativa L.) lines by CRISPR/Cas9-directed mutagenesis of OsGA20ox2 and proteomic analysis of unveiled changes caused by mutations. 3 Biotech, 9:1-7. https://doi.org/10.1007/s13205-019-1919-x
• Haowen L, Longxin H, Bin D, Shenggang P, Zhaowen M, Shuying Y, Yingbin Z & Xiangru T (2022). Epoxiconazole improved photosynthesis, yield formation, grain quality and 2-acetyl-1-pyrroline biosynthesis of fragrant rice. Rice Science 29(2):189-196. https://doi.org/10.1016/j.rsci.2022.01.007
• Hashemi F S G (2015). Genetic and molecular analyses for Oryza sativa L. Cv. Mrq74 fragrance trait through quantitative trait loci mapping using gene-based and microsatellite markers. Dissertation, University of Putra Malaysia
• Hayat S, Hayat Q, Alyemeni M N, Wani A S, Pichtel J & Ahmad A (2012). Role of proline under changing environments: a review. Plant signaling & behavior, 7(11):1456-1466. https://doi.org/10.4161/psb.21949
• He Q &Park YJ (2015). Discovery of a novel fragrant allele and development of functional markers for fragrance in rice. Molecular breeding, 35:1-10. https://doi.org/10.1007/s11032-015-0412-4
• Hien D T, Jacobs M, Angenon G, Hermans C, Thu T T & Roosens N H (2003). Proline accumulation and Δ1-pyrroline-5-carboxylate synthetase gene properties in three rice cultivars differing in salinity and drought tolerance. Plant Science 165(5):1059-1068. https://doi.org10.1016/S0168-9452(03)00301-7
• Hu X, Cui Y, Dong G, Feng A, Wang D, Zhao C, Zhang Y U, Hu J, Zeng D, Guo L & Qian Q (2019). Using CRISPR-Cas9 to generate semi dwarf rice lines in elite landraces. Scientific reports 9(1):19096. https://doi.org/10.1038/s41598-019-55757-9
• Huang T C, Huang Y W, Hung H J, Ho C T & Wu M L (2007). Δ1-Pyrroline-5-carboxylic acid formed by proline dehydrogenase from the Bacillus subtilis ssp. natto expressed in Escherichia coli as a precursor for 2-acetyl-1-pyrroline. Journal of agricultural and food chemistry 55(13):5097-102. https://doi.org/10.1021/jf0700576
• Huang T C, Teng C S, Chang J L, Chuang H S, Ho C T & Wu M L (2008). Biosynthetic mechanism of 2-acetyl-1-pyrroline and its relationship with Δ1-pyrroline-5-carboxylic acid and methylglyoxal in aromatic rice (Oryza sativa L.) callus. Journal of agricultural and food chemistry 56(16):7399-7404. https://doi.org/10.1021/jf8011739
• Huang X, Qian Q, Liu Z, Sun H, He S, Luo D, Xia G, Chu C, Li J & Fu X (2009). Natural variation at the DEP1 locus enhances grain yield in rice. Nature genetics 41(4):494-497. https://doi.org/10.1038/ng.352
• Ikehashi H (2009). Why are there indica type and japonica type in rice? History of the studies and a view for origin of two types. Rice Science, 16(1):1-3. https://doi.org/10.1016/S1672-6308(08)60050-5
• Imran M, Liu Y, Shafiq S, Abbas F, Ilahi S, Rehman N, Ahmar S, Fiaz S, Baran N, Pan S & Mo Z (2022). Transcriptional cascades in the regulation of 2‐AP biosynthesis under Zn supply in fragrant rice. Physiologia Plantarum, 174(3):e13721. https://doi.org/10.1111/ppl.13721
• Itani T, Tamaki M, Hayata Y, Fushimi T & Hashizume K (2004). Variation of 2-acetyl-1-pyrroline concentration in aromatic rice grains collected in the same region in Japan and factors affecting its concentration. Plant production science 7(2):178-183. https://doi.org/10.1626/pps.7.178
• Jezussek M, Juliano B O & Schieberle P (2002). Comparison of key aroma compounds in cooked brown rice varieties based on aroma extract dilution analyses. Journal of Agricultural and Food Chemistry 50(5):1101-1105. https://doi.org/10.1021/jf0700576
