Ethylene response factors regulate expression of HbSUT3, the sucrose influx carrier in laticifers of <i>Hevea brasiliensis</i>

Abstract Natural rubber is an important industrial raw material and commercially produced by trees (Hevea brasiliensis). The sucrose transporter HbSUT3 plays essential role in production. Its expression latex (cytoplasm of rubber-producing laticifers) induced bark treatment with Ethrel, ethylene releaser, the inducing effect correlates well Ethrel-stimulated yield increase. However, mechanisms induction on are not known. Here, five Ethylene Response Factor (ERF) genes were identified from cDNA library Hevea yeast one-hybrid screening promoter gene as bait. As revealed a tobacco (Nicotiana tabacum) protoplast transient system, these HbERFs mainly localized nucleus four them exhibited apparent transactivation activity. Of HbERF genes, HbERF-IXc4 was most frequently screened one-hybrid, accounting for 65% ERF clones obtained. Moreover, among HbERFs, showed strongest capacity when expressed protoplast, highest transcript abundance close expressional correlation its target gene, HbSUT3, response to Ethrel treatment. Taken together, our results indicate that ERFs, especially HbERF-IXc4, critically involved activation after bark, thus stimulated yield.