Zhong Ruiqin, Ye Zheng-Hua
a Department of Plant Biology ; University of Georgia ; Athens , GA USA.
Plant Signal Behav. 2015;10(2):e989746. doi: 10.4161/15592324.2014.989746.
Transcriptional regulation of secondary wall biosynthesis in Arabidopsis thaliana has been shown to be mediated by a group of secondary wall NAC master switches, including NST1, NST2, SND1 and VND1 to VND7. It has been shown that VND1 to VND7 regulate secondary wall biosynthesis in vessels, NST1 and NST2 function redundantly in anther endothecium, and SND1 and NST1 are required for secondary wall thickening in fibers of stems. However, it is unknown whether NST2 is involved in regulating secondary wall biosynthesis in fibers of stems. In this report, we demonstrated that similar to SND1, NST2 together with NST1 were highly expressed in interfascicular fibers and xylary fibers but not in vessels of stems. Although simultaneous mutations of SND1 and NST1 have been shown to result in a significant impairment of secondary wall thickening in fibers, a small amount of secondary walls was deposited in fibers during the late stage of stem development. In contrast, simultaneous mutations of SND1, NST1 and NST2 led to a complete loss of secondary wall thickening in fibers. These results demonstrate that NST2 together with SND1 and NST1 regulate secondary wall biosynthesis in fibers of stems.
拟南芥次生壁生物合成的转录调控已被证明由一组次生壁NAC主开关介导，包括NST1、NST2、SND1以及VND1至VND7。研究表明，VND1至VND7调控导管中的次生壁生物合成，NST1和NST2在花药内皮中功能冗余，而SND1和NST1是茎纤维中次生壁加厚所必需的。然而，NST2是否参与调控茎纤维中的次生壁生物合成尚不清楚。在本报告中，我们证明，与SND1相似，NST2与NST1在束间纤维和木质部纤维中高表达，但在茎的导管中不表达。尽管已表明SND1和NST1同时突变会导致纤维中次生壁加厚显著受损，但在茎发育后期，仍有少量次生壁沉积在纤维中。相比之下，SND1、NST1和NST2同时突变导致纤维中次生壁加厚完全丧失。这些结果表明，NST2与SND1和NST1一起调控茎纤维中的次生壁生物合成。
