水稻品种不同，开花的早晚时期也有所不同。日本一个研究小组在2月24日出版的美国《国家科学院院刊》（PNAS）上报告说，水稻花期早晚是由负责调节成花素的基因决定的。
世界各地栽培的水稻都有适应当地气候的开花时期。日本奈良尖端科学技术研究生院大学的研究人员在2007年就发现了诱导花芽形成的植物激素——成花素。在最新研究中，他们又分析了世界各地64个品种的水稻，结果发现，基因“Hd1”负责调节水稻中成花素的量，合成成花素量最多的水稻品种开花时期要比成花素量最少的品种早100天以上。
研究人员认为，从人类开始栽培水稻以来，“Hd1”基因为适应不同的环境发生了不同的变化，导致不同的水稻品种合成成花素的量不同。今后若能人为控制水稻的开花时期，水稻的产量就有可能提高。（生物谷Bioon.com）
生物谷推荐原始出处：
PNAS，doi: 10.1073/pnas.0812092106，Yasuyuki Takahashi，Ko Shimamoto
Variations in Hd1 proteins, Hd3a promoters, and Ehd1 expression levels contribute to diversity of flowering time in cultivated rice
Yasuyuki Takahashia, Kosuke M. Teshimab, Shuji Yokoia,1, Hideki Innanb and Ko Shimamotoa,2
aLaboratory of Plant Molecular Genetics, Nara Institute of Science and Technology, Ikoma, Nara 630-0101, Japan; and
bThe Graduate University for Advanced Studies, Hayama, Kanagawa 240-0193, Japan
Abstract
Rice is a facultative short-day plant, and molecular genetic studies have identified the major genes involved in short-day flowering. However, the molecular mechanisms promoting the diversity of flowering time in cultivated rice are not known. We used a core collection of 64 rice cultivars that represent the genetic diversity of 332 accessions from around the world and studied the expression levels and polymorphisms of 6 genes in the short-day flowering pathway. The RNA levels of Heading date 3a (Hd3a), encoding a floral activator, are highly correlated with flowering time, and there is a high degree of polymorphism in the Heading date 1 (Hd1) protein, which is a major regulator of Hd3a expression. Functional and nonfunctional alleles of Hd1 are associated with early and late flowering, respectively, suggesting that Hd1 is a major determinant of variation in flowering time of cultivated rice. We also found that the type of Hd3a promoter and the level of Ehd1 expression contribute to the diversity in flowering time and Hd3a expression level. We evaluated the contributions of these 3 factors by a statistical analysis using a simple linear model, and the results supported our experimental observations.