• Jin Q, Waters D, Cordeiro G M, Henry R J & Reinke R F (2003). A single nucleotide polymorphism (SNP) marker linked to the fragrance gene in rice (Oryza sativa L.). Plant Science 165(2):359-364. https://doi.org/10.1016/S0168-9452(03)00195-X
• Jodon N E (1944). Inheritance of flower fragrance and other characters in rice. Journal of the American Society of Agronomy 36(10). https://doi.org/10.2134/agronj1944.00021962003600100005x
• Jongdee B, Pantuwan G, Fukai S & Fischer K (2006). Improving drought tolerance in rainfed lowland rice: an example from Thailand. Agricultural Water Management 80(1-3):225-40. https://doi.org/10.1016/J.AGWAT.2005.07.015
• Joseph M, Gopalakrishnan S, Sharma R K, Singh V P, Singh A K, Singh N K & Mohapatra T (2004). Combining bacterial blight resistance and Basmati quality characteristics by phenotypic and molecular marker-assisted selection in rice. Molecular Breeding 13:377-387. https://doi.org/10.1023/B:MOLB.0000034093.63593.4c
• Kaikavoosi K, Kad T D, Zanan R L & Nadaf A B (2015). 2-Acetyl-1-pyrroline augmentation in scented indica rice (Oryza sativa L.) varieties through Δ 1-pyrroline-5-carboxylate synthetase (P5CS) gene transformation. Applied biochemistry and biotechnology 177:1466-1479. https://doi.org/10.1007/s12010-015-1827-4
• Khan G H, Shikari A B, Vaishnavi R, Najeeb S, Padder B A, Bhat Z A, Parray G A, Bhat M A, Kumar R & Singh N K (2018). Marker-assisted introgression of three dominant blast resistance genes into an aromatic rice cultivar Mushk Budji. Scientific Reports 8(1):4091. https://doi.org/10.1038/s41598-018-22246-4
• Khandagale K S, Chavhan R & Nadaf A B (2020). RNAi-mediated down regulation of BADH2 gene for expression of 2-acetyl-1-pyrroline in non-scented indica rice IR-64 (Oryza sativa L.). 3 Biotech, 10(4):145. https://doi.org/10.1007/s13205-020-2131-8
• Khush G S & Juliano B O (1985). Rice grain quality and marketing. Breeding for high-yielding rices of excellent cooking and eating quality. IRRI, Manila pp. 61-69
• Kishor D S, Seo J, Chin J H & Koh H J (2020). Evaluation of whole-genome sequence, genetic diversity, and agronomic traits of Basmati rice (Oryza sativa L.). Frontiers in Genetics 11:86. https://10.3389/fgene.2020.00086 Kovach M J, Calingacion M N, Fitzgerald M A & McCouch S R (2009). The origin and evolution of fragrance in rice (Oryza sativa L.). Proceedings of the National Academy of Sciences 106(34):14444-14449. https://doi.org/10.1073/pnas.09040771
• Li J Y, Wang J & Zeigler R S (2014). The 3,000 rice genomes project: new opportunities and challenges for future rice research. Gigascience, 3(1):2047-17X. https://doi.org/10.1186/2047-217X-3-8
• Li M, Ashraf U, Tian H, Mo Z, Pan S, Anjum S A, Duan M & Tang X (2016). Manganese-induced regulations in growth, yield formation, quality characters, rice aroma and enzyme involved in 2-acetyl-1-pyrroline biosynthesis in fragrant rice. Plant Physiology and Biochemistry 103:167-75. https://doi.org/10.1016/j.plaphy.2016.03.009
• Li M, Li X, Zhou Z, Wu P, Fang M, Pan X, Lin Q, Luo W, Wu G & Li H (2016). Reassessment of the four yield-related genes Gn1a, DEP1, GS3, and IPA1 in rice using a CRISPR/Cas9 system. Frontiers in plant science, 7:377. https://doi.org/10.3389/fpls.2016.00377
• Li Y, Fan C, Xing Y, Yun P, Luo L, Yan B, Peng B, Xie W, Wang G, Li X & Xiao J (2014). Chalk5 encodes a vacuolar H+-translocating pyrophosphatase influencing grain chalkiness in rice. Nature genetics 46(4):398-404. https://doi.org/10.1038/ng.2923
• Liu J M, Mei Q, Xue C Y, Wang Z Y, Li D P, Zhang Y X & Xuan Y H (2021). Mutation of G‐protein γ subunit DEP1 increases planting density and resistance to sheath blight disease in rice. Plant Biotechnology Journal 19(3):418. https://doi.org/10.1111/pbi.13500
