Details

Autor(en) / Beteiligte

• Lin, Ji‐Shan
• Huang, Xu‐Xu
• Li, Qin
• Cao, Yingping
• Bao, Yan
• Meng, Xia‐Fei
• Li, Yan‐Jie
• Fu, Chunxiang
• Hou, Bing‐Kai

Titel

UDP‐glycosyltransferase 72B1 catalyzes the glucose conjugation of monolignols and is essential for the normal cell wall lignification in Arabidopsis thaliana

Ist Teil von

• The Plant journal : for cell and molecular biology, 2016-10, Vol.88 (1), p.26-42

Ort / Verlag

England: Blackwell Publishing Ltd

Erscheinungsjahr

2016

Quelle

Wiley Online Library Journals Frontfile Complete

Beschreibungen/Notizen

• Summary Glycosylation of monolignols has been found to be widespread in land plants since the 1970s. However, whether monolignol glycosylation is crucial for cell wall lignification and how it exerts effects are still unknown. Here, we report the identification of a mutant ugt72b1 showing aggravated and ectopic lignification in floral stems along with arrested growth and anthocyanin accumulation. Histochemical assays and thioacidolysis analysis confirmed the enhanced lignification and increased lignin biosynthesis in the ugt72b1 mutant. The loss of UDP‐glycosyltransferase UGT72B1 function was responsible for the lignification phenotype, as demonstrated by complementation experiments. Enzyme activity analysis indicated that UGT72B1 could catalyze the glucose conjugation of monolignols, especially coniferyl alcohol and coniferyl aldehyde, which was confirmed by analyzing monolignol glucosides of UGT72B1 transgenic plants. Furthermore, the UGT72B1 gene was strongly expressed in young stem tissues, especially xylem tissues. However, UGT72B1 paralogs, such as UGT72B2 and UGT72B3, had weak enzyme activity toward monolignols and weak expression in stem tissues. Transcriptomic profiling showed that UGT72B1 knockout resulted in extensively increased transcript levels of genes involved in monolignol biosynthesis, lignin polymerization and cell wall‐related transcription factors, which was confirmed by quantitative real‐time PCR assays. These results provided evidence that monolignol glucosylation catalyzed by UGT72B1 was essential for normal cell wall lignification, thus offering insight into the molecular mechanism of cell wall development and cell wall lignification. Significance Statement Lignin provides mechanical support to plant stems and helps protect plants from pathogen attack. Although monolignol glucosides were reported in planta in the 1970s, whether they were important for cell wall lignification was unknown. Here we characterize a mutant in a UDP‐glycosyl transferase and show that monolignol glucosylation indeed plays an essential role in normal cell wall lignification.