Abstract:

Variation of two simple sequence repeats (SSRs) in the leader region of the waxy gene was analyzed in a sample of 74 accessions, including Oryza sativa L. ssp. indica, japonica and wild rice ( O.rufipogon) representing a wide distribution range of amylose content (AC) in cultivated rice. Eight alleles were detected in the (CT)n motif and two alleles were resolved in the (AATT)n motif. The distribution of the alleles of the two SSRs was quite uneven as detected by the (CT)n motif. The repeat numbers of the two SSR motifs, (CT)n and (AATT)n, appeared to be inversely related such that the total length of this region was maintained. AC of the varieties was highly correlated with the length of SSRs. Differences in AC among the various SSR genotypes were statistically highly significant as analyzed using genotypes of both SSR motifs. Although the SSR variation did not seem to have obvious function in the synthesis of the starch synthase encoded by the waxy gene, the almost perfect correlation between the two SSRs and AC level could be used for quality improvement in rice breeding programs.

水稻蜡质基因引导区的两个SSR序列与直链淀粉含量的相关性
谈移芳 张启发

（华中农业大学作物遗传改良国家重点实验室，武汉430070）

摘要： 分析了蜡质基因引导区的两个简单重复序列(SSR)(CT)_n和(AATT)_n在74份水稻材料中的多态性及其与直链淀粉含量(AC)的关系。这些材料包括了籼稻(OryzasativaL.ssp.indica)、粳稻(O.sativassp.japonica)和普通野生稻(O.rufipogon)，其AC值覆盖了栽培稻AC分布的整个范围。以(CT)n作标记检测到8个等位基因，粳稻品种趋于含有重复数目较多(n≥16)的等位基因，重复次数较少(n≤14)的等位基因只出现在籼稻中。(AATT)n检测到2个等位基因，野生稻中少数植株表现出杂合性。分析表明AC与这两个SSR序列基因型高度相关，高AC(>22.0%)品种具有(CT)重复次数较少(n≤14)的等位基因；相反，除了糯米外，所有低或者中等AC的品种都有(CT)重复数较多(n≥16)的等位基因。具有重复次数较多的(AATT)₆等位基因的品种多为高AC，具有重复次数较少的(AATT)₅等位基因的品种多为低或中等AC。不同SSR基因型品种间AC差异极显著。虽然目前还不能确定这两个SSR序列在直链淀粉合成中的直接功能，SSR变异与AC间近乎完全的相关性可作为分子标记直接用于水稻的品质改良。

关键词： 微卫星DNA稻米品质；直链淀粉含量

Key words: microsatellite DNA, rice quality, amylose content