Premium
KNAT 2/6b , a class I KNOX gene, impedes xylem differentiation by regulating NAC domain transcription factors in poplar
Author(s) -
Zhao Yanqiu,
Song Xueqin,
Zhou Houjun,
Wei Kaili,
Jiang Cheng,
Wang Jinnan,
Cao Yuan,
Tang Fang,
Zhao Shutang,
Lu MengZhu
Publication year - 2020
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/nph.16036
Subject(s) - xylem , microbiology and biotechnology , psychological repression , downregulation and upregulation , phloem , arabidopsis , meristem , secondary cell wall , transcription factor , cellular differentiation , vascular tissue , botany , biology , chemistry , gene expression , gene , biochemistry , mutant
Summary Wood formation is the terminal differentiation of xylem mother cells derived from cambial initials, and negative regulators play important roles in xylem differentiation. The molecular mechanism of the negative regulator of xylem differentiation Pag KNAT 2/6b was investigated. Pag KNAT 2/6b is an ortholog of Arabidopsis KNAT 2 and KNAT 6 that is highly expressed in phloem and xylem. Compared to nontransgenic control plants, transgenic poplar plants overexpressing Pag KNAT 2/6b present with altered vascular patterns, characterized by decreased secondary xylem with thin cell walls containing less cellulose, xylose and lignin. RNA sequencing analyses revealed that differentially expressed genes are enriched in xylem differentiation and secondary wall synthesis functions. Expression of NAM / ATAF / CUC ( NAC ) domain genes including Pag SND 1‐A1 , Pag SND 1‐A2 , Pag SND 1‐B2 and Pag VND 6‐C1 is downregulated by Pag KNAT 2/6b , while Pag XND 1a is directly upregulated. Accordingly, the dominant repression form of Pag KNAT 2/6b leads to increased xylem width per stem diameter through downregulation of Pag XND 1a . Pag KNAT 2/6b can inhibit cell differentiation and secondary wall deposition during wood formation in poplar by modulating the expression of NAC domain transcription factors. Direct activation of Pag XND 1a by Pag KNAT 2/6b is a key node in the negative regulatory network of xylem differentiation by KNOX s.