Auxin production in diploid microsporocytes is necessary and sufficient for early stages of pollen development

First author: Xiaozhen Yao; Affiliations: Shanghai Normal University (上海师范大学): Shanghai, China

Corresponding author: Zhong-Nan Yang

Gametophytic development in Arabidopsis depends on nutrients and cell wall materials from sporophytic cells (孢子体细胞). However, it is not clear whether hormones and signaling molecules from sporophytic tissues are also required for gametophytic development. Herein, we show that auxin produced by the flavin monooxygenases (黄素单加氧酶) YUC2 and YUC6 in the sporophytic microsporocytes (小孢子母细胞) is essential for early stages of pollen development. The first asymmetric mitotic division (PMI; 不对称有丝分裂) of haploid microspores (小孢子) is the earliest event in male gametophyte development. Microspore development in yuc2 yuc6 double mutants arrests before PMI and consequently yuc2 yuc6 fail to produce viable pollens. Our genetic analyses reveal that YUC2 and YUC6 act as sporophytic genes for pollen formation. We further show that ectopic production of auxin in tapetum (绒毡层), which provides nutrients for pollen development, fails to rescue the sterile (不育的) phenotypes of yuc2 yuc6. In contrast, production of auxin in either microsporocytes or microspores rescued the defects of pollen development in yuc2 yuc6 double mutants. Our results demonstrate that local auxin biosynthesis in sporophytic microsporocytic cells and microspore controls male gametophyte development during the generation transition from sporophyte to male gametophyte.

拟南芥中配子体的发育取决于来自孢子体细胞的营养供给和细胞壁成分。然而，来自孢子体组织的激素和信号分子对于配子体的发育是否发挥作用还不清楚。本文显示在小孢子母细胞中由黄素单加氧酶YUC2和YUC6产生的生长素对于花粉的早期发育是必须的。单倍体的小孢子第一次不对称有丝分裂PMI是雄性配子发育过程中最早发生的。yuc2 yuc6双突变体的小孢子发育在进入PMI之前就停止，进而导致yuc2 yuc6双突变体的花粉不可育。遗传分析显示YUC2和YUC6基因作为来自孢子体的基因在花粉发育过程中发挥作用。进一步的试验表明生长素在为花粉发育提供营养的绒毡层上的异位产生并不能拯救yuc2 yuc6双突变体的不育表型。相反，在小孢子母细胞或者小孢子中的生长素能够拯救yuc2 yuc6双突变体的不育表型。本文的结果揭示了在孢子体小孢子母细胞和小孢子中的生长素合成控制孢子体向雄配子体世代转换时雄配子的发育。

通讯：杨仲南 (http://shenghuan.shnu.edu.cn/6c/74/c15218a355444/page.htm)

研究方向： 植物雄性不育及育性恢复的机理；花粉壁；叶绿体基因表达调控。

doi: https://doi.org/10.1371/journal.pgen.1007397

Journal: PLOS Genetics

Published online: 29 May, 2018

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