Marker-assisted backcrossing to develop a fragrant rice variety from crossing between rice varieties MR269 and Basmati 370
Fragrant rice is highly demanded by Malaysian consumers. Malaysia has to import fragrant rice from fragrant rice-producing countries, which is a costly expenditure. Furthermore, traditional Basmati and Thai fragrant rice varieties are not suitable to be grown in Malaysia due to low yield and their f...
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| Format: | Thesis |
| Language: | English |
| Published: |
2017
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| Subjects: | |
| Online Access: | http://psasir.upm.edu.my/id/eprint/70340/1/FP%202017%2021%20IR.pdf |
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| Summary: | Fragrant rice is highly demanded by Malaysian consumers. Malaysia has to import fragrant rice from fragrant rice-producing countries, which is a costly expenditure. Furthermore, traditional Basmati and Thai fragrant rice varieties are not suitable to be grown in Malaysia due to low yield and their fragrance expression is specific to their native area. In order to reduce the dependency on fragrant rice import, it is crucial to develop a fragrant rice variety that is able to satisfy local consumers’ preferences and adapt to the local environment. Among the volatile compounds that contribute to fragrance in rice, 2-acetyl-1-pyrroline (2AP) plays an important role in conferring the distinct fragrances of Basmati and Jasmine rice. The accumulation of 2AP in fragrant rice is due to a mutation on chromosome 8 that results in a non-functional betaine aldehyde dehydrogenase 2 protein (BADH2). Marker-assisted backcross breeding (MABC) enables the introgression of the desired gene and accelerates the restoration of the recurrent parent genome; thus, MABC was applied in this study. MR269 variety is a high-yielding but non-fragrant rice variety and was used as the recurrent parent. Basmati 370 variety is famous for its fragrance and was used as the donor parent of the BADH2 gene to introgress the BADH2 gene into the MR269 genome. Three functional markers of the BADH2 gene were found to be polymorphic between the two parents. These functional markers were used in foreground selection to identify the desired fragrance genotype. The functional markers were used in the F1 generation and confirmed true F1 plants that were backcrossed to MR269. Chi-square analyses in the BC1F1 and BC2F1 generations showed that the functional markers segregated in a 1:1 ratio in the single gene model. All of the functional markers showed similar banding patterns for all of the backcross generations in this study. In the BC2F1 generation, aroma phenotype was evaluated. Most of the selected BC2F1 plants were scored as having a faint or moderate fragrance. Of the 324 simple sequence repeats (SSR) markers surveyed, 70 were polymorphic between the two parents and were used in background screening to determine the recovery of the recurrent parent genome. The average recovery of the recurrent parent genome in selected plants was 69.0% in the BC1F1 generation and increased to 83.6% in the BC2F1 generation. After two generations of backcrossing and one generation of self-pollination, the average recovery of the recurrent parent genome increased to 88.4% in selected BC2F2 plants with morphological phenotype similar to that of MR269. The 14 advanced fragrant rice lines that were selected from the BC2F2 generation had fragrance, and most of their morphological and agronomical characters were similar to those of MR269. These advanced fragrant rice lines can be further used in the development of a fragrant rice variety. In conclusion, this study demonstrated the successful introgression of the fragrance gene and restored the high-yielding characteristics of MR269 in advanced fragrant rice lines. It is anticipated that the new variety developed from the advanced fragrant rice lines will be utilized by local farmers and consumers in the near future. |
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