GbHyPRP1, encoding a hybrid proline-rich protein, is involved in resistance to Verticillium dahliae in cotton

Functional Genomics

oral

Yang, Jun; Wang, Xingfen; Zhang, Yan; Wang, Weiqiao; Wu, Jinhua; Ma, Zhiying

Yang, Jun

Ma, Zhiying

Verticillium wilt is the most important fungal disease that causes severe losses in yield and fiber quality of cotton in many cotton-growing areas. Developing tolerant cotton cultivars by incorporating genes from resistant germplasm is now regarded as a potential strategy for controlling this disease. Here, we identified a gene of hybrid proline-rich protein in Gossypium barbadense, designated as GbHyPRP1, which encodes a protein containing a proline-rich repetitive domain (PRD) at the N-terminus and a hydrophobic C-terminus Pollen Ole e I domain that is mostly expressed in the root and stem. When the cotton seedlings were inoculated with Verticillium dahliae, the expressional level of HyPRP1 dropped drastically within 48h of monitoring in roots, whereas in stems the transcript was kept unchanged. To better characterize the function of GbHyPRP1 in cotton resistance to V. dahliae, we employed virus-induced gene silencing (VIGS) to suppress endogenous HyPRP1 in G. barbadense. As a result, HyPRP1-silenced plants displayed more resistant to V. dahliae, with a dramatic increase in length of primary roots compared to the control. Additionally, we transformed GbHyPRP1 into V. dahliae-susceptible Arabidopsis ecotype Columbia by Agrobacterium-mediated transformation. Statistical analysis of the disease index showed that overexpression of GbHyPRP1 compromised transgenic Arabidopsis plants resistance to V. dahliae. Furthermore, a GbHyPRP1 promoter region of 1431 bp was isolated by PCR and has been validated by transgenic Arabidopsis carrying the GUS ( -glucuronidase) reporter gene fused to the 1431 bp fragment, and T2 plants were used for GUS histochemical assay. Putative cis-acting elements in the promoter were sought in PLACE database. Several distinct cis-acting regulatory DNA elements associated with the response to abiotic/biotic stresses and phytohormone were identified, such as MYB recognition site, ABRE (ABA-responsive element), ERE (ethylene-responsive element) etc. Especially, we further verified cis-acting element of ABRE through the response of GbHyPRP1 transcripts to exogenous ABA in cotton plants.The result showed that GbHyPRP1 was markedly down-regulated after 6-24 h of ABA treatment. Overall, our results suggest that GbHyPRP1 performs a role in negative regulation of the cotton resistance to V. dahlia, and has a potential value for the resistance improvement of cotton Verticillium wilt.