Genome-wide identification of NDR1/HIN1-like genes in kiwifruit and function analysis of AeNHL17 in response to disease resistance.

BACKGROUND: NDR1/HIN1-like (NHL) genes play crucial roles in Psa resistance. Kiwifruit canker, caused by Pseudomonas syringae pv. Actinidiae (Psa) infection is one of the most serious diseases affecting the kiwifruit industry. However, the key NHL has not yet been identified in kiwifruit. RESULTS: In this study, we conducted a genome-wide identification of NHL family in kiwifruit (Actinidia eriantha). A total of 33 AeNHLs were divided into five domain-conserved subfamilies, which were mainly assigned into phytohormones and defense responses. The expression of AeNHL genes was analyzed to identify key genes in response to Psa, and we found AeNHL17 was highly expressed upon Psa inoculation. Transgenic tobacco overexpressing AeNHL17 presented higher resistance to Psa than wild-type (WT) tobacco, implying a key role for AeNHL17 in Psa resistance. Finally, we carried out a stable genetic transformation of kiwifruit (A. chinensis), which is sensitive to Psa, and found that the overexpression of AeNHL17 increased resistance to infection. AeNHL17-silenced plants exhibited larger disease lesions than control plants. CONCLUSIONS: Our findings revealed the function of AaNHL17 in Psa resistance, providing new data regarding the functional analysis of the NHL gene family in kiwifruit.