Enhanced resistance to white rot in Ipomoea batatas expressing a Trichoderma harzianum chitinase gene

Collapsed sweet potato vines observed in Hangzhou fields in September 2019 were found to be due to Sclerotinia sclerotiorum based on its morphology and ITS rDNA sequence . Here, the chitinase gene chit42 from Trichoderma harzianum was introduced into Ipomoea batatas using Agrobacterium -mediated transformation to evaluate the effect against subsequent disease severity from S. sclerotiorum . PCR analysis detected the transgene in 23 transformants with a transformation efficiency of 5.1%. RT-PCR analysis showed transgene mRNA expression in all four selected lines harboring chit42 . Enzymatic tests showed a significant increase in the activity of endochitinase in extracts from leaf tissues of chit42 -transgenic 75-day sweet potato lines. Virulence of three genetically different isolates was markedly reduced on leaves of 75-day-old chit42- transgenic plants compared with the controls. To our knowledge, this is the first report of S. sclerotiorum on sweet potato plants in China.