AUTHOR=Shen Xuexue , Yan Zhe , Wang Xiaoxuan , Wang Yinlei , Arens Marjon , Du Yongchen , Visser Richard G. F. , Kormelink Richard , Bai Yuling , Wolters Anne-Marie A. 

TITLE=The NLR Protein Encoded by the Resistance Gene Ty-2 Is Triggered by the Replication-Associated Protein Rep/C1 of Tomato Yellow Leaf Curl Virus

JOURNAL=Frontiers in Plant Science

VOLUME=11

YEAR=2020

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2020.545306

DOI=10.3389/fpls.2020.545306

ISSN=1664-462X

ABSTRACT=<p>The whitefly-transmitted tomato yellow leaf curl virus (TYLCV) is one of the most destructive viral pathogens of cultivated tomato. To combat TYLCV, resistance gene <italic>Ty-2</italic> has been introduced into cultivated tomato (<italic>Solanum lycopersicum</italic>) from wild tomato species <italic>Solanum habrochaites</italic> by interspecific crossing. Introgression lines with <italic>Ty-2</italic> contain a large inversion compared with <italic>S. lycopersicum</italic>, which causes severe suppression of recombination and has hampered the cloning of <italic>Ty-2</italic> so far. Here, we report the fine-mapping and cloning of <italic>Ty-2</italic> using crosses between a <italic>Ty-2</italic> introgression line and several susceptible <italic>S. habrochaites</italic> accessions. <italic>Ty-2</italic> was shown to encode a nucleotide-binding leucine-rich repeat (NLR) protein. For breeding purposes, a highly specific DNA marker tightly linked to the <italic>Ty-2</italic> gene was developed permitting marker-assisted selection. The resistance mediated by <italic>Ty-2</italic> was effective against the Israel strain of TYLCV (TYLCV-IL) and tomato yellow leaf curl virus-[China : Shanghai2] (TYLCV-[CN : SH2]), but not against tomato yellow leaf curl Sardinia virus (TYLCSV) and leafhopper-transmitted beet curly top virus (BCTV). By co-infiltration experiments we showed that transient expression of the Rep/C1 protein of TYLCV, but not of TYLCSV triggered a hypersensitive response (HR) in <italic>Nicotiana benthamiana</italic> plants co-expressing the <italic>Ty-2</italic> gene. Our results indicate that the <italic>Rep</italic>/<italic>C1</italic> gene of TYLCV-IL presents the avirulence determinant of <italic>Ty-2-</italic>mediated resistance.</p>