AUTHOR=Zhang Yi , Xu Kedong , Pei Dongli , Yu Deshui , Zhang Ju , Li Xiaoli , Chen Guo , Yang Hui , Zhou Wenjie , Li Chengwei 

TITLE=ShORR-1, a Novel Tomato Gene, Confers Enhanced Host Resistance to Oidium neolycopersici

JOURNAL=Frontiers in Plant Science

VOLUME=10

YEAR=2019

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2019.01400

DOI=10.3389/fpls.2019.01400

ISSN=1664-462X

ABSTRACT=<p>A previous complementary cDNA-amplified fragment length polymorphism (cDNA-AFLP) analysis examined responses to the powdery mildew pathogen <italic>Oidium neolycopersici</italic> (<italic>On</italic>) of the resistant cultivar <italic>Solanum habrochiates</italic> G1.1560, carrying the <italic>Ol-1</italic> resistance gene, and susceptible cultivar <italic>S. lycopersicum</italic> Moneymaker (MM). Among other findings, a differentially expressed transcript-derived fragment (DE-TDF) (M14E72-213) was upregulated in near isogenic line (NIL)-<italic>Ol-1</italic>, but absent in MM. This DE-TDF showed high homology to a gene of unknown function, which we named <italic>ShORR-1</italic> (<italic>Solanum habrochaites Oidium Resistance Required-1</italic>). However, MM homolog of <italic>ShORR-1</italic> (named <italic>ShORR-1-M</italic>) was still found with 95.26% nucleic acid sequence similarity to <italic>ShORR-1</italic> from G1.1560 (named <italic>ShORR-1-G</italic>); this was because the cut sites of restriction enzymes in the previous complementary cDNA-AFLP analysis was absent in <italic>ShORR-1-M</italic> and differs at 13 amino acids from <italic>ShORR-1-G</italic>. Transient expression in onion epidermal cells showed that ShORR-1 is a membrane-localized protein. Virus-induced gene silencing (VIGS) of <italic>ShORR-1-G</italic> in G1.1560 plants increased susceptibility to <italic>On</italic>. Furthermore, overexpressing of <italic>ShORR-1-G</italic> conferred MM with resistance to <italic>On</italic>, involving extensive hydrogen peroxide accumulation and formation of abnormal haustoria. Knockdown of <italic>ShORR-1-M</italic> in MM did not affect its susceptibility to <italic>On</italic>, while overexpressing of <italic>ShORR-1-M</italic> enhanced MM’s susceptibility to <italic>On</italic>. We also found that changes in transcript levels of six well-known hormone signaling and defense-related genes are involved in <italic>ShORR-1-G</italic>-mediated resistance to <italic>On</italic>. The results indicate that <italic>ShORR-1-M</italic> and <italic>ShORR-1-G</italic> have antagonistic effects in tomato responses to <italic>On</italic>, and that <italic>ShORR-1</italic> is essential for <italic>Ol-1</italic>-mediated resistance in tomato.</p>