《植物生理学报》 2012, 48(2): 147-155

优质稻米‘青香软粳’低直链淀粉含量形成分子机制的初步研究

李凌^1,*, 田麟^1,*, 王涛涛¹, 蒋其根², 罗治靖¹, 陈明姣¹, 张建中³, 张大兵¹, 袁政^1,**

1上海交通大学生命科学技术学院, 上海200240; 2上海市青浦区农业技术推广服务中心, 上海201700; 3上海市农业技术推广

通信作者：李凌；E-mail: zyuan@sjtu.edu.cn；Tel: 021-34204869

摘　要：

Waxy (Wx)基因在调控直链淀粉含量形成过程中起着重要的作用, 是稻米蒸煮食味品质的一个关键决定因素。在本 项研究中, 我们以直链淀粉含量为8.7%和10.2%的优质稻品种‘青香软粳’和‘南粳46’为主要研究对象, 初步分析并探讨了这两个优质稻品种稻米低直链淀粉形成的分子调控机理。结果显示, 虽然都为Wx-II型粳稻品种, ‘南粳46’的Wx基因在启动子-1 773位置存在AA/CT的变异, ‘南粳46’和‘青香软粳’的Wx基因在启动子+693位置具有G/A位点多态性。转录水平分析表明, 在‘南粳46’和‘青香软粳’稻米发育过程中, Wx基因的表达模式有较大的差异, 可能与其启动子序列的多态性相关, AA/CT变异处于Wx基因的转录调控区。Wx基因启动子后+693位点的多态性与已报道Wxmq多态性位点之一相同, 引起Arg158/His158的变异; 生物信息学软件分析表明, 该位点处于底物进入Wx蛋白催化中心的袋口上, Arg158/His158位点的变异可能影响到底物进入Wx蛋白催化活性中心的速率, 从而影响稻米直链淀粉的合成过程和含量。文章丰富了Wx基因多态性的研究, 为进一步验证其核苷酸变异与稻米直链淀粉含量的相关性奠定了基础

关键词：优质稻米; ‘青香软粳’; 直链淀粉含量; Wx基因; 多态性

收稿：2011-11-10   修定：2011-11-30

资助：国家自然科学基金面上项目(30971739)、上海市科委重点科技攻关项目(09391912200)和上海市农委“水稻产业技术体系建设”专项。

Preliminary Study for the Molecular Mechanism of Low Amylose Content in High-Quality Rice (Oryza sativa L.) Variety ‘Qingxiangruanjing’

LI Ling^1,*, TIAN Lin^1,*, WANG Tao-Tao¹, JIANG Qi-Gen², LUO Zhi-Jing¹, CHEN Ming-Jiao¹, ZHANG Jian-Zhong³, ZHANG Da-Bing¹, YUAN Zheng^1,**

¹School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China; ²Shanghai Qingpu District Agricultural Technology Extension and Service Center, Shanghai 201700, China; ³Shanghai Agricultural Technology Extension and Service Center, Shanghai 201103, China

Corresponding author: LI Ling; E-mail: zyuan@sjtu.edu.cn; Tel: 021-34204869

Abstract:

Waxy (Wx) gene, which is a key factor in regulating amylose content (AC), plays an important role in determining rice eating and cooking quality (ECQ). In this study, for further exploiting the underlying relationship and regulatory mechanism between the AC and ECQ, the Wx polymorphism was characterized in the high-quality rice varieties ‘Qingxiangruanjing’ and ‘Nanjing46’ with 8.7% and 10.2% AC respectively. Although all of the varieties we analyzed belong to the Wx-II japonica cultivars, the AC is different among them. Expression analysis of Wx gene in ‘Qingxiangruanjing’ and ‘Nanjing46’ indicates that their expression patterns are different, which might be correlated to the nucleotide polymorphism at nucleotide position -1 773 from the start codon in ‘Nanjing46’ variety, and the AA/CT nucleotides locate in the transcription regulatory area. While the Arg¹⁵⁸/His¹⁵⁸ polymorphism in both ‘Qingxiangruanjing’ and ‘Nanjing46’ varieties might have sophisticated effect on AC since the amino acid is located in the pocket area of the Wx protein, which may change the catalytic activity of the starch synthase for substrate and affect the AC in rice, and this mutation site also have been reported to be the one of characterizations of the Wx^mq gene. Therefore, our study enriches the research of Wx genetic polymorphism, and provides basis for further validating the relationship between rice AC and Wx gene polymorphism.

Key words: high-quality rice;‘Qingxiangruanjing’; amylose content; Wx gene; polymorphism