GhL1L1 affects cell fate specification by regulating GhPIN1‐mediated auxin distribution

First author: Jiao Xu; Affiliations: Huazhong Agricultural University (中国华中农业大学): Wuhan, China

Corresponding author: Xianlong Zhang (张献龙)

Auxin is as an efficient initiator and regulator of cell fate during somatic embryogenesis (SE), but the molecular mechanisms and regulating networks of this process are not well understood. In this report, we analysed SE process induced by Leafy cotyledon1‐like 1 (GhL1L1), a NF‐YB subfamily gene specifically expressed in embryonic tissues in cotton. We also identified the target gene of GhL1L1, and its role in auxin distribution and cell fate specification during embryonic development was analysed. Overexpression of GhL1L1 accelerated embryonic cell formation, associated with an increased concentration of IAA in embryogenic calluses (ECs; 胚性愈伤组织) and in the shoot apical meristem (茎尖分生组织), corresponding to altered expression of the auxin transport gene GhPIN1. By contrast, GhL1L1‐deficient explants showed retarded (发育迟缓的) embryonic cell formation, and the concentration of IAA was decreased in GhL1L1‐deficient ECs. Disruption of auxin distribution accelerated the specification of embryonic cell fate together with regulation of GhPIN1. Furthermore, we showed that PHOSPHATASE 2AA2 (GhPP2AA2) was activated by GhL1L1 through targeting the G‐ox of its promoter, hence regulating the activity of GhPIN1 protein. Our results indicate that GhL1L1 functions as a key regulator in auxin distribution to regulate cell fate specification in cotton and contribute to the understanding of the complex process of SE in plant species.

生长素是体细胞胚胎发生SE过程中细胞命运的起始和调控因子，当该过程的调控网络仍然不是很清楚。本文研究了由棉花胚胎中特异表达的一个NF‐YB亚家族基因GhL1L1所诱导的SE过程。作者鉴定了GhL1L1的靶基因，以及其在体胚发生过程生长素分布和细胞命运决定中的作用。过表达GhL1L1会促进胚性细胞的形成，同时胚性愈伤组织和茎尖分生组织中的IAA浓度增加，这与生长素转运基因GhPIN1表达的变化相互一致。相反，GhL1L1缺陷的外植体胚性细胞形成迟缓，且胚性愈伤组织中IAA的浓度降低。扰乱生长素的分布会加速胚性细胞命运的特化以及GhPIN1的调控。此外，作者还鉴定了GhL1L1蛋白通过结合到GhPP2AA2基因启动子区的G‐ox来激活GhPP2AA2基因的表达。本文的结果揭示了GhL1L1作为棉花中生长素分布调控细胞命运决定的关键调控因子，对于我们进一步理解植物中体细胞胚胎发生的复杂过程具有促进作用。

通讯：张献龙 (http://cpst.hzau.edu.cn/szdw/jsml/js/201702/t20170221_100933.htm)

个人简介：1980.09-1984.06，华中农业大学，作物遗传育种，学士；1984.09-1987.06，华中农业大学，作物遗传育种，硕士；1987.09-1990.06，华中农业大学，作物遗传育种，博士；1993.10-1994.10，加拿大曼尼托巴大学，农学院植物科学技术系，访问学者；1998.11-1999.04，美国阿拉巴马农工大学，植物科学系，访问学者；2001.11-2002.02，英国杜伦大学，生物系，访问学者。

研究方向：棉花生物技术及育种应用研究。

doi: https://doi.org/10.1111/pbi.12947

Journal: Plant Biotechnology Journal

First Published: 13 May, 2018

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