Tasselseed5 overexpresses a wound-inducible enzyme, ZmCYP94B1, that affects jasmonate catabolism, sex determination, and plant architecture in maize

First author: China Lunde; Affiliations: University of California, Berkeley (加利福尼亚大学伯克利分校): Berkeley, USA

Corresponding author: Sarah Hake 

Maize is monecious, with separate male and female inflorescences. Maize flowers are initially bisexual but achieve separate sexual identities through organ arrest. Loss-of-function mutants in the jasmonic acid (JA) pathway have only female flowers due to failure to abort silks in the tassel. Tasselseed5 (Ts5) shares this phenotype but is dominant. Positional cloning and transcriptomics of tassels identified an ectopically expressed gene in the CYP94B subfamily, Ts5 (ZmCYP94B1). CYP94B enzymes are wound inducible and inactivate bioactive jasmonoyl-L-isoleucine (JA-Ile). Consistent with this result, tassels and wounded leaves of Ts5 mutants displayed lower JA and JA-lle precursors and higher 12OH-JA-lle product than the wild type. Furthermore, many wounding and jasmonate pathway genes were differentially expressed in Ts5 tassels. We propose that the Ts5 phenotype results from the interruption of JA signaling during sexual differentiation via the upregulation of ZmCYP94B1 and that its proper expression maintains maize monoecy.

玉米是雌雄同株的植物，但具有不同的雌、雄花序。玉米的花在发育起始的时候是双性的，但随着器官的发育逐渐获得单性花的特征。JA通路的功能缺失突变体由于不能正常中止穗中须的发育而只能形成雌性花。Tasselseed5也具有这种表型，但是是显性性状。定位克隆和玉米穗的转录组鉴定了一个CYP94B亚家族中的基因ZmCYP94B1存在异位表达。CYP94B酶受到伤口诱导，并且能够使得具有生物活性的茉莉酰-L-异亮氨酸JA-lle失活。另外，相比于野生型，Ts5突变体中穗和受创伤的叶片中JA和JA-lle前体含量均有所降低，同时产生更多的12OH-JA-lle。此外，在Ts5穗中，作者还鉴定了很多伤口诱导和茉莉酸通路上的基因存在差异表达。作者提出Ts5突变体的表型可能是由于在玉米在雌雄花分化阶段ZmCYP94B1的上调阻断了JA的信号转导，而正是ZmCYP94B1基因的适当表达维持了玉米雌雄同株的表型。

通讯：Sarah Hake (https://plantandmicrobiology.berkeley.edu/profile/hake)

个人简介：1975年，格林内尔学院，生物学学士；1980年，华盛顿大学，植物生物学博士。

研究方向：1. knox同源结构域转录因子的调控作用；2. 鉴定调控玉米花序结构的基因以及干旱对于玉米花序分生组织的影响；3. 决定玉米叶片形态建成的细胞信号机制。

doi: https://doi.org/10.1038/s42003-019-0354-1

Journal: Communications Biology

Published date: March 25, 2019