RNAi of the sesquiterpene cyclase gene for phytoalexin production impairs pre‐ and post‐invasive resistance to potato blight pathogens. (16th April 2019)

• Record Type: Journal Article
• Authors: Yoshioka, Miki; Adachi, Ayako; Sato, Yutaka; Doke, Noriyuki; Kondo, Tatsuhiko; Yoshioka, Hirofumi
• Is Part Of: Molecular plant pathology. Volume 20:Number 7(2019)
• Page Start: 907
• Page End: 922
• Publication Date: 2019-04-16
• Subjects: Phytoalexin -- plant immunity -- potato blight pathogen -- RNA interference -- sesquiterpene cyclase; Plant diseases -- Molecular aspects -- Periodicals; Plant-pathogen relationships -- Molecular aspects -- Periodicals; 571.936
• DOI: 10.1111/mpp.12802
• Languages: English
• ISSNs: 1464-6722

Abstract

Summary: Potato antimicrobial sesquiterpenoid phytoalexins lubimin and rishitin have been implicated in resistance to the late blight pathogen, Phytophthora infestans and early blight pathogen, Alternaria solani . We generated transgenic potato plants in which sesquiterpene cyclase, a key enzyme for production of lubimin and rishitin, is compromised by RNAi to investigate the role of phytoalexins in potato defence. The transgenic tubers were deficient in phytoalexins and exhibited reduced post‐invasive resistance to an avirulent isolate of P. infestans, resulting in successful infection of the first attacked cells without induction of cell death. However, cell death was observed in the subsequently penetrated cells. Although we failed to detect phytoalexins and antifungal activity in the extract from wild‐type leaves, post‐invasive resistance to avirulent P. infestans was reduced in transgenic leaves. On the other hand, A. solani frequently penetrated epidermal cells of transgenic leaves and caused severe disease symptoms presumably from a deficiency in unidentified antifungal compounds. The contribution of antimicrobial components to resistance to penetration and later colonization may vary depending on the pathogen species, suggesting that sesquiterpene cyclase‐mediated compounds participate in pre‐invasive resistance to necrotrophic pathogen A. solani and post‐invasive resistance to hemibiotrophic pathogen P. infestans .