• Liu J M, Park S J, Huang J, Lee E J, Xuan Y H, Je B I, Kumar V, Priatama R A, Raj K V, Kim S H & Min M K (2016). Loose Plant Architecture1 (LPA1) determines lamina joint bending by suppressing auxin signalling that interacts with C-22-hydroxylated and 6-deoxo brassinosteroids in rice. Journal of experimental botany 67(6):1883-1895. https://doi.org/10.1093/jxb/erw002
• Liu X, Huang Z, Li Y, Xie W, Li W, Tang X, Ashraf U, Kong L, Wu L, Wang S & Mo Z (2020). Selenium-silicon (Se-Si) induced modulations in physio-biochemical responses, grain yield, quality, aroma formation and lodging in fragrant rice. Ecotoxicology and Environmental Safety 196:110525. https://doi.org/10.1016/j.ecoenv.2020.110525
• Liu Y, Xu C, Zhu Y, Zhang L, Chen T, Zhou F, Chen H & Lin Y (2018). The calcium‐dependent kinase OsCPK24 functions in cold stress responses in rice. Journal of integrative plant biology 60(2):173-88. https://doi.org/10.1111/jipb.12614
• Lorieux M, Petrov M, Huang N, Guiderdoni E & Ghesquière A (1996). Aroma in rice: genetic analysis of a quantitative trait. Theoretical and Applied Genetics 93:1145-1151. https://doi.org/10.1007/BF00230138
• Luo H, Duan M, Kong L, He L, Chen Y, Wang Z & Tang X (2021). The regulatory mechanism of 2-Acetyl-1-Pyrroline biosynthesis in fragrant Rice(Oryza sativa L.) under different soil moisture contents. Frontiers in Plant Science 12:772728. https://doi.org/10.3389/fpls.2021.772728
• Luo H, Duan M, Xing P, Xie H & Tang X (2022). Foliar application of procyanidins enhanced the biosynthesis of 2-acetyl-1-pyrroline in aromatic rice (Oryza sativa L.). BMC Plant Biology 22(1):1-9. https://doi.org/10.1186/s12870-022-03775-7
• Luo H, Zhang T, Zheng A, He L, Lai R, Liu J, Xing P & Tang X (2020). Exogenous proline induces regulation in 2-acetyl-1-pyrroline (2-AP) biosynthesis and quality characters in fragrant rice (Oryza sativa L.). Scientific Reports 10(1):13971. https://doi.org/10.1038/s41598-02070984-1
• Ma L, Kong F, Sun K, Wang T & Guo T (2021). From classical radiation to modern radiation: past, present, and future of radiation mutation breeding. Frontiers in Public Health 9:768071. https://doi.org/10.3389/fpubh.2021.768071
• Meyer R S & Purugganan M D (2013). Evolution of crop species: genetics of domestication and diversification. Nature reviews genetics 14(12):840–852. https://doi.org/10.1038/nrg3605
• Mezl V A& Knox W E (1976). Properties and analysis of a stable derivative of pyrroline-5-carboxylic acid for use in metabolic studies. Analytical Biochemistry 74(2):430-440. https://doi.org/10.1016/0003-2697(76)90223-2
• growth and Miao C, Xiao L, Hua K, Zou C, Zhao Y, Bressan R A & Zhu J K (2018). Mutations in a subfamily of abscisic acid receptor genes promote rice productivity. Proceedings of the National Academy of Sciences 115(23):6058-6063. https://doi.org/10.1073/pnas.1804774115
• Mo Z, Lei S, Ashraf U, Khan I, Li Y, Pan S, Duan M, Tian H & Tang X (2017). Silicon fertilization modulates 2-acetyl-1-pyrroline content, yield formation and grain quality of aromatic rice. Journal of Cereal Science 75:17-24. https://doi.org/10.1016/j.jcs.2017.03.014
• Mo Z, Li W, Pan S, Fitzgerald TL, Xiao F, Tang Y, Wang Y, Duan M, Tian H & Tang X (2015). Shading during the grain filling period increases 2-acetyl-1-pyrroline content in fragrant rice. Rice 8:1-10. https://doi.org/10.1186/s12284-015-0040-y
• Mo Z, Tang Y, Ashraf U, Pan S, Duan M, Tian H, Wang S & Tang X (2019). Regulations in 2-acetyl-1-pyrroline contents in fragrant rice are associated with water-nitrogen dynamics and plant nutrient contents. Journal of cereal science 88:96-102. https://doi.org/10.1016/j.jcs.2019.05.013
