Bennett Tom A, Liu Maureen M, Aoyama Tsuyoshi, Bierfreund Nicole M, Braun Marion, Coudert Yoan, Dennis Ross J, O'Connor Devin, Wang Xiao Y, White Chris D, Decker Eva L, Reski Ralf, Harrison C Jill
Plant Sciences Department, University of Cambridge, Downing Street, Cambridge CB2 3EA, UK; Sainsbury Laboratory, University of Cambridge, Bateman Street, Cambridge CB2 1LR, UK.
Plant Sciences Department, University of Cambridge, Downing Street, Cambridge CB2 3EA, UK.
Curr Biol. 2014 Dec 1;24(23):2776-85. doi: 10.1016/j.cub.2014.09.054. Epub 2014 Nov 13.
Plant body plans arise by the activity of meristematic growing tips during development and radiated independently in the gametophyte (n) and sporophyte (2n) stages of the life cycle during evolution. Although auxin and its intercellular transport by PIN family efflux carriers are primary regulators of sporophytic shoot development in flowering plants, the extent of conservation in PIN function within the land plants and the mechanisms regulating bryophyte gametophytic shoot development are largely unknown.
We have found that treating gametophytic shoots of the moss Physcomitrella patens with exogenous auxins and auxin transport inhibitors disrupts apical function and leaf development. Two plasma membrane-targeted PIN proteins are expressed in leafy shoots, and pin mutants resemble plants treated with auxins or auxin transport inhibitors. PIN-mediated auxin transport regulates apical cell function, leaf initiation, leaf shape, and shoot tropisms in moss gametophytes. pin mutant sporophytes are sometimes branched, reproducing a phenotype only previously seen in the fossil record and in rare natural moss variants.
Our results show that PIN-mediated auxin transport is an ancient, conserved regulator of shoot development.
植物的身体结构在发育过程中由分生组织生长顶端的活动形成，并且在进化过程中在生命周期的配子体（n）和孢子体（2n）阶段独立辐射演化。尽管生长素及其通过PIN家族流出载体进行的细胞间运输是开花植物中孢子体茎发育的主要调节因子，但陆地植物中PIN功能的保守程度以及调节苔藓植物配子体茎发育的机制在很大程度上尚不清楚。
我们发现，用外源生长素和生长素运输抑制剂处理苔藓小立碗藓的配子体茎会破坏顶端功能和叶片发育。两种定位于质膜的PIN蛋白在叶状茎中表达，pin突变体类似于用生长素或生长素运输抑制剂处理过的植物。PIN介导的生长素运输调节苔藓配子体中的顶端细胞功能、叶起始、叶形状和茎的向性。pin突变体的孢子体有时会分枝，重现了以前仅在化石记录和罕见的天然苔藓变体中出现过的表型。
我们的结果表明，PIN介导的生长素运输是茎发育的一种古老且保守的调节因子。
