AUTHOR=Guo Wei-Li , Chen Bi-Hua , Guo Yan-Yan , Chen Xue-Jin , Li Qing-Fei , Yang He-Lian , Li Xin-Zheng , Zhou Jun-Guo , Wang Guang-Yin 

TITLE=Expression of Pumpkin CmbHLH87 Gene Improves Powdery Mildew Resistance in Tobacco

JOURNAL=Frontiers in Plant Science

VOLUME=11

YEAR=2020

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2020.00163

DOI=10.3389/fpls.2020.00163

ISSN=1664-462X

ABSTRACT=<p>Powdery mildew (PM), caused by <italic>Podosphaera xanthii</italic>, is a major threat to the global cucurbit yield. The molecular mechanisms underlying the PM resistance of pumpkin (<italic>Cucurbita moschata</italic> Duch.) are largely unknown. A homolog of the basic helix-loop-helix (bHLH) transcription factor was previously identified through a transcriptomic analysis of a PM-resistant pumpkin. In this study, this bHLH homolog in pumpkin has been functionally characterized. CmbHLH87 is present in the nucleus. <italic>CmbHLH87</italic> expression in the PM-resistant material was considerably downregulated by PM; and abscisic acid, methyl jasmonate, ethephon, and NaCl treatments induced <italic>CmbHLH87</italic> expression. Ectopic expression of <italic>CmbHLH87</italic> in tobacco plants alleviated the PM symptoms on the leaves, accelerated cell necrosis, and enhanced H<sub>2</sub>O<sub>2</sub> accumulation. The expression levels of <italic>PR1a</italic>, <italic>PR5</italic>, and <italic>NPR1</italic> were higher in the PM-infected transgenic plants than in PM-infected wild-type plants. Additionally, the chlorosis and yellowing of plant materials were less extensive and the concentration of bacteria at infection sites was lower in the transgenic tobacco plants than in the wild-type plants in response to bacterial wilt and scab pathogens. <italic>CmbHLH87</italic> may be useful for genetic engineering of novel pumpkin cultivars in the future.</p>