• Monggoot S, Sookwong P, Mahatheeranont S & Meechoui S (2014). Influence of single nutrient element on 2-acetyl-1-pyrroline contents in Thai fragrant rice (Oryza sativa L.) cv. Khao DawkMali 105 grown under soilless conditions. In Proceedings of the 26th Annual Meeting of the Thai Society for Biotechnology and International Conference. pp. 642-647. Chiang Rai: Mae Fah Luang University. Napasintuwong O (2012). Survey of recent innovations in aromatic rice. https://doi.org/10.22004/ag.econ.135770
• Ni D, Zhang S, Chen S, Xu Y, Li L, Li H, Wang Z, Cai X, Li Z & Yang J (2011) Improving cooking and eating quality of Xieyou57, an elite indica hybrid rice, by marker-assisted selection of the Wx locus. Euphytica 179:355-362. https://doi.org/10.1007/s10681-011-0377-2
• Oka H I & Morishima H (1982). Phylogenetic differentiation of cultivated rice, XXIII. Potentiality of wild progenitors to evolve the indica and japonica types of rice cultivars. Euphytica 31:41-50. https://doi.org/10.1007/BF00028305
• Okpala N E, Potcho M P, An T, Ahator S D, Duan L & Tang X (2020). Low temperature increased the biosynthesis of 2-AP, cooked rice elongation percentage and amylose content percentage in rice. Journal of Cereal Science 93:102980. https://doi.org/10.1016/j.jcs.2020.102980
• Ootsuka K, Takahashi I, Tanaka K, Itani T, Tabuchi H, Yoshihashi T, Tonouchi A & Ishikawa R (2014). Genetic polymorphisms in Japanese fragrant landraces and novel fragrant allele domesticated in northern Japan. Breeding science 115-124. https://doi.org/10.1270/jsbbs.64.115
• Pachauri V, Mishra V, Mishra P, Singh A K, Singh S, Singh R & Singh N K (2014). Identification of candidate genes for rice grain aroma by combining QTL mapping and transcriptome profiling approaches. Cereal Research Communications 42:376-388. https://doi.org/10.1556/CRC.42.2014.3.2
• Pachauri V, Singh M K, Singh A K, Singh S, Shakeel N A, Singh V P & Singh N K (2010). Origin and genetic diversity of aromatic rice varieties, molecular breeding and chemical and genetic basis of rice aroma. Journal of Plant Biochemistry and Biotechnology, 19:127-143. https://doi.org/10.1007/BF03263333
• Peng B, Zuo Y H, Hao Y L, Peng J, Kong D Y, Peng Y, Nassirou T Y, He L L, Sun Y F, Liu L, Pang R H (2018). Studies on aroma gene and its application in rice genetics and breeding. Jour. of Plant Stud. https://doi.org/10.5539/jps.v7n2p29
• Phitaktansakul R, Kim K W, Aung K M, Maung T Z, Min M H, Somsri A, Lee W, Lee S B, Nam J, Kim S H & Lee J (2022). Multi-omics analysis reveals the genetic basis of rice fragrance mediated by betaine aldehyde dehydrogenase 2. Journal of Advanced Research 42:303314. https://doi.org/10.1016/j.jare.2021.12.004
• Poonlaphdecha J, Maraval I, Roques S, Audebert A, Boulanger R, Bry X & Gunata Z (2012). Effect of timing and duration of salt treatment during growth of a fragrant rice variety on yield and 2-acetyl-1-pyrroline, proline, and GABA levels. Journal of agricultural and food chemistry 60(15):3824-3830. https://doi.org/10.1021/jf205130y
• 2-acetyl-1-pyrroline, Potcho P M, Okpala N E, Korohou T, Imran M, Kamara N, Zhang J, Aloryi K D & Tang X (2021). Nitrogen sources affected the biosynthesis of cooked rice elongation and amylose content in rice. Plos one, 16(7):e0254182. https://doi.org/10.1371/journal.pone.0254182
• Pradhan S K, Bose L K & Mani S C (2006). Basmati type restorers and maintainers for two cytosterile lines of rice. Indian journal of genetics and plant breeding 66(04): 335–336
