Downregulation of HbFPS1 affects rubber biosynthesis of Hevea brasiliensis suffering from tapping panel dryness

• Published in: The Plant journal : for cell and molecular biology Vol. 113; no. 3; pp. 504 - 520
• Main Authors: Nie, Zhiyi, Kang, Guijuan, Yan, Dong, Qin, Huaide, Yang, Lifu, Zeng, Rizhong
• Format: Journal Article
• Language: English
• Published: England Blackwell Publishing Ltd 01.02.2023; John Wiley and Sons Inc
• Subjects: Bark; Biosynthesis; Chemical synthesis; Down-Regulation; farnesyl diphosphate synthase; Gene Expression Regulation, Plant - genetics; Hevea - genetics; Hevea - metabolism; Hevea brasiliensis; iTRAQ; Latex; Metabolism; Molecular weight; MYB transcription factor; Natural rubber; Original; Protein interaction; Proteins; protein–protein interaction; Proteomes; Rubber; rubber biosynthesis; Rubber trees; tapping panel dryness; transcriptome sequencing; Transcriptomes; Trees; Wounding; Hevea brasiliensis; transcriptome sequencing; rubber biosynthesis; iTRAQ; tapping panel dryness; protein-protein interaction; MYB transcription factor; farnesyl diphosphate synthase
• ISSN: 0960-7412; 1365-313X
• DOI: 10.1111/tpj.16063

SUMMARY Tapping panel dryness (TPD) is a century‐old problem that has plagued the natural rubber production of Hevea brasiliensis. TPD may result from self‐protective mechanisms of H. brasiliensis in response to stresses such as excessive hormone stimulation and mechanical wounding (bark tapping). It has been hypothesized that TPD impairs rubber biosynthesis; however, the underlying mechanisms remain poorly understood. In the present study, we firstly verified that TPD‐affected rubber trees exhibited lower rubber biosynthesis activity and greater rubber molecular weight compared to healthy rubber trees. We then demonstrated that HbFPS1, a key gene of rubber biosynthesis, and its expression products were downregulated in the latex of TPD‐affected rubber trees, as revealed by transcriptome sequencing and iTRAQ‐based proteome analysis. We further discovered that the farnesyl diphosphate synthase HbFPS1 could be recruited to small rubber particles by HbSRPP1 through protein–protein interactions to catalyze farnesyl diphosphate (FPP) synthesis and facilitate rubber biosynthesis initiation. FPP content in the latex of TPD‐affected rubber trees was significantly decreased with the downregulation of HbFPS1, ultimately resulting in abnormal development of rubber particles, decreased rubber biosynthesis activity, and increased rubber molecular weight. Upstream regulator assays indicated that a novel regulator, MYB2‐like, may be an important regulator of downregulation of HbFPS1 in the latex of TPD‐affected rubber trees. Our findings not only provide new directions for studying the molecular events involved in rubber biosynthesis and TPD syndrome and contribute to rubber management strategies, but also broaden our knowledge of plant isoprenoid metabolism and its regulatory networks. Significance Statement Our work demonstrates that HbFPS1, a key enzyme of rubber biosynthesis, could be recruited from the cytoplasm to small rubber particles by HbSRPP1 through protein–protein interactions to initiate rubber biosynthesis. FPP content in the latex of tapping panel dryness (TPD)‐affected rubber trees is significantly reduced with the downregulation of HbFPS1, ultimately resulting in abnormal development of rubber particles, decreased rubber biosynthesis activity, and increased rubber molecular weight.