The rice sucrose synthase 3 (RSUS3) localized predominantly inrice seed endosperm may play an important role in the starch filling in the milky stage of rice seed. As the genetic diversity at this locus is not known yet, forty three rice varieties/accessions were objected to amplify full sequence of the RSUS3 to examine the distribution of DNA polymorphisms. A total of 254 sequence variants, including 82, 150 and 22SNP sand indels, were successfully identified in whole length of 7,733bp sequence comprising promoter, exon and intron, and 3’ down stream non transcribed region(NTR). Eleven haplotypes were distinguishable among 43 rice varieties based on the nucleotide variation on the three defined regions (5’NTR, transcript and 3’NTR). The promoter region showed the occurrence of a base change on a cis-element which might involve a functional role of the motif in seed-specific expression. Non random process seemed to be acted in the genetic diversity of RSUS3geneamongricegermplasmusedinthisstudy. The analysis of polymorphism sites indicated a history of eleven minimum recombination mostly occurred in the transcribed region. This result might provide an insight for a clasditic approach for establishing future genetic association studies of RSUS3locus.

Sucrose synthase 3 which is a third active gene present in rice, is localized predominantly in rice endosperm. This sucrose synthase 3 may play an important role in the starch filling in the milky stage rice seed, probably involving in the starch physicochemical properties. As the genetic diversity at this locus is little informed, forty three rice consisting of japonica, indica and Oryza rufipogon were targeted to amplify full sequence of sucrose synthase 3 to examine the frequency and distribution of nucleotide polymorphism. Total of 755 all sequence variants detected, 491 single nucleotide polymorphisms (SNPs) and 264 indels were successfully identified in 7618 bp of sequence containing the sucrose synthase 3 transcript, promoter and 3' non-transcribed region. The frequency of nucleotide changes and indels were high, on average one polymorphism per 15.5 bp and one indel per 28.9 bp with 11 sequence-based haplotypes distinguishable among the varieties and lines. Both the frequency of nucleotide changes and indels were frequent in non-coding region, but rare in coding region. Sequencing a polymorphism region in the promoter showed one base change on one of cis-element from T (CATGCATA to A (CATGCACA) that might implicate in seed specificity. The presence of a high number of haplotype shared by a few varieties indicated a little information on linkage disequilibrium.

본 연구에서는 보리 습해의 원인인 과습에 의한 근권의 산소부족이 보리의 뿌리와 지상부의 amylase 및 sucrose synthase활성에 미치는 영향을 배양액의 용존산소를 1~~2ppm 의 혐기조건으로 1-7일간 처리한 3엽기 보리 유묘를 이용하여 조사하였다. 해당과정의 재료인 glucose의 공급에 관여하는 효소 중에서 전분을 분해하는 α-amylas 의 활성은 혐기조건에서 증가하나 자당을 분해하는 sucrose synthase활성은 혐기조건에서도 호기적 상태의 수준을 유지하였다. 이러한 결과는 에너지 획득과정에서의 α-amylas 의 역할이 호기조건에서보다 혐기조건에서 상대적으로 증대하는 것을 의미하는 것으로 사료된다.