The island cotton NBS-LRR gene GbaNA1 confers resistance to the non-race 1 Verticillium dahliae isolate Vd991

Summary Wilt caused by Verticillium dahliae significantly reduces cotton yields, as host resistance in commercially cultivated Gossypium species is lacking. Understanding the molecular bases of disease resistance in non-commercial Gossypium species could galvanize the development of Verticillium wilt resistance in the cultivated species. Nucleotide binding site-leucine-rich repeat (NBS-LRR) proteins play a central role in plant defense against pathogens. In this study, we focused on the relationship between a locus enriched with eight NBS-LRR genes and Verticillium wilt resistance in G. barbadense. Independent virus-induced gene silencing of each of eight NBS-LRR genes in G. barbadense cultivar Hai 7124 revealed that silencing GbaNA1 alone compromised the resistance of G. barbadense to V. dahliae isolate Vd991. In cultivar Hai 7124, GbaNA1 could be induced by V. dahliae isolate Vd991 and by ethylene, jasmonic acid, and salicylic acid. Nuclear protein localization of GbaNA1 was demonstrated by transient expression. Sequencing the GbaNA1 ortholog in nine G. hirsutum accessions revealed that all carried a non-functional allele, due to a premature peptide truncation. In addition, all ten G. barbadense and nine G. hirsutum tested carried a full length (∼1140 amino acid) homolog of the V. dahliae race 1 resistance gene Gbve1, though some sequence polymorphisms were observed. V. dahliae Vd991 is a non-race 1 isolate that lacks the Ave1 gene. Thus, the resistance imparted by GbaNA1 appears to be mediated by a mechanism distinct from recognition of the fungal effector Ave1. This article is protected by copyright. All rights reserved.