Function of Hevea brasiliensis NAC1 in dehydration-induced laticifer differentiation and latex biosynthesis
HbNAC1 is a transcription factor in rubber plants whose expression is induced by dehydration, leading to latex biosynthesis.
Laticifer is a special tissue in Hevea brasiliensis where natural rubber is biosynthesized and accumulated. In young stems of epicormic shoots, the differentiation of secondary laticifers can be induced by wounding, which can be prevented when the wounding site is wrapped. Using this system, differentially expressed genes were screened by suppression subtractive hybridization (SSH) and macroarray analyses. This led to the identification of several dehydration-related genes that could be involved in laticifer differentiation and/or latex biosynthesis, including a NAC transcription factor (termed as HbNAC1). Tissue sections confirmed that local tissue dehydration was a key signal for laticifer differentiation. HbNAC1 was localized at the nucleus and showed strong transcriptional activity in yeast, suggesting that HbNAC1 is a transcription factor. Furthermore, HbNAC1 was found to bind to the cis-element CACG in the promoter region of the gene encoding the small rubber particle protein (SRPP). Transgenic experiments also confirmed that HbNAC1 interacted with the SRPP promoter when co-expressed, and enhanced expression of the reporter gene β-glucuronidase occurred in planta. In addition, overexpression of HbNAC1 in tobacco plants conferred drought tolerance. Together, the data suggest that HbNAC1 might be involved in dehydration-induced laticifer differentiation and latex biosynthesis.
KeywordsHevea brasiliensis Dehydration Laticifer differentiation HbNAC1 HbSRPP
Green fluorescent protein
Late embryogenesis abundant-like proteins
NAC recognition sequence
Small rubber particle protein
Suppression subtractive hybridization
Vegetative storage protein
This work was supported by the National Natural Science Foundation of China [Grant nos. 31370608, 31260170, 31060107] and the Hainan Major Research Project for Science and Technology [Grant no. ZDZX2013023]. We would like to thank Professor Shiqing Peng for kindly providing the bait vectors for rubber biosynthesis related genes.
Compliance with ethical standards
Conflict of interest
All authors declare they have no actual or potential competing financial interest.
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