AUTHOR=Bracuto Valentina , Appiano Michela , Zheng Zheng , Wolters Anne-Marie A. , Yan Zhe , Ricciardi Luigi , Visser Richard G. F. , Pavan Stefano , Bai Yuling 

TITLE=Functional Characterization of a Syntaxin Involved in Tomato (Solanum lycopersicum) Resistance against Powdery Mildew

JOURNAL=Frontiers in Plant Science

VOLUME=8

YEAR=2017

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2017.01573

DOI=10.3389/fpls.2017.01573

ISSN=1664-462X

ABSTRACT=<p>Specific syntaxins, such as Arabidopsis AtPEN1 and its barley ortholog ROR2, play a major role in plant defense against powdery mildews. Indeed, the impairment of these genes results in increased fungal penetration in both host and non-host interactions. In this study, a genome-wide survey allowed the identification of 21 tomato syntaxins. Two of them, named <italic>SlPEN1a</italic> and <italic>SlPEN1b</italic>, are closely related to <italic>AtPEN1</italic>. RNAi-based silencing of <italic>SlPEN1a</italic> in a tomato line carrying a loss-of-function mutation of the susceptibility gene <italic>SlMLO1</italic> led to compromised resistance toward the tomato powdery mildew fungus <italic>Oidium neolycopersici</italic>. Moreover, it resulted in a significant increase in the penetration rate of the non-adapted powdery mildew fungus <italic>Blumeria graminis</italic> f. sp. <italic>hordei</italic>. Codon-based evolutionary analysis and multiple alignments allowed the detection of amino acid residues that are under purifying selection and are specifically conserved in syntaxins involved in plant-powdery mildew interactions. Our findings provide both insights on the evolution of syntaxins and information about their function which is of interest for future studies on plant–pathogen interactions and tomato breeding.</p>