Necrotic upper tips1 mimics heat and drought stress and encodes a protoxylem-specific transcription factor in maize
Necrotic upper tips1 mimics heat and drought stress and encodes a protoxylem-specific transcription factor in maize
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DOI：
10.1073/pnas.2005014117
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发表时间：
2020-08-25
影响因子：
11.1
通讯作者：
Chuck, George
中科院分区：
文献类型：
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作者：
Dong, Zhaobin;Xu, Zhennan;Chuck, George
在开花期间保持足够的水分运输对于适当的器官生长、受精和产量至关重要。与开花同时发生的水分亏缺会导致叶片萎蔫、坏死、雄穗布朗宁和不育，这种胁迫条件被称为“雄穗爆破”。“我们发现了一种突变体，坏死的上尖1（nut1），它模仿雄穗爆破和干旱胁迫，并揭示了这些过程背后的遗传机制。nut1的表型是明显的，只有在花的过渡，和突变体有困难移动水所示的染料吸收和运动测定。这些缺陷与原生木质部导管厚度减少相关，从而间接影响突变体中后生木质部细胞壁的完整性和功能。nut1是由Ac转座子插入到拟南芥VND Glade内的独特NAC转录因子的编码区中引起的。NUT1定位于根、茎和叶鞘的原生木质部，但不定位于后生木质部，其表达受开花诱导。NUT1下游靶基因在细胞壁生物合成、细胞凋亡以及木质部细胞壁厚度和强度的维持中起作用。这些结果表明，维持原生木质部导管的完整性，在高水分运动期间需要表达专门的，动态调节的转录因子内的脉管系统。
Maintaining sufficient water transport during flowering is essential for proper organ growth, fertilization, and yield. Water deficits that coincide with flowering result in leaf wilting, necrosis, tassel browning, and sterility, a stress condition known as "tassel blasting." We identified a mutant, necrotic upper tips1 (nut1), that mimics tassel blasting and drought stress and reveals the genetic mechanisms underlying these processes. The nut1 phenotype is evident only after the floral transition, and the mutants have difficulty moving water as shown by dye uptake and movement assays. These defects are correlated with reduced protoxylem vessel thickness that indirectly affects metaxylem cell wall integrity and function in the mutant. nut1 is caused by an Ac transposon insertion into the coding region of a unique NAC transcription factor within the VND Glade of Arabidopsis. NUT1 localizes to the developing protoxylem of root, stem, and leaf sheath, but not metaxylem, and its expression is induced by flowering. NUT1 downstream target genes function in cell wall biosynthesis, apoptosis, and maintenance of xylem cell wall thickness and strength. These results show that maintaining protoxylem vessel integrity during periods of high water movement requires the expression of specialized, dynamically regulated transcription factors within the vasculature.