PLOS Genetics:中科院植生生态所林鸿宣研究组发现赤霉素参与水稻

摘要 : 2016年10月20日，国际知名学术期刊《PLOS genetics》发表了中国科学院上海生命科学研究院植物生理生态研究所林鸿宣研究组与中国农科院作物所/深圳农业基因组所徐建龙研究组合作题为“The QTL GNP1 Encodes GA20ox1, Which Increases Grain Number and Yield by Increasing Cytokinin Activity in Rice Panicle Meristems”的研究论文。

2016年10月20日，国际知名学术期刊《PLOS genetics》发表了中国科学院上海生命科学研究院植物生理生态研究所林鸿宣研究组与中国农科院作物所/深圳农业基因组所徐建龙研究组合作题为“The QTL GNP1 Encodes GA20ox1, Which Increases Grain Number and Yield by Increasing Cytokinin Activity in Rice Panicle Meristems”的研究论文。研究工作从新的视角揭示了水稻穗型调控机制中可能存在的赤霉素与细胞分裂素的动态再平衡过程。

作为一种重要的复杂农艺性状，水稻穗型一直以来是提高水稻产量的主要育种改良目标，其中以每穗粒数尤为重要。水稻穗粒数的发育则受到穗原基活性的调控。细胞分裂素和KNOX家族转录因子被报道在水稻穗原基活性的调控中起到至关重要的作用。然而，作为另一种重要的植物激素赤霉素在这一调控过程中所扮演的角色及可能存在的调控机制却少有报道。

研究组克隆到了一个控制水稻穗粒数性状的QTL, GNP1。相较于近等基因系NIL-GNP1LT，NIL-GNP1TQ具有约56%的总穗粒数增加和约28%的实粒数增加。穗粒数的增加主要归因于次级枝梗数目的增加，并最终导致了NIL-GNP1TQ在多地小区试验中稻谷产量增幅5.7～9.6%，表明GNP1在作物高产育种中有应用价值。遗传分析验证了该基因作为一个赤霉素合成相关基因，GA20ox1，对水稻穗粒数表型有贡献。对该基因的功能分析表明在水稻穗部性状发育调控过程中赤霉素也发挥着重要的作用;进一步的分析揭示了KNOX家族转录因子介导的赤霉素和细胞分裂素参与水稻穗部性状发育调控信号间的再平衡机制。该研究为穗部性状发育的复杂调控机理研究提供了新思路，也为高产育种提供了新策略。

相关阅读：PLoS Genetics:中科院上海生科院林鸿宣研究组揭示水稻抗旱耐盐转录调控通路新成员


原文链接：

The QTL GNP1 Encodes GA20ox1, Which increases Grain Number and Yield by Increasing Cytokinin Activity in Rice Panicle Meristems

原文摘要：

Cytokinins and gibberellins (GAs) play antagonistic roles in regulating reproductive meristem activity. Cytokinins have positive effects on meristem activity and maintenance. During inflorescence meristem development, cytokinin biosynthesis is activated via a KNOX-mediated pathway. Increased cytokinin activity leads to higher grain number, whereas GAs negatively affect meristem activity. The GA biosynthesis genes GA20oxs are negatively regulated by KNOX proteins. KNOX proteins function as modulators, balancing cytokinin and GA activity in the meristem. However, little is known about the crosstalk among cytokinin and GA regulators together with KNOX proteins and how KNOX-mediated dynamic balancing of hormonal activity functions. Through map-based cloning of QTLs, we cloned a GA biosynthesis gene, Grain Number per Panicle1 (GNP1), which encodes rice GA20ox1. The grain number and yield of NIL-GNP1TQ were significantly higher than those of isogenic control (Lemont). Sequence variations in its promoter region increased the levels of GNP1 transcripts, which were enriched in the apical regions of inflorescence meristems in NIL-GNP1TQ. We propose that cytokinin activity increased due to a KNOX-mediated transcriptional feedback loop resulting from the higher GNP1 transcript levels, in turn leading to increased expression of the GA catabolism genes GA2oxs and reduced GA1 and GA3 accumulation. This rebalancing process increased cytokinin activity, thereby increasing grain number and grain yield in rice. These findings uncover important, novel roles of GAs in rice florescence meristem development and provide new insights into the crosstalk between cytokinin and GA underlying development process.

doi:10.1371/journal.pgen.1006386

作者：林鸿宣

;