The Arabidopsis ATHB-8 HD-zip protein acts as a differentiation-promoting transcription factor of the vascular meristems
The Arabidopsis ATHB-8 HD-zip protein acts as a differentiation-promoting transcription factor of the vascular meristems
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DOI：
10.1104/pp.126.2.643
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发表时间：
2001-06-01
期刊：
影响因子：
7.4
通讯作者：
Morelli, G
中科院分区：
文献类型：
--
作者：
Baima, S;Possenti, M;Morelli, G
ATB-8、ATB-9、ATB-14、ATB-15和IFL 1/REV是小同源结构域-亮氨酸拉链家族的成员，其基因的特征在于在血管组织中表达。ATHB-8，由生长素正调控的基因（Baima et al.，1995），被认为是受伤后血管再生期间原形成层细胞和形成层的早期标记。在这里，我们证明，虽然形成的维管系统不受影响的athb 8突变体，异位表达的ATHB-8在拟南芥植物中增加了木质部组织的生产。特别地，对转基因植物的仔细解剖学分析表明ATHB-8的过表达促进维管细胞分化。原形成层细胞先分化为初生木质部;此外，束间细胞也提前分化成纤维。最后，与对照相比，预期转基因花序茎过渡到次生生长，主要产生木质部。初级和次级维管细胞分化的刺激导致ATHB-8转基因植物的生长和发育的复杂修饰。综上所述，这些结果与ATHB-8是增殖和分化的正调节因子的假设一致，并且参与了生长素信号诱导ATHB-8的表达的正反馈回路，ATHB-8的表达反过来正调节原形成层和形成层细胞的活性以分化。
ATB-8, -9, -14, -15, and IFL1/REV are members of a small homeodomain-leucine zipper family whose genes are characterized by expression in the vascular tissue. ATHB-8, a gene positively regulated by auxin (Baima et al., 1995), is considered an early marker of the procambial cells and of the cambium during vascular regeneration after wounding. Here, we demonstrate that although the formation of the vascular system is not affected in athb8 mutants, ectopic expression of ATHB-8 in Arabidopsis plants increased the production of xylem tissue. In particular, a careful anatomical analysis of the transgenic plants indicated that the overexpression of ATHB-8 promotes Vascular cell differentiation. First, the procambial cells differentiated precociously into primary xylem. In addition, interfascicular cells also differentiated precociously into fibers. Finally, the transition to secondary growth, mainly producing xylem, was anticipated in transgenic inflorescence stems compared with controls. The stimulation of primary and secondary vascular cell differentiation resulted in complex modifications of the growth and development of the ATHB-8 transgenic plants. Taken together, these results are consistent with the hypothesis that ATHB-8 is a positive regulator of proliferation and differentiation, and participates in a positive feedback loop in which auxin signaling induces the expression of ATHB-8, which in turn positively modulates the activity of procambial and cambial cells to differentiate.