Zhou Yangyan, Zhang Yue, Wang Xuewen, Han Xiao, An Yi, Lin Shiwei, Shen Chao, Wen JiaLong, Liu Chao, Yin Weilun, Xia Xinli
Beijing Advanced Innovation Center for Tree Breeding by Molecular Design, National Engineering Laboratory for Tree Breeding, College of Biological Sciences and Technology, Beijing Forestry University, Beijing, 100083, China.
Department of Genetics, University of Georgia, Athens, GA, 30602, USA.
New Phytol. 2020 Jul;227(2):407-426. doi: 10.1111/nph.16524. Epub 2020 Apr 2.
Root growth control plays an important role in plant adaptation to drought stress, but the underlying molecular mechanisms of this control remain largely elusive. Here, a root-specific nuclear factor Y (NF-Y) transcription factor PdNF-YB21 was isolated from Populus. The functional mechanism of PdNF-YB21 was characterised by various morphological, physiological, molecular, biochemical and spectroscopy techniques. Overexpression of PdNF-YB21 in poplar promoted root growth with highly lignified and enlarged xylem vessels, resulting in increased drought resistance. By contrast, CRISPR/Cas9-mediated poplar mutant nf-yb21 exhibited reduced root growth and drought resistance. PdNF-YB21 interacted with PdFUSCA3 (PdFUS3), a B3 domain transcription factor. PdFUS3 directly activated the promoter of the abscisic acid (ABA) synthesis key gene PdNCED3, resulting in a significant increase in root ABA content in poplars subjected to water deficit. Coexpression of poplar NF-YB21 and FUS3 significantly enhanced the expression of PdNCED3. Furthermore, ABA promoted indoylacetic acid transport in root tips, which ultimately increased root growth and drought resistance. Taken together, our data indicate that NF-YB21-FUS3-NCED3 functions as an important avenue in auxin-regulated poplar root growth in response to drought.
根系生长控制在植物适应干旱胁迫中起着重要作用，但其控制的潜在分子机制仍 largely 难以捉摸。在这里，从杨树中分离出一种根特异性核因子 Y（NF-Y）转录因子 PdNF-YB21。通过各种形态学、生理学、分子学、生物化学和光谱学技术对 PdNF-YB21 的功能机制进行了表征。在杨树中过表达 PdNF-YB21 促进了根系生长，木质部导管高度木质化且增大，从而提高了抗旱性。相比之下，CRISPR/Cas9 介导的杨树突变体 nf-yb21 根系生长和抗旱性降低。PdNF-YB21 与 B3 结构域转录因子 PdFUSCA3（PdFUS3）相互作用。PdFUS3 直接激活脱落酸（ABA）合成关键基因 PdNCED3 的启动子，导致缺水杨树根系 ABA 含量显著增加。杨树 NF-YB21 和 FUS3 的共表达显著增强了 PdNCED3 的表达。此外，ABA 促进了根尖中吲哚乙酸的运输，最终增加了根系生长和抗旱性。综上所述，我们的数据表明 NF-YB21-FUS3-NCED3 作为生长素调节杨树根系生长以响应干旱的重要途径发挥作用。
