The Sainsbury Laboratory, University of Cambridge, Cambridge, United Kingdom.
Western Regional Research Center, USDA-ARS, Albany, United States.
Elife. 2017 Oct 24;6:e31804. doi: 10.7554/eLife.31804.
In Arabidopsis, development during flowering is coordinated by transport of the hormone auxin mediated by polar-localized PIN-FORMED1 (AtPIN1). However Arabidopsis has lost a PIN clade sister to AtPIN1, Sister-of-PIN1 (SoPIN1), which is conserved in flowering plants. We previously proposed that the AtPIN1 organ initiation and vein patterning functions are split between the SoPIN1 and PIN1 clades in grasses. Here we show that in the grass Brachypodium mutants have organ initiation defects similar to Arabidopsis , while loss of function in Brachypodium has little effect on organ initiation but alters stem growth. Heterologous expression of Brachypodium SoPIN1 and PIN1b in Arabidopsis provides further evidence of functional specificity. SoPIN1 but not PIN1b can mediate flower formation in null mutants, although both can complement a missense allele. The behavior of SoPIN1 and PIN1b in Arabidopsis illustrates how membrane and tissue-level accumulation, transport activity, and interaction contribute to PIN functional specificity.
在拟南芥中，开花期间的发育是通过激素生长素的运输来协调的，这种运输由极性定位的 PIN 形成蛋白 1（AtPIN1）介导。然而，拟南芥已经失去了与 AtPIN1 同源的 PIN 家族姐妹蛋白——Sister-of-PIN1（SoPIN1），SoPIN1 在开花植物中是保守的。我们之前提出，AtPIN1 的器官起始和叶脉模式形成功能在禾本科植物的 SoPIN1 和 PIN1 家族之间是分裂的。在这里，我们表明，在禾本科植物拟南芥中， 突变体具有与拟南芥相似的器官起始缺陷，而 Brachypodium 的 功能缺失对器官起始几乎没有影响，但改变了茎的生长。Brachypodium SoPIN1 和 PIN1b 在拟南芥中的异源表达提供了功能特异性的进一步证据。SoPIN1 但不是 PIN1b 可以在 突变体中介导花的形成，尽管两者都可以互补错义等位基因。SoPIN1 和 PIN1b 在拟南芥中的行为说明了膜和组织水平的积累、运输活性和相互作用如何有助于 PIN 功能的特异性。
