Identification of FaNBS-encoding genes responsive to Colletotrichum fructicola infection in strawberry (Fragaria ×ananassa Duchase)

Abstract

Anthracnose caused by C. fructicola is a serious fungal disease in strawberry (Fragaria ×ananassa), but the molecular mechanism is still unclear. Here, approximately 232 FaNBS-encoding genes were identified by RNA-seq, of which 53 were specifically annotated in the Fragaria ×ananassa genome. After C. fructicola inoculation, a total of 12, 9 and 24 differentially expressed FaNBS-encoding genes were observed at 24, 72, and 96 Hpi in the Fragaria ×ananassa (cv. Jiuxiang). Furthermore, we manually annotated 40 FaNBS-encoding genes fused with other integrated domains, 27 of which are FaNBS-RPW8 fusions. Most of the RPW8 domains from the FaNBS-RPW8 fusions were conserved in the tyrosine (Y) and glycine (G) residues. Interestingly, the heatmap, Venn diagram and qRT-PCR analysis showed that the expression of an FaNBS-RPW8 fusion (mrna24117.1-v1.0-hybrid) was markedly induced at different stages after C. fructicola inoculation in the susceptible cultivar of Jiuxiang. Altogether, the results of the present study provide information from comprehensive structure and expression analyses of FaNBS-encoding genes and add insight into the molecular mechanism underlying FaNBS-RPW8-mediated resistance to C. fructicola in strawberry (Fragaria ×ananassa).