Jiao Xu Xiyan Yang Baoqi Li Lin Chen Ling Min Xianlong Zhang.2018.Plant Biotechnology Journal
Abstract
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) and in the shoot apical
meristem (SAM), corresponding to altered expression of the auxin transport gene
GhPIN1. By contrast, GhL1L1‐deficient explants showed retarded
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‐box 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.