• Prittesh P, Avnika P, Kinjal P, Jinal H N, Sakthivel K & Amaresan N (2020). Amelioration effect of salt-tolerant plant growth-promoting bacteria on growth and physiological properties of rice (Oryza sativa) under salt-stressed conditions. Archives of Microbiology 202:2419 2428. https://doi.org/10.1007/s00203-020-01962-4
• Prodhan Z H, Faruq G, Rashid K A & Taha R M (2017). Effects of temperature on volatile profile and aroma quality in rice. International Journal of Agriculture and Biology 19(5):1065-1072. https://doi.org/10.17957/IJAB/15.0385
• Prodhan Z H & Qingyao S H (2020). Rice aroma: A natural gift comes with price and the way forward. Rice Science 27(2):86-100. https://doi.org/10.1016/j.rsci.2020.01.001
• Raina M, Salgotra R K, Pandotra P, Rathour R & Singh K (2019). Genetic enhancement for semi-dwarf and bacterial blight resistance with enhanced grain quality characteristics in traditional Basmati rice through marker-assisted selection. Comptes rendus biologies 342(56):142-153. https://doi.org/10.1016/j.crvi.2019.04.004
• Reddy V D & Reddy GM (1987). Genetic and biochemical basis of scent in rice (Oryza sativa L.). Theoretical and applied genetics 73: 699700. https://doi.org/10.1007/BF00260778
• Renuka N, Barvkar V T, Ansari Z, Zhao C, Wang C, Zhang Y & Nadaf A B (2022). Co-functioning of 2AP precursor amino acids enhances 2-acetyl-1-pyrroline under salt stress in aromatic rice (Oryza sativa L.) cultivars. Scientific Reports 12(1):3911. https://doi.org/10.1038/s41598-022-07844-7 Saini S S & Kumar I (1979). Advances in breeding high yielding scented rice vareties. Oryza.
• Sánchez E, Ruiz J M & Romero L (2002). Proline metabolism in response to nitrogen toxicity in fruit of French Bean plants (Phaseolus vulgaris L. cv Strike). Scientia Horticulturae 93(3-4):225-233. https://doi.org/10.1016/S0304-4238(01)00342-9
• Sang T & Ge S (2007). The puzzle of rice domestication. Journal of Integrative Plant Biology 49(6):760-768. https://doi.org/10.1111/j.17447909.2007.00510.x
• Sansenya S & Wechakorn K (2021). Effect of rainfall and altitude on the 2‐acetyl‐1‐pyrroline and volatile compounds profile of black glutinous rice (Thai upland rice). Journal of the Science of Food and Agriculture 101(14):5784-5791. https://doi.org/10.1002/jsfa.11227
• Sashankar P, Chidambaranathan P, Anandan A & Sathyanarayana N (2024). Downregulation of badh2 gene is responsible for aroma in Kon Joha rice (Oryza sativa L.) of Assam. The Nucleus 67(3): 483-495. https://doi.org/10.1007/s13237-024-00476-4
• Shan Q, Zhang Y, Chen K, Zhang K & Gao C (2015). Creation of fragrant rice by targeted knockout of the Os BADH 2 gene using TALEN technology. Plant biotechnology journal 13(6):791-800. https://doi.org/10.1111/pbi.12312
• Shao G, Tang S, Chen M, Wei X, He J, Luo J, Jiao G, Hu Y, Xie L & Hu P (2013). Haplotype variation at Badh2, the gene determining fragrance in rice. Genomics 101(2):157-162. https://doi.org/10.1016/j.ygeno.2012.11.010
• Shao G, Xie L, Jiao G, Wei X, Sheng Z, Tang S & Hu P (2017). CRISPR/CAS9-mediated editing of the fragrant gene Badh2 in rice. Chinese Journal of Rice Science 31(2):216-222. https://doi.org/10.16819/j.1001-7216.2017.6098
• Shao G N, Tang A, Tang S Q, Luo J, Jiao G A, Wu J L & Hu P S (2011). A new deletion mutation of fragrant gene and the development of three molecular markers for fragrance in rice. Plant breeding 130(2):172-176. https://doi.org/10.1111/j.1439-0523.2009.01764.x
• Sharma A, Srivastava A, Singh S, Mishra S, Mohan S, Singh A, Singh A K, Jaiswal H K (2021). Aromatic Rice of India: It’s Types and Breeding Strategies. London, UK: IntechOpen.
