Gattolin Stefano, Alandete-Saez Monica, Elliott Katherine, Gonzalez-Carranza Zinnia, Naomab Erold, Powell Corinna, Roberts Jeremy A
Division of Plant Sciences, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough, Leics LE12 5RD, UK.
J Exp Bot. 2006;57(15):4225-33. doi: 10.1093/jxb/erl205. Epub 2006 Nov 10.
ARR22 (At3g04280) is a novel Type A response regulator whose function in Arabidopsis is unknown. RT-PCR analysis has shown that expression of the gene takes place in flowers and developing pods with the tissues accumulating different proportions of splice variants. Spatial analysis of expression, using ARR22::GUS plants as a marker, has revealed that the reporter protein accumulates specifically at the junction between the funiculus and the chalazal tissue. Expression can be up-regulated at this location by wounding the developing seed. A detailed analysis has failed to detect ARR22 expression at any other sites and, to support this assertion, the only evidence for tissue ablation in ARR22::Barnase plants is during seed development, with the consequence that embryo growth is attenuated. Ectopic expression of ARR22, driven by either the CaMV 35S or the pea plastocyanin (PPC) promoters, resulted in the generation of plants exhibiting extremely stunted root and shoot growth. No viable progeny could be isolated from the PPC::ARR22 transgenic lines. An RT-PCR analysis of a recently annotated gene (ARR24-At5g26594), that exhibits 66% amino acid similarity to ARR22, has shown that expression is also predominantly in floral and silique tissues. Examination of ARR24::GUS plants has revealed that the activity of the promoter is primarily restricted to pollen grains indicating that this gene is unlikely to display an overlapping function with ARR22. Analyses of individual KO lines of either ARR22 or ARR24 have failed to identify a mutant phenotype under the growth conditions employed and the double knockout ARR22/ARR24 line is also indistinguishable from wild-type plants. These results are discussed in the light of the proposed role of response regulators in plant growth and development.
ARR22（At3g04280）是一种新型的A型响应调节因子，其在拟南芥中的功能尚不清楚。逆转录聚合酶链反应（RT-PCR）分析表明，该基因在花和发育中的豆荚中表达，不同组织积累不同比例的剪接变体。以ARR22::GUS植物为标记进行表达的空间分析表明，报告蛋白特异性地积累在珠柄与合点组织的交界处。通过损伤发育中的种子，该位置的表达可被上调。详细分析未能在任何其他部位检测到ARR22的表达，为支持这一论断，在ARR22::Barnase植物中，组织消融的唯一证据是在种子发育期间，结果胚胎生长受到抑制。由花椰菜花叶病毒35S启动子或豌豆质体蓝素（PPC）启动子驱动的ARR22异位表达，导致产生根和茎生长极度矮小的植株。从PPC::ARR22转基因系中无法分离出有活力的后代。对一个最近注释的基因（ARR24-At5g26594）进行的RT-PCR分析表明，该基因与ARR22有66%的氨基酸相似性，其表达也主要在花和角果组织中。对ARR24::GUS植物的检测表明，启动子的活性主要局限于花粉粒，这表明该基因不太可能与ARR22具有重叠功能。对ARR22或ARR24的单个基因敲除系进行分析，未能在所采用的生长条件下鉴定出突变表型，ARR22/ARR24双敲除系也与野生型植物没有区别。根据响应调节因子在植物生长发育中的拟议作用对这些结果进行了讨论。
