Gummy stem blight: One disease, three pathogens

Integrated full-length transcriptome and metabolome analysis reveals the defence response of melon to gummy stem blight

Gummy stem blight (GSB), a widespread disease causing great loss to cucurbit production, has become a major threat to melon cultivation. However, the melon-GSB interaction remains largely unknown. Here, full-length transcriptome and widely targeted metabolome were used to investigate the defence responses of resistant (PI511089) and susceptible (Payzawat) melon accessions to GSB pathogen infection at 24 h. The biosynthesis of secondary metabolites and MAPK signalling pathway were specifically enriched for differentially expressed genes in PI511890, while carbohydrate metabolism and amino acid metabolism were specifically enriched in Payzawat. More than 1000 novel genes were identified and MAPK signalling pathway was specifically enriched for them in PI511890. There were 11 793 alternative splicing events involving in the defence response to GSB. Totally, 910 metabolites were identified in Payzawat and PI511890, and flavonoids were the dominant metabolites. Integrated full-length transcriptome and metabolome analysis showed eriodictyol and oxalic acid were the potential marker metabolites for GSB resistance in melon. Moreover, posttranscription regulation was widely involved in the defence response of melon to GSB pathogen infection. These results not only improve our understanding on the interaction between melon and GSB, but also facilitate the genetic improvement of melon with GSB resistance.

Didymellaceae species associated with tea plant (Camelliasinensis) in China

Tea plant is one of the most important commercial crops worldwide. The Didymellaceae fungi can cause leaf blight disease of tea plant. In this study, 240 isolates were isolated from tea plant leaves of 10 provinces in China. Combined with multi-locus (ITS, LSU, RPB2 and TUB2) phylogenetic analysis and morphological characteristics, these isolates were identified as 25 species of six genera in Didymellaceae, including 19 known species Didymellacoffeae-arabicae, D.pomorum, D.segeticola, D.sinensis, Epicoccumcatenisporum, E.dendrobii, E.draconis, E.italicum, E.latusicollum, E.mackenziei, E.oryzae, E.poaceicola, E.rosae, E.sorghinum, E.tobaicum, Neoascochytamortariensis, Paraboeremialitseae, Remotididymellaanemophila and Stagonosporopsiscaricae, of which 15 species were new record species and six novel species, named D.yunnanensis, E.anhuiense, E.jingdongense, E.puerense, N.yunnanensis and N.zhejiangensis. Amongst all isolates, D.segeticola was the most dominant species. Pathogenicity tests on tea plant leaves showed that E.anhuiense had the strongest virulence, while E.puerense had the weakest virulence. Besides, D.pomorum, D.yunnanensis, E.dendrobii, E.italicum, E.jingdongense, E.mackenziei, E.oryzae, E.rosae, E.tobaicum, N.mortariensis, N.yunnanensis, N.zhejiangensis and R.anemophila were non-pathogenic to the tea plant.