• Shelp B J, Bozzo G G, Trobacher C P, Zarei A, Deyman K L & Brikis C J (2012). Hypothesis/review: contribution of putrescine to 4aminobutyrate (GABA) production in response to abiotic stress. Plant Science 193:130-135. https://doi.org/10.1016/j.plantsci.2012.06.001
• Shen L, Hua Y, Fu Y, Li J, Liu Q, Jiao X, Xin G, Wang J, Wang X, Yan C & Wang K (2017). Rapid generation of genetic diversity by multiplex CRISPR/Cas9 genome editing in rice. Science China Life Sciences 60:506-515. https://doi.org/10.1007/s11427-017-9008-8
• Shi W, Yang Y, Chen S & Xu M (2008). Discovery of a new fragrance allele and the development of functional markers for the breeding of fragrant rice varieties. Molecular breeding 22:185-192. https://doi.org/10.1007/s11032-008-9165-7
• Shi Y, Zhao G, Xu X & Li J (2014). Discovery of a new fragrance allele and development of functional markers for identifying diverse fragrant genotypes in rice. Molecular breeding 33:701-708. https://doi.org/10.1007/s11032-013-9986-x
• Shuochen J, Lihe Z, Fenqin H, Xiangru T & Bin D (2023). Zinc supplementation and light intensity affect 2-acetyl-1-pyrroline (2AP) formation in fragrant rice. BMC Plant Biology 1; 23(1):194. https://doi.org/10.1186/s12870-022-03954-6
• Siangliw M, Toojinda T, Tragoonrung S & Vanavichit A (2003). Thai jasmine rice carrying QTLch9 (Sub QTL) is submergence tolerant. Annals of Botany 91(2):255-261. https://doi.org/10.1093/aob/mcf123
• Siddiq E A, Vemireddy L R & Nagaraju J (2012). Basmati rices: genetics, breeding and trade. Agricultural Research 1:25-36. https://doi.org/10.1007/s40003-011-0011-5
• Singh A K, Gopalakrishnan S, Singh V P, Prabhu K V, Mohapatra T, Singh N K, Sharma T R, Nagarajan M, Vinod K K, Singh D & Singh U D (2011). Marker assisted selection: a paradigm shift in Basmati breeding. Indian Journal of Genetics and Plant Breeding 71(2):120.
• Singh A K, Krishnan S G, Nagarajan M, Vinod K, Bhowmick P, Atwal S, Seth R, Chopra N, Chander S, Singh V & Prabhu KV (2014). Variety Pusa Basmati 1509. Indian J Genet Pl Br 74:123
• Singh A K, Singh V K, Singh A, Ellur R K, Pandian R T, Gopala Krishnan S, Singh U D, Nagarajan M, Vinod K K & Prabhu K V (2015). Introgression of multiple disease resistance into a maintainer of Basmati rice CMS line by marker assisted backcross breeding. Euphytica, 203:97-107. https://doi.org/10.1007/s10681-014-1267-1
• Singh R K, Singh U S, Khush G S & Rohilla R (2000). Genetics and biotechnology of quality traits in aromatic rices. Aromatic rices, 5:47-70.
