Identification of a Major QTL-Controlling Resistance to the Subtropical Race 4 of Fusarium oxysporum f. sp. cubense in Musa acuminata ssp. malaccensis

Abstract

Vascular wilt caused by the ascomycete fungal pathogen Fusarium oxysporum f. sp. cubense (Foc) is a major constraint of banana production around the world. The virulent race, namely Tropical Race 4, can infect all Cavendish-type banana plants and is now widespread across the globe, causing devastating losses to global banana production. In this study, we characterized Foc Subtropical Race 4 (STR4) resistance in a wild banana relative which, through estimated genome size and ancestry analysis, was confirmed to be Musa acuminata ssp. malaccensis. Using a self-derived F2 population segregating for STR4 resistance, quantitative trait loci sequencing (QTL-seq) was performed on bulks consisting of resistant and susceptible individuals. Changes in SNP index between the bulks revealed a major QTL located on the distal end of the long arm of chromosome 3. Multiple resistance genes are present in this region. Identification of chromosome regions conferring resistance to Foc can facilitate marker assisted selection in breeding programs and paves the way towards identifying genes underpinning resistance.

Telomere-to-telomere haplotype-resolved reference genome reveals subgenome divergence and disease resistance in triploid Cavendish banana

“…Some contracted gene families in the ‘Baxijiao’ genome were involved in the biological processes associated with response to external biotic and abiotic factors. Accumulating evidence indicates that banana cultivars have generally reduced resistance to pathogens and environmental stresses than their wild ancestors [ 43 , 44 ]. These contracted gene families will provide candidates for further investigations on the genetic basis of the reducing resistance in banana cultivars.…”

“…Here we found that considerably fewer resistance genes were identified in ‘Baxijiao’ than in wild banana M. acuminata . Recently, Chen et al [ 44 ] have identified a major quantitative trait loci (QTL)controlling resistance to the subtropical race 4 (STR4, affecting Cavendish bananas in the subtropics) of Foc in M. acuminata ssp. malaccensis .…”

Genetic Mapping, Candidate Gene Identification and Marker Validation for Host Plant Resistance to the Race 4 of Fusarium oxysporum f. sp. cubense using Musa acuminata ssp. malaccensis

“…Although one critical recombinant (852-7) did not produce any symptoms in the TR4 screening, the phenotypic data were generally concordant with the genetic interval defined for both STR4-and TR4resistant loci. Within this interval, there was a cluster of receptor-like kinases (LRR XII subfamily) and receptor-like proteins (LRR RLP subfamily) positioned in an interspersed arrangement [57]. They, respectively, belong to the LRR XII and LRR RLP subfamilies of pattern recognition receptors [72,77].…”

“…malaccensis parents were used in this study. The progenies of the R (resistant) parents 'Ma850', 'Ma851', and 'Ma852' segregated for Foc-STR4 and Foc-TR4 resistance [57,58], whereas the S (susceptible) parents 'Ma845', 'Ma846', and 'Ma848' were uniformly susceptible to Foc-STR4 (Figure 1A). Three close-pollinated F 2 populations, collectively called Population 1 and consisting of 435 individuals, were developed for mapping.…”

“…malaccensis lines were resistant to both STR4 and TR4 [57,58], and they were heterozygous for single-gene resistance, with resistance dominant over susceptibility. A quantitative trait-locus-bysequencing (QTL-seq) approach was used to identify a major locus on chromosome 3 conferring resistance to STR4 [57]. This QTL is distinct to the QTL identified on chromosome 10 for race 1 and TR4 resistance [54].…”