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Genetic studies on a starch biosynthesis gene, sug-h and the eating quality-related marker in rice (Oryza sativa L.)

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Authors
이윤주
Advisor
고희종
Major
농업생명과학대학 식물생산과학부(작물생명과학전공)
Issue Date
2017-02
Publisher
서울대학교 대학원
Keywords
eating qualitystarch biosynthesis
Description
학위논문 (박사)-- 서울대학교 대학원 : 식물생산과학부(작물생명과학전공), 2017. 2. 고희종.
Abstract
Rice is a major cereal crop for supply staple food, then quality improvement of rice regards as important point for production of better food. Rice eating quality has been final goal in rice breeding. Endosperm is major part of rice grain, thus, component and character of endosperm ultimately decide rice eating quality. Several studies have been reported in many countries on rice cooking and eating quality, and starch biosynthesis of endosperm. This report is composed of two parts
one is about identification of starch biosynthesis genes governing sugary endosperm phenotype, the other is genetic study of Koshihikari-specific sequence related to eating quality.
Sugary endosperm, sugary-1 (sug-1), is a mutant trait for starch biosynthesis. The sug-1 mutant plant produces the severely wrinkled seeds that were accumulated phytoglycogen-like starch. Because of poor seed phenotype which has problems in milling, sugary endosperm rice has not been commercialized despite improved digestibility and enhanced nutritional merits. Two kinds of sugary mutants, sugary-1 (sug-1) and sugary-h (sug-h) were obtained by chemical mutagenesis from Korean japonica cultivar, Hwacheong. Grains of the sug-h mutant were translucent and amber-colored, and the endosperm appeared less wrinkled than sug-1, whereas the soluble sugar content was high. These characteristics provide commercially feasible advantages to the sug-h mutant. According to genetic analysis data, the sug-h mutant phenotype was controlled by complementary interaction of two recessive genes, Isoamylase1 (OsISA1), which was reported previously, and Starch branching enzyme IIa (OsBEIIa), which was newly identified in this study. Complementation tests indicated that OsBEIIa regulated the properties of sugary endosperm. These results extend our knowledge of the mechanism of starch biosynthesis in rice endosperm, and facilitate the breeding of sugary endosperm rice for better digestibility.
Koshihikari-specific marker, named P5 is main target of this study on novel factors related to improvement of rice eating quality. The P5 marker which could be found only in Koshihikari-derived cultivars, was from the report on development of markers for eating quality evaluation. Linkage mapping using two popolations and 72 STS markers indicated that P5 marker was on the long arm of chromosome 11. Two CSSLs were used to confirm the location of P5. De novo assembly of Koshihikari was also performed to idenetify Koshihikari-specific full sequence containing P5 region. As a result, this specific seqence was about 70 kb and replaced Nipponbare sequence into Koshihikari-specific sequence. Semi-qRT-PCR results showed that only one gene was expressed among 10 predicted genes in this sequence. The NIL populations were developed and used to identify the effect of this specific sequence on eating quality. Palatability of NIL lines substitued Koshihikari-specific sequence instead of Samnam (Korean japonica cultivar with poor eating quality) was increased than Samnam, indicating that P5 sequence contributed the improvement of rice eating quality. These results will be helpful for elucidating a novel genetic factors for improvement of rice eating quailty by dissection on Koshihikari-specific sequence.
Language
English
URI
https://hdl.handle.net/10371/121042
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College of Agriculture and Life Sciences (농업생명과학대학)Dept. of Plant Science (식물생산과학부)Theses (Ph.D. / Sc.D._식물생산과학부)
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