| Summary: | 碩士 === 國立嘉義大學 === 農藝學系研究所 === 99 === Rice (Oryza sativa L.) is a staple food for more than 50% of the world’s population and also is the most important crop in Taiwan. Recently, it becomes a very important issue to improve the nutrient components in rice breeding program cause to the health requirement. The purpose of this study would like to select the new rice varieties combine with aromatic rice and giant embryo characters. Besides, the molecular marker systems including ISSR (inter-simple sequence repeats), RAPD (random amplified polymorphic DNA), SCAR (sequence characterized amplified region), and SNPs (single nucleotide polymorphisms) were used in this research to assist giant embryo selection. The Aromatic Lemont (indica type, scented rice; AL) and NKY203 (japonica type, giant embryo) were used to hybridize in this study. Giant embryo rice contains high concentration of γ-aminobutyric acid (GABA) that is good for human health. The total amino acid content was further determined to clarify the correlation between giant embryo and GABA content in rice.
The cross operation and segregation lines propagation were done at Chiayi Branch Station, Tainan District Agricultural Research and Extension Station. According to the morphological observation, the grain size and shape have no significant difference between giant embryo (GE) lines and non-giant embryo (NGE) lines except the front one has larger embryo size and weight. Besides, the GE frequency segregated from F3 generation from 40% to 93% represented the genetic background was still unstable. In addition, the GABA content of brown rice is higher significantly in GE lines than in NGE lines, especially when the GE brown rice after germination pretreatment.
On the other hand, the PCR (polymerase chain reaction) products amplified from 6 sets of ISSR primers and 9 sets of RAPD primers could discriminate NKY203 and AL and probably related to the giant embryo feature. To improve the reproductivity of RAPD analysis, we eluted and sequencing all the polymorphic amplicons, then, converted them to SCAR primers for PCR. Only two SCAR primers, SCAR-RP06 and SCAR-RP17, can discriminate the parents smoothly. Unfortunately, they seem are not respect with giant embryo. In addition, we re-sequencing and compared the bands by SCAR analysis to figure out whether has SNPs existed among these sequences. It showed 7 SNPs and 3 SNPs between GE and NGE lines amplified from SCAR-RP78-2 and SCAR-RP82, respectively. Further study is necessary to clarify the correlation between these molecular markers and giant embryo. In conclusion, we selected and propagated the new rice giant embryo lines and confirmed these lines have higher GABA content than NGE lines. Besides, we developed ISSR, RAPD, SCAR, and SNPs marker systems to assist rice new varieties selection with giant embryo character. It is necessary to develop the evaluation method and molecular markers system related to rice fragrance in the future.
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