• Singh V, Singh A K, Mohapatra T & Ellur R K (2018). Pusa Basmati 1121–a rice variety with exceptional kernel elongation and volume expansion after cooking. Rice 11:1-10. https://doi.org/10.1186/s12284-018-0213-6
• Somrith B (1996). Khao Dawk Mali 105: Problems, research efforts and future prospects. Report of the INGER Monitoring Visit on Fine Grain Aromatic Rice in India, Iran, Pakistan and Thailand. IRRI, Manila pp. 102-111
• Song X J, Huang W, Shi M, Zhu M Z & Lin H X (2007). A QTL for rice grain width and weight encodes a previously unknown RING-type E3 ubiquitin ligase. Nature genetics 39(5):623-630. https://doi.org/10.1038/ng2014 Srivastava D, Shamim M, Mishra A, Yadav P, Kumar D, Pandey P, Khan N A & Singh K N (2019). Introgression of semi-dwarf gene in Kalanamak rice using marker-assisted selection breeding. Current Science 116(4):597-603. https://www.jstor.org/stable/27137902
• Supapoj N, Boonyawit C, Jongdee B, Voravat O, Chamarerk V, Phengrat J, Suriyaarunroj D, Kotchasatit A, Kotchasatit U, Sattayakul K & Mekwatanakarn P (2009). RD33 (Hawm Ubon 80) rice variety. Thai Rice Research Journal Szabados L & Savouré A (2010.) Proline: a multifunctional amino acid. Trends in plant science 15(2):89-97. https://doi.org/10.1016/j.tplants.2009.11.009
• Székely G, Ábrahám E, Cséplő Á. Ri ó G, Zsi mond L, Csiszár J, Ayaydin F, Strizhov N, Jásik J, Schmelzer E, Koncz C & Szabados L (2008). Duplicated P5CS genes of Arabidopsis play distinct roles in stress regulation and developmental control of proline biosynthesis. The Plant Journal 53:11-28. https://doi.org/10.1111/j.1365-313X.2007.03318.x
• Tian Z, Qian Q, Liu Q, Yan M, Liu X, Yan C, Liu G, Gao Z, Tang S, Zeng D & Wang Y (2009). Allelic diversities in rice starch biosynthesis lead to a diverse array of rice eating and cooking qualities. Proceedings of the National Academy of Sciences 106(51):21760-21765. https://doi.org/10.1073/pnas.0912396106
• Tsuzuki E & Shimokawa E (1990). Inheritance of aroma in rice. Euphytica 46:157-159. https://doi.org/10.1007/BF00022309
• Usman B, Nawaz G, Zhao N, Liu Y & Li R (2020). Generation of high yielding and fragrant rice (Oryza sativa L.) lines by CRISPR/Cas9 targeted mutagenesis of three homoeologs of cytochrome P450 gene family and OsBADH2 and transcriptome and proteome profiling of revealed changes triggered by mutations. Plants 9(6):788. https://doi.org/10.3390/plants9060788
• Vanavichit A, Kamolsukyeunyong W, Siangliw M, Siangliw J L, Traprab S, Ruengphayak S, Chaichoompu E, Saensuk C, Phuvanartnarubal E, Toojinda T & Tragoonrung S (2018). Thai Hom Mali Rice: Origin and breeding for subsistence rainfed lowland rice system. Rice 11:112. https://doi.org/10.1186/s12284-018-0212-7
• Vemireddy L R, Noor S, Satyavathi V V, Srividhya A, Kaliappan A, Parimala S R, Bharathi P M, Deborah D A, Rao K S, Shobharani N & Siddiq E A (2015). Discovery and mapping of genomic regions governing economically important traits of Basmati rice. BMC plant biology 15:1-9. https://doi.org/10.1186/s12870-015-0575-5
• Vemireddy L R, Tanti B, Lahkar L & Shandilya Z M (2021). Aromatic rices: Evolution, genetics and improvement through conventional breeding and biotechnological methods. Molecular Breeding for Rice Abiotic Stress Tolerance and Nutritional Quality 341-357. https://doi.org/10.1002/9781119633174.ch18
• Verma D K & Srivastav P P (2018). Introduction to rice aroma, flavor, and fragrance. Science and Technology of Aroma, Flavor, and Fragrance in Rice. pp. 21-52. https://doi.org/10.1201/b22468
• Verma, D K, Mahato D K & Srivastav P P (2018). Aromatic Rice from Different Countries: An Overview. In Science and Technology of Aroma, Flavor, and Fragrance in Rice (Verma, DK, and Srivastav, PP Eds.). Apple Academic Press. https://doi.org/10.1201/b22468
• Wan X Y, Wan J M, Jiang L, Wang J K, Zhai H Q, Weng J F, Wang H L, Lei C L, Wang J L, Zhang X & Cheng Z J (2006). QTL analysis for rice grain length and fine mapping of an identified QTL with stable and major effects. Theoretical and Applied Genetics 112:1258-1270. https://doi.org/10.1007/s00122-006-0227-0
