Plant Cellular and Molecular Biology Graduate Program, The Ohio State University, Columbus, OH, USA.
BMC Plant Biol. 2013 Jan 2;13:1. doi: 10.1186/1471-2229-13-1.
The Arabidopsis thaliana gene SPATULA (SPT), encoding a bHLH transcription factor, was originally identified for its role in pistil development. SPT is necessary for the growth and development of all carpel margin tissues including the style, stigma, septum and transmitting tract. Since then, it has been shown to have pleiotropic roles during development, including restricting the meristematic region of the leaf primordia and cotyledon expansion. Although SPT is expressed in roots, its role in this organ has not been investigated.
An analysis of embryo and root development showed that loss of SPT function causes an increase in quiescent center size in both the embryonic and postembryonic stem cell niches. In addition, root meristem size is larger due to increased division, which leads to a longer primary root. spt mutants exhibit other pleiotropic developmental phenotypes, including more flowers, shorter internodes and an extended flowering period. Genetic and molecular analysis suggests that SPT regulates cell proliferation in parallel to gibberellic acid as well as affecting auxin accumulation or transport.
Our data suggest that SPT functions in growth control throughout sporophytic growth of Arabidopsis, but is not necessary for cell fate decisions except during carpel development. SPT functions independently of gibberellic acid during root development, but may play a role in regulating auxin transport or accumulation. Our data suggests that SPT plays a role in control of root growth, similar to its roles in above ground tissues.
拟南芥基因 SPATULA（SPT），编码 bHLH 转录因子，最初因其在雌蕊发育中的作用而被鉴定。SPT 是所有心皮边缘组织（包括花柱、柱头、隔膜和传递道）生长和发育所必需的。从那时起，它在发育过程中表现出多种功能，包括限制叶原基和子叶扩张的分生组织区域。尽管 SPT 在根中表达，但它在该器官中的作用尚未被研究。
对胚胎和根发育的分析表明，SPT 功能丧失会导致胚胎和后生干细胞龛中的静止中心大小增加。此外，由于分裂增加，根分生组织的大小更大，导致主根更长。spt 突变体表现出其他多效性发育表型，包括更多的花、更短的节间和更长的开花期。遗传和分子分析表明，SPT 与赤霉素平行调节细胞增殖，同时影响生长素的积累或运输。
我们的数据表明，SPT 在拟南芥孢子体生长过程中的生长控制中发挥作用，但除了在心皮发育过程中外，对于细胞命运决定不是必需的。SPT 在根发育中独立于赤霉素发挥作用，但可能在调节生长素运输或积累中发挥作用。我们的数据表明，SPT 在控制根生长中起作用，类似于其在地上组织中的作用。
