Objective The development of secondary cell wall is vital for the wood formation, and revealing the molecular regulation mechanism of secondary wall formation in forest will provide a theoretical basis for improving its wood quality.
Method (1) In this study, PdKNAT7 gene was cloned from fast-growing poplar NE19, and its expression vector was constructed. Arabidopsis thaliana was transformed by inflorescence infection, and overexpression plants were screened. (2) The subcellular localization of PdKNAT7 was implemented by Agrobacterium mediated transient transformation in tobacco. (3) The secondary thickening of flower stalk base in different genotypes of Arabidopsis thaliana was observed by hand sectioning. (4) 84K poplar was transiently transformed by vacuum infiltration. (5) qRT-PCR was used to analyze the expression of PdKNAT7 gene in different poplar strains, and reveal the expression patterns of related genes involved in secondary wall formation in Arabidopsis thaliana and poplar.
Result (1) PdKNAT7 was localized in the nucleus. (2) PdKNAT7 was mainly expressed in the stem of NE19, and the expression level was higher than that of poplar 107. (3) Compared with the wild type, the interfascicular fiber wall of the flower stalk base of the overexpression plant became thinner, and the xylary fiber wall became thicker, while the mutant was just opposite to the overexpression plant; in addition, the vessel wall of mutant was thicker. (4) The expression levels of 4CL1, C4H1, CCR1, CesA8, IRX9 and IRX10 genes were down regulated in the overexpression plants, and the mutant was on the contrary. (5) The expression levels of 4CL3, C4H1, CCR1, CesA8, IRX9 and IRX10 genes in 84K poplar transiently transformed with PdKNAT7 gene were also down regulated.
Conclusion PdKNAT7 affects the thickness of secondary cell wall by regulating the accumulation of lignin and cellulose in Arabidopsis thaliana.