Arabidopsis thaliana homeobox 12 (ATHB12), a homeodomain-leucine zipper protein, regulates leaf growth by promoting cell expansion and endoreduplication
Arabidopsis thaliana homeobox 12 (ATHB12), a homeodomain-leucine zipper protein, regulates leaf growth by promoting cell expansion and endoreduplication
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DOI：
10.1111/nph.12998
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发表时间：
2015-01-01
期刊：
影响因子：
9.4
通讯作者：
Cheon, Choong-Ill
中科院分区：
文献类型：
--
作者：
Hur, Yoon-Sun;Um, Ji-Hyun;Cheon, Choong-Ill
拟南芥同源框12（ATHB 12）是一个同源域亮氨酸拉链I（HD-Zip I）基因，在植物的茎和叶中高表达，受非生物胁迫诱导表达，但其在植物发育中的作用尚不清楚。为了了解它在植物发育过程中的功能，我们研究了功能丧失和获得的影响。与EAR基序阻遏结构域（SRDX）融合的ATHB 12- P-35 S：：ATHB 12 SRDX（A12 SRDX）和P-ATHB 12：：ATHB 12 SRDX-的表达减缓了叶和根的生长，而ATHB 12过表达幼苗（A12 OX）的生长加速。显微镜检查发现叶细胞的大小和数量发生了变化。A12 SRDX植株的倍性降低，伴随着细胞扩增减少和细胞数量增加。相比之下，A12 OX植物中细胞大小增加，沿着倍性增加和细胞周期开关52（CCS 52）表达升高，其是核内复制的正调节因子，表明ATHB 12促进叶细胞扩增和核内复制。ATHB 12的过表达导致拟南芥核糖体蛋白S6（AtRPS 6）的磷酸化降低，AtRPS 6是细胞生长的调节剂。此外，在放线菌酮存在下诱导ATHB 12增加了与细胞扩增相关的几个基因的表达，例如EXPANSIN A10（EXPA 10）和DWARF 4（DWF 4）。我们的研究结果强烈表明，ATHB 12作为一个积极的调节器的核内复制和细胞生长过程中的叶片发育。
Arabidopsis thaliana homeobox 12 (ATHB12), a homeodomain-leucine zipper class I (HD-Zip I) gene, is highly expressed in leaves and stems, and induced by abiotic stresses, but its role in development remains obscure. To understand its function during plant development, we studied the effects of loss and gain of function. Expression of ATHB12 fused to the EAR-motif repression domain (SRDX) - P-35S::ATHB12SRDX (A12SRDX) and P-ATHB12::ATHB12SRDX - slowed both leaf and root growth, while the growth of ATHB12-overexpressing seedlings (A12OX) was accelerated. Microscopic examination revealed changes in the size and number of leaf cells. Ploidy was reduced in A12SRDX plants, accompanied by decreased cell expansion and increased cell numbers. By contrast, cell size was increased in A12OX plants, along with increased ploidy and elevated expression of cell cycle switch 52s (CCS52s), which are positive regulators of endoreduplication, indicating that ATHB12 promotes leaf cell expansion and endoreduplication. Overexpression of ATHB12 led to decreased phosphorylation of Arabidopsis thaliana ribosomal protein S6 (AtRPS6), a regulator of cell growth. In addition, induction of ATHB12 in the presence of cycloheximide increased the expression of several genes related to cell expansion, such as EXPANSIN A10 (EXPA10) and DWARF4 (DWF4). Our findings strongly suggest that ATHB12 acts as a positive regulator of endoreduplication and cell growth during leaf development.