• Wang C H, Zheng X M, Xu Q, Yuan X P, Huang L, Zhou H F, Wei X H & Ge S (2014). Genetic diversity and classification of Oryza sativa with emphasis on Chinese rice germplasm. Heredity 112(5):489-96. https://doi.org/10.1038/hdy.2013.130
• Wang S, Wu K, Yuan Q, Liu X, Liu Z, Lin X, Zeng R, Zhu H, Dong G, Qian Q & Zhang G (2012). Control of grain size, shape and quality by OsSPL16 in rice. Nature genetics 44(8):950-954. https://doi.org/10.1038/ng.2327
• Wu B, Yun P, Zhou H, Xia D, Gu Y, Li P, Yao J, Zhou Z, Chen J, Liu R & Cheng S (2022). Natural variation in WHITE-CORE RATE 1 regulates redox homeostasis in rice endosperm to affect grain quality. The Plant Cell 34(5):1912-1932. https://doi.org/10.1093/plcell/koac057
• Wu Y P, Pu C H, Lin H Y, Huang H Y, Huang Y C, Hong C Y, Chang M C & Lin Y R (2015). Three novel alleles of FLOURY ENDOSPERM2 (FLO2) confer dull grains with low amylose content in rice. Plant Science 233: 44-52. https://doi.org/10.1016/j.plantsci.2014.12.011
• Xie W, Ashraf U, Zhong D, Lin R, Xian P, Zhao T, Feng H, Wang S, Duan M, Tang X & Mo Z (2019). Application of γ‐aminobutyric acid (GABA) and nitrogen regulates aroma biochemistry in fragrant rice. Food Science & Nutrition 7(11):3784-3796. https://doi.org/10.1002/fsn3.1240
• Xie W, Kong L, Ma L, Ashraf U, Pan S, Duan M, Tian H, Wu L, Tang X & Mo Z (2020). Enhancement of 2-acetyl-1-pyrroline (2AP) concentration, total yield, and quality in fragrant rice through exogenous γ-aminobutyric acid (GABA) application. Journal of Cereal Science, 91:102900. https://doi.org/10.1016/j.jcs.2019.102900
• Xie W, Li Y, Li Y, Ma L, Ashraf U, Tang X, Pan S, Tian H & Mo Z (2021). Application of γ-aminobutyric acid under low light conditions: effects on yield, aroma, element status, and physiological attributes of fragrant rice. Ecotoxicology and Environmental Safety 213:111941. https://doi.org/10.1016/j.ecoenv.2021.111941
• Xu R, Yang Y, Qin R, Li H, Qiu C, Li L, Wei P & Yang J (2016). Rapid improvement of grain weight via highly efficient CRISPR/Cas9mediated multiplex genome editing in rice. Journal of Genetics and Genomics 43(8):529-532. https://doi.org/10.1016/j.jgg.2016.07.003
• Yang S C (1988). Development of rice variety Tainung 70. Chung-hua nung yeh yen chiu. Journal of agricultural research of China. Yoshihashi T, Huong N T & Inatomi H (2002). Precursors of 2-acetyl-1-pyrroline, a potent flavor compound of an aromatic rice variety. Journal of agricultural and food chemistry 50(7):2001-4. https://doi.org/10.1021/jf011268s
• Yoshihashi T, Huong N T, Surojanametakul V, Tungtrakul P & Varanyanond W (2005). Effect of storage conditions on 2–Acetyl‐1–pyrroline content in aromatic rice variety, khao dawk mali 105. Journal of food science 70(1):S34-37. https://doi.org/10.1111/j.13652621.2005.tb09061.x
• Zeng Y, Wen J, Zhao W, Wang Q & Huang W (2020). Rational improvement of rice yield and cold tolerance by editing the three genes OsPIN5b, GS3, and OsMYB30 with the CRISPR–Cas9 system. Frontiers in plant science 10:1663. https://doi.org/10.3389/fpls.2019.01663
• Zhao D S, Li Q F, Zhang C Q, Zhang C, Yang Q Q, Pan L X, Ren X Y, Lu J, Gu M H & Liu Q Q (2018). GS9 acts as a transcriptional activator to regulate rice grain shape and appearance quality. Nature Communications 9(1):1240. https://doi.org/10.1038/s41467-018-03616-y
• Zinati Z & Delavari A (2019). Identification of candidate genes related to aroma in rice by analyzing the microarray data of highly aromatic and nonaromatic recombinant inbred line bulks. BioTechnologia. Journal of Biotechnology Computational Biology and Bionanotechnology 100(3).https://doi.org/10.5114/bta.2019.87582
• Zou J, Zhang S, Zhang W, Li G, Chen Z, Zhai W, Zhao X, Pan X, Xie Q& Zhu L (2006). The rice HIGH‐TILLERING DWARF1 encoding an ortholog of Arabidopsis MAX3 is required for negative regulation of the outgrowth of axillary buds. The Plant Journal, 48(5):687-698. https://doi.org/10.1111/j.1365-313X.2006.02916.x