title: Overexpression of antimicrobial lytic peptides protects grapevine from Pierce's disease under greenhouse but not field conditions.
abstract: Pierce's disease (PD) caused by Xylella fastidiosa prevents cultivation of grapevine (Vitis vinifera) and susceptible hybrids in the southeastern United States and poses a major threat to the grape industry of California and Texas. Genetic resistance is the only proven control of X. fastidiosa. Genetic engineering offers an alternative to heretofore ineffective conventional breeding in order to transfer only PD resistance traits into elite cultivars. A synthetic gene encoding lytic peptide LIMA-A was introduced into V. vinifera and a Vitis hybrid to assess in planta inhibition of X. fastidiosa. Over 1050 independent transgenic plant lines were evaluated in the greenhouse, among which nine lines were selected and tested under naturally-inoculated field conditions. These selected plant lines in the greenhouse remain disease-free for 10 years, to date, even with multiple manual pathogen inoculations. However, all these lines in the field, including a grafted transgenic rootstock, succumbed to PD within 7 years. We conclude that in planta production of antimicrobial lytic peptides does not provide durable PD resistance to grapevine under field conditions.
authors.affiliation: Grape Biotechnology Core Laboratory, Mid-Florida Research and Education Center, IFAS/University of Florida, 2725 Binion Road, Apopka, FL, 32703-8504, USA.
authors.forename: Zhijian T
authors.initials: ZT
authors.lastname: Li
authors.affiliation: Grape Biotechnology Core Laboratory, Mid-Florida Research and Education Center, IFAS/University of Florida, 2725 Binion Road, Apopka, FL, 32703-8504, USA.
authors.forename: Donald L
authors.initials: DL
authors.lastname: Hopkins
authors.affiliation: Grape Biotechnology Core Laboratory, Mid-Florida Research and Education Center, IFAS/University of Florida, 2725 Binion Road, Apopka, FL, 32703-8504, USA. djg@ufl.edu.
authors.forename: Dennis J
authors.initials: DJ
authors.lastname: Gray
mesh_terms: D000595:Amino Acid Sequence; D000890:Anti-Infective Agents / Q000378:metabolism*; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry / Q000235:genetics*; D027843:Vitis / Q000382:microbiology*; D052584:Xylem / Q000382:microbiology
chemical_list: D000890:Anti-Infective Agents; D010455:Peptides
keywords: Antimicrobial activity; Durable disease resistance; Hybrid lytic peptide; Pierce’s disease resistance; Transgenic grapevine; Vitis; Xylella fastidiosa