季节性因素调控小麦开花时间的分子与表观遗传机制

doi:10.13560/j.cnki.biotech.bull.1985.2024-0959

摘要/Abstract

摘要：

小麦（Triticum aestivum, AABBDD）是全球范围内重要的粮食作物之一，也是我国仅次于水稻的第二大粮食作物。小麦的广适性和生态类型多样性与其开花时间密切相关，而开花时间也是决定小麦产量及品质的一个重要的农艺性状。冬季的持续低温和春夏的长日照是确保冬小麦适时开花结实的两个关键季节性因素，小麦分别通过春化作用路径和光周期调控路径来感知并响应这两种环境信号，从而适时开花结实。本文分别对小麦春化途径和光周期调控途径进行了概述，对目前研究不足进行了分析，并对今后的研究方向进行了展望。

关键词: 春化, 光周期, 小麦开花时间调控, VRN1, PPD1

Abstract:

Wheat（Triticum aestivum, AABBDD）is one of the most important food crops in the world, and is also the second staple food crop in China. The wide adaptability and ecological diversity of wheat varieties is partly determined by their flowering time. Furthermore, flowering time is an important agronomic trait that partly determines the yield and quality of wheat grain. Prolonged cold exposure in winter（winter cold）and increasing daylengths in spring and early summer are two key seasonal factors that ensure winter wheat flowering and bearing fruit at the proper time. The vernalization and photoperiodic pathways have been evolved in winter wheat to integrate the signals of winter cold and daylength changes with developmental state, leading to the floral transition at a proper season for seed production. In this review, we summarize molecular epigenetic progresses on wheat flowering-time regulation, discuss unsolved issues as well as prospects future directions in this field.

Key words: vernalization, photoperiod, regulation of wheat flowering-time, VRN1, PPD1

牛德, 何跃辉. 季节性因素调控小麦开花时间的分子与表观遗传机制[J]. 生物技术通报, 2024, 40(10): 30-40.

NIU De, HE Yue-hui. Molecular Epigenetic Understanding of Seasonal Regulation of Flowering Time in Wheat[J]. Biotechnology Bulletin, 2024, 40(10): 30-40.

图/表 2

图1 小麦光周期信号调控成花转变的分子途径长日照条件下，光敏素感受光信号后，抑制晚间复合体（Evening Complex，EC）的功能，从而解除其对PPD1表达的抑制，PPD1促进VRN3表达，进而促进成花转变

Fig. 1 Molecular pathway for photoperiodic regulation of flowering in wheat In long days, phytochromes senses light signals and further inhibits the function of the Evening Complex（EC）, which in turn relieves the repression of PPD1 expression by EC. PPD1 further promotes VRN3 expression, thereby promoting the transition to flowering

图2 季节因素与小麦开花调控示意图图示冬小麦生长周期与一年四季（秋季9-11月、冬季12-翌年2月、春季3-5月及夏季6-8月）温度及日照长度的对应关系。我国冬小麦主产区一般于每年10-11月播种，翌年5-6月成熟收获。日照时长显示我国北方主要地区（北纬30°-北纬50°）一年中的白天时长变化趋势。温度所示1960-2016年我国北方冬小麦主产区一年中的平均气温变化趋势[103]。小麦萌发后，VRN2被光激活表达并且表达模式受生物钟调控，VRN2抑制VRN3表达；随着冬季低温，VRN1被逐渐诱导表达，从而逐渐抑制VRN2的表达；随着春季日照时间变长及温度升高，VRN3在多种因素作用下逐渐被诱导表达，VRN1-VRN3形成正反馈调控，继续抑制VRN2的表达并促使小麦逐渐从营养生长期向生殖生长期转变；随着小麦开花结实，小麦胚中VRN1、VRN2及 VRN3的表达陆续被抑制，以便开始新的生命周期

Fig. 2 Seasonal factors and flowering regulation of wheat This schematic drawing shows the relationship between the growth cycle of winter wheat and seasons（autumn, September-November; winter, December-February; spring, March-May; summer, June-August）. Winter wheat in China is typically sown in October and November, and harvested in May or June of the coming year. The daylength curve shows the variation trend of daytime in northern regions of China（30°N-50°N）during the seasons. The temperature curve shows the average temperature variation trend in the main winter-wheat production areas in China from 1960 to 2016[103]. After wheat germination, VRN2 expression was activated by light and regulated by circadian clock, VRN2 inhibited VRN3 expression. With the decrease of temperature in winter, the expression of VRN1 was gradually induced and the expression of VRN2 was gradually inhibited. With the increase of daylength and temperature in spring, VRN3 expression was gradually induced by various factors. VRN1-VRN3 constitutes a positive feedback regulation loop, which represses VRN2 expression and promotes the switch from the vegetative phase to reproduction gradually. After the fertilization following flowering, the expression of VRN1 in embryogenesis was turned off in order to start a new life cycle of winter wheat

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