Zhang Bo, Sztojka Bernadette, Seyfferth Carolin, Escamez Sacha, Miskolczi Pál, Chantreau Maxime, Bakó László, Delhomme Nicolas, Gorzsás András, Bhalerao Rishikesh P, Tuominen Hannele
Umeå Plant Science Centre, Department of Plant Physiology, Umeå University, Umeå, Sweden.
Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, Umeå, Sweden.
J Exp Bot. 2020 Sep 19;71(18):5484-5494. doi: 10.1093/jxb/eraa264.
PIRIN2 (PRN2) was earlier reported to suppress syringyl (S)-type lignin accumulation of xylem vessels of Arabidopsis thaliana. In the present study, we report yeast two-hybrid results supporting the interaction of PRN2 with HISTONE MONOUBIQUITINATION2 (HUB2) in Arabidopsis. HUB2 has been previously implicated in several plant developmental processes, but not in lignification. Interaction between PRN2 and HUB2 was verified by β-galactosidase enzymatic and co-immunoprecipitation assays. HUB2 promoted the deposition of S-type lignin in the secondary cell walls of both stem and hypocotyl tissues, as analysed by pyrolysis-GC/MS. Chemical fingerprinting of individual xylem vessel cell walls by Raman and Fourier transform infrared microspectroscopy supported the function of HUB2 in lignin deposition. These results, together with a genetic analysis of the hub2 prn2 double mutant, support the antagonistic function of PRN2 and HUB2 in deposition of S-type lignin. Transcriptome analyses indicated the opposite regulation of the S-type lignin biosynthetic gene FERULATE-5-HYDROXYLASE1 by PRN2 and HUB2 as the underlying mechanism. PRN2 and HUB2 promoter activities co-localized in cells neighbouring the xylem vessel elements, suggesting that the S-type lignin-promoting function of HUB2 is antagonized by PRN2 for the benefit of the guaiacyl (G)-type lignin enrichment of the neighbouring xylem vessel elements.
先前有报道称，拟南芥木质部导管中的紫丁香基（S）型木质素积累受PIRIN2（PRN2）抑制。在本研究中，我们报告了酵母双杂交结果，支持PRN2与拟南芥中的组蛋白单泛素化2（HUB2）相互作用。HUB2先前已涉及多种植物发育过程，但未涉及木质化过程。通过β-半乳糖苷酶酶促分析和免疫共沉淀分析验证了PRN2与HUB2之间的相互作用。通过热解-气相色谱/质谱分析，HUB2促进了茎和下胚轴组织次生细胞壁中S型木质素的沉积。通过拉曼光谱和傅里叶变换红外显微光谱对单个木质部导管细胞壁进行化学指纹图谱分析，支持了HUB2在木质素沉积中的功能。这些结果，连同对hub2 prn2双突变体的遗传分析，支持了PRN2和HUB2在S型木质素沉积中的拮抗功能。转录组分析表明，PRN2和HUB2对S型木质素生物合成基因阿魏酸-5-羟化酶1的调控相反，这是其潜在机制。PRN2和HUB2的启动子活性共定位于与木质部导管分子相邻的细胞中，这表明HUB2促进S型木质素的功能被PRN2拮抗，从而有利于相邻木质部导管分子中愈创木基（G）型木质素的富集。
