HAF1 Modulates Circadian Accumulation of OsELF3 Controlling Heading Date Under Long-day Conditions in Rice

First author: Chunmei Zhu; Affiliations: Huazhong Agricultural University (华中农业大学): Wuhan, China

Corresponding author: Changyin Wu (吴昌银)

The ubiquitin 26S proteasome system (UPS) is critical for enabling plants to alter their proteomes to integrate internal and external signals for the photoperiodic induction (光周期诱导) of flowering. We previously demonstrated that HAF1, a C3HC4 RING domain-containing E3 ubiquitin ligase, is essential to precisely modulate the timing of Heading Date1 accumulation and to ensure appropriate photoperiodic responses under short-day conditions in rice (Oryza sativa). However, how HAF1 mediates flowering under long-day conditions remains unknown. In this study, we show that OsELF3 (EARLY FLOWERING3) is the direct substrate of HAF1 for ubiquitination in vitroand in vivo. HAF1 is required for maintaining the circadian rhythm of OsELF3 accumulation during photoperiodic responses in rice. In addition, the haf1 oself3 double mutant headed as late as oself3 plants under long-day conditions. An amino acid variation (L558S) within the interaction domain of OsELF3 with HAF1 greatly contributes to the variation in heading date among japonica rice accessions. Japonica accessions carrying the OsELF3(L) type allele are found at higher latitudes, while varieties carrying the OsELF3(S) type allele are found at lower latitudes. Taken together, our findings suggest that HAF1 precisely modulates the diurnal rhythm of OsELF3 accumulation to ensure the appropriate heading date in rice.

泛素26S蛋白酶体降解途径在植物中通过改变蛋白质组来整合内外部信号作用于开花的光周期诱导。作者在之前的研究中揭示了一个包含C3HC4 RING结构域的E3泛素连接酶HAF1对于精确调控水稻中Heading Date1的时间积累和短日照条件下的光周期响应至关重要。然而，HAF1在长日照条件下是如何介导开花调控的还不清楚。本文的研究显示早期开花蛋白OsELF3在体内或体外都是HAF1的直接泛素化底物。在水稻的光周期响应中，HAF1对于维持OsELF3的昼夜节律性积累是必需的。另外，haf1 oself3双突变体与oself3单突变体在长日照条件下开花同样延迟。在OsELF3与HAF1互作结构域一个氨基酸的变异L558S作用于不同japonica水稻品种中开花期的变异，带有OsELF3(L)等位基因型的品种分布在较高纬度区域，而带有OsELF3(S)等位基因型的品种分布在较低纬度区域。综上，本文的发现揭示了HAF1精确调控OsELF3在日间的节律积累，从而保证正确的水稻抽穗期。

通讯：吴昌银（http://lst.hzau.edu.cn/info/1025/1691.htm）

个人简介：1996年，华中农业大学，蔬菜学学士；2003年，华中农业大学，生物化学与分子生物学博士；2006-2007年，英国John Innes Centre，博士后。

研究方向：水稻功能基因组；植物成花转换；株型穗型发育生物学。

doi: https://doi.org/10.1105/tpc.18.00653

Journal: Plant Cell

First Published: 21 September, 2018

（P.S. 原文下载：链接:https://pan.baidu.com/s/1qFiSsqwlF_7JjmGMbedfhQ  密码:dmu6）