Ranftl Quirin L, Bastakis Emmanouil, Klermund Carina, Schwechheimer Claus
Plant Systems Biology, Wissenschaftszentrum Weihenstephan, Technische Universität München, Emil-Ramann-Strasse 8, 85354 Freising, Germany (Q.L.R., E.B., C.K., C.S.).
Plant Systems Biology, Wissenschaftszentrum Weihenstephan, Technische Universität München, Emil-Ramann-Strasse 8, 85354 Freising, Germany (Q.L.R., E.B., C.K., C.S.)
Plant Physiol. 2016 Apr;170(4):2295-311. doi: 10.1104/pp.15.01556. Epub 2016 Feb 1.
Leu-Leu-Met (LLM)-domain B-GATAs are a subfamily of the 30-membered GATA transcription factor family from Arabidopsis. Only two of the six Arabidopsis LLM-domain B-GATAs, i.e. GATA, NITRATE-INDUCIBLE, CARBON METABOLISM-INVOLVED (GNC) and its paralog GNC-LIKE/CYTOKININ-RESPONSIVE GATA FACTOR1 (GNL), have already been analyzed with regard to their biological function. Together, GNC and GNL control germination, greening, flowering time, and senescence downstream from auxin, cytokinin (CK), gibberellin (GA), and light signaling. Whereas overexpression and complementation analyses suggest a redundant biochemical function between GNC and GNL, nothing is known about the biological role of the four other LLM-domain B-GATAs, GATA15, GATA16, GATA17, and GATA17L (GATA17-LIKE), based on loss-of-function mutant phenotypes. Here, we examine insertion mutants of the six Arabidopsis B-GATA genes and reveal the role of these genes in the control of greening, hypocotyl elongation, phyllotaxy, floral organ initiation, accessory meristem formation, flowering time, and senescence. Several of these phenotypes had previously not been described for the gnc and gnl mutants or were enhanced in the more complex mutants when compared to gnc gnl mutants. Some of the respective responses may be mediated by CK signaling, which activates the expression of all six GATA genes. CK-induced gene expression is partially compromised in LLM-domain B-GATA mutants, suggesting that B-GATA genes play a role in CK responses. We furthermore provide evidence for a transcriptional cross regulation between these GATAs that may, in at least some cases, be at the basis of their apparent functional redundancy.
亮氨酸-亮氨酸-甲硫氨酸（LLM）结构域B型GATA蛋白是拟南芥中由30个成员组成的GATA转录因子家族的一个亚家族。拟南芥的六个LLM结构域B型GATA蛋白中，只有两个，即硝酸盐诱导的、参与碳代谢的GATA（GNC）及其旁系同源物GNC-LIKE/细胞分裂素响应GATA因子1（GNL），其生物学功能已得到分析。GNC和GNL共同控制生长素、细胞分裂素（CK）、赤霉素（GA）和光信号下游的种子萌发、变绿、开花时间和衰老过程。虽然过表达和互补分析表明GNC和GNL之间存在冗余的生化功能，但基于功能缺失突变体表型，其他四个LLM结构域B型GATA蛋白，即GATA15、GATA16、GATA17和GATA17L（GATA17-LIKE）的生物学作用尚不清楚。在这里，我们研究了拟南芥六个B型GATA基因的插入突变体，并揭示了这些基因在控制变绿、下胚轴伸长、叶序、花器官起始、副分生组织形成、开花时间和衰老中的作用。这些表型中的几种以前在gnc和gnl突变体中未被描述，或者与gnc gnl双突变体相比，在更复杂的突变体中有所增强。一些相应的反应可能由CK信号介导，CK信号激活所有六个GATA基因的表达。在LLM结构域B型GATA突变体中，CK诱导的基因表达部分受损，这表明B型GATA基因在CK反应中发挥作用。我们还提供了证据，证明这些GATA蛋白之间存在转录交叉调节，这在至少某些情况下可能是它们明显功能冗余的基础。
