Gremski Kristina, Ditta Gary, Yanofsky Martin F
Section of Cell and Developmental Biology, University of California San Diego, La Jolla, CA 92093, USA.
Development. 2007 Oct;134(20):3593-601. doi: 10.1242/dev.011510. Epub 2007 Sep 12.
Successful fertilization in plants requires the properly coordinated development of female reproductive tissues, including stigma, style, septum and transmitting tract. We have identified three closely related genes, HECATE1 (HEC1), HECATE2 (HEC2) and HECATE3 (HEC3), the expression domains of which encompass these regions of the Arabidopsis gynoecium. The HEC genes encode putative basic helix-loop-helix (bHLH) transcription factors with overlapping functionality. Depending on the amount of HEC function missing, plants exhibit varying degrees of infertility, defects in septum, transmitting tract and stigma development and impaired pollen tube growth. The observed phenotypes are similar to those reported for mutations in the SPATULA (SPT) gene, which also encodes a bHLH transcription factor required for development of the same female tissues. We show that the HEC proteins can dimerize with SPT in a yeast two-hybrid system, indicating that the HEC genes work in concert with SPT to coordinately regulate development of the female reproductive tract. Furthermore, when the HEC genes are ectopically expressed from the CaMV 35S promoter, some of the resulting transgenic plants show pin-shaped inflorescences, suggesting that the HEC genes are probably involved in auxin-mediated control of gynoecium patterning.
植物中的成功受精需要雌蕊组织（包括柱头、花柱、隔膜和传递组织）的正常协调发育。我们鉴定出了三个密切相关的基因，即HECATE1（HEC1）、HECATE2（HEC2）和HECATE3（HEC3），它们的表达域涵盖了拟南芥雌蕊的这些区域。HEC基因编码具有重叠功能的假定碱性螺旋-环-螺旋（bHLH）转录因子。根据缺失的HEC功能的量，植物表现出不同程度的不育、隔膜、传递组织和柱头发育缺陷以及花粉管生长受损。观察到的表型与SPATULA（SPT）基因突变所报道的表型相似，SPT基因也编码相同雌蕊组织发育所需的bHLH转录因子。我们发现在酵母双杂交系统中，HEC蛋白可以与SPT二聚化，这表明HEC基因与SPT协同作用以协调调节雌蕊生殖道的发育。此外，当HEC基因从CaMV 35S启动子异位表达时，一些所得转基因植物表现出针状花序，这表明HEC基因可能参与生长素介导的雌蕊模式控制。
