Genetic Mapping of Giant Embryo Mutant and Varietal Variation of Rice Embryo

학위논문 (석사)-- 서울대학교 대학원 : 식물생산과학부 작물생명과학 전공, 2013. 2. 고희종.Rice embryo provides many essential nutrients for human health as well as other valuable industrial materials, and the embryo size is also positively correlated with the contents of such salutary compounds as γ-aminobutyric acid (GABA), α-tocopherol and vitamins. Thus controlling embryo size is becoming more and more important in the field of rice breeding. We obtained three giant embryo mutants derived from Hwacheongbyeo (Korean japonica cultivar) by N-methyl-N-nitrosourea (MNU). These three mutants, embryo size of all of which were larger than that of wild type (Hwacheongbyeo), were named according to different embryo size as ge-m, ge and ge-s, from the smallest to the largest, respectively. The result of allelism test among wild type, ge-m, ge and ge-s revealed that the embryo size of ge and ge-s was controlled by the same gene (GIANT EMBRYO, GE). Through GE locus sequencing of three mutants, we found that each of ge and ge-s had a point mutation in GE locus, causing amino acid substitution in the coding region, but ge-m had no sequence alteration in the locus. We performed genetic mapping of the gene controlling ge-m phenotype and identified that the gene is located in chromosome 3 between S03p28781 and RM15758 markers. In spite of high nutritional value, most of embryos, in general, are detached from grain and lost during milling process. Therefore, increasing unstripped embryo rate (UER) is important during milling process. We conducted comparative analysis on grain and embryo traits among 49 rice varieties in order to select desirable candidates of embryo rice and to collect basic data for developing high UER variety. Correlation analysis among traits collected showed that embryo dent, which in turn is expected to affect UER was positively correlated with grain width(r=0.53**) and grain area(r=0.34*), while negative correlation with grain length to width ratio(r=-0.38**), revealing that the attached shape of embryo was influenced by the shape of grain. Likewise, it was noted that the embryo dent was mainly affected by grain width, not by grain length, and embryo dent affected to the position of embryonic shoot and radicle. Daerip 1, Jinbu, Jinbo, Heugseol, Obong, Unkwang, Cheongnam, Koshihikari, Cheonghaejinmi and Boramchan showed high embryo dent. These data and the varieties identified by this study could be useful in selecting promising varieties with high UER and developing new variety of higher UER.GENERAL ABSTRACT I CONTENTS IV LIST OF TABLES VII LIST OF FIGURES VIII LIST OF ABBREVIATIONS IX CHAPTER Ⅰ : GENETIC ANALYSIS OF GIANT EMBRYO MUTANTS ABSTRACT 1 INTRODUCTION 3 MATERIALS AND METHODS 6 1. PLANT MATERIALS 6 2. PHENOTYPES EXAMINATION 6 3. DNA EXTRACTION AND PCR AMPLIFICATION 7 4. PRIMERS 7 5. γ-aminobutyric acid (GABA) CONTENT ANALYSIS 8 6. HISTOCHEMICAL ANALYSIS 8 7. SEQUENCING ALIGNMENT AND CO-SEGREGATION ANALYSIS 10 8. GENETIC ANALYSIS AND MAPPING 10 RESULTS 13 CHARACTERIZATION OF THREE GIANT EMBRYO MUTANTS 13 COMPARISON OF GABA CONTENTS 16 HISTOLOGICAL ANALYSIS 17 GENETIC ANALYSIS OF THREE GIANT EMBRYO MUTANTS 19 GIANT EMBRYO (GE) GENE SEQUENCE ALIGNMENT 21 CO-SEGREGATION TEST OF ge AND ge-s ALLELES 23 GENETIC MAPPING OF ge-m MUTANT 24 DISCUSSION 28 CHAPTER Ⅱ : VARIETAL VARIATION OF RICE EMBRYO ABSTRACT 31 INTRODUCTION 33 MATERIALS AND METHODS 35 1. VARIETIES 35 2. MEASUREMENT OF GRAIN AND EMBRYO TRAITS 35 3. STATISTICAL ANALYSIS 36 4. HISTOLOGICAL ANALYSIS OF EMBRYO 36 RESULTS 37 GRAIN AND EMBRYO TRAITS 37 CORRELATION ANALYSIS AMONG GRAIN AND EMBRYO TRAITS 43 DISCUSSION 45 REFERENCE 47 ABSTRACT IN KOREAN 50 ACKNOWLEDGEMENT 52Maste