Continuous Mapping Identifies Loci Associated With Weevil Resistance [Cosmopolites sordidus (Germar)] in a Triploid Banana Population

Abstract

The first step toward marker-assisted selection is linking the phenotypes to molecular markers through quantitative trait loci (QTL) analysis. While the process is straightforward in self-pollinating diploid (2x) species, QTL analysis in polyploids requires unconventional methods. In this study, we have identified markers associated with weevil Cosmopolites sordidus (Germar) resistance in bananas using 138 triploid (2n = 3x) hybrids derived from a cross between a tetraploid “Monyet” (2n = 4x) and a 2x “Kokopo” (2n = 2x) banana genotypes. The population was genotyped by Diversity Arrays Technology Sequencing (DArTSeq), resulting in 18,009 polymorphic single nucleotide polymorphisms (SNPs) between the two parents. Marker–trait association was carried out by continuous mapping where the adjusted trait means for the corm peripheral damage (PD) and total cross-section damage (TXD), both on the logit scale, were regressed on the marker allele frequencies. Forty-four SNPs that were associated with corm PD were identified on the chromosomes 5, 6, and 8, with 41 of them located on chromosome 6 and segregated in “Kokopo.” Eleven SNPs associated with corm total TXD were identified on chromosome 6 and segregated in “Monyet.” The additive effect of replacing one reference allele with the alternative allele was determined at each marker position. The PD QTL was confirmed using conventional QTL linkage analysis in the simplex markers segregating in “Kokopo” (AAAA × RA). We also identified 43 putative genes in the vicinity of the markers significantly associated with the two traits. The identified loci associated with resistance to weevil damage will be used in the efforts of developing molecular tools for marker-assisted breeding in bananas.

Identification of the Loci Associated with Resistance to Banana Xanthomonas Wilt (Xanthomonas vasicola pv. musacearum) Using DArTSeq Markers and Continuous Mapping

“…This study used F 1 progeny from a cross between Monyet (ITC1179) and Kokopo (ITC1233) [28]. The female parent, Monyet, a tetraploid (2n = 4x = 44) genotype of the zebrina subspecies that is also resistant to weevils (Cosmopolites sordidus (Germar)) and fusarium wilt race 1 [28,29], was one of the few M. acuminata genotypes identified as mildly resistant to BXW [18].…”

“…This study used F 1 progeny from a cross between Monyet (ITC1179) and Kokopo (ITC1233) [28]. The female parent, Monyet, a tetraploid (2n = 4x = 44) genotype of the zebrina subspecies that is also resistant to weevils (Cosmopolites sordidus (Germar)) and fusarium wilt race 1 [28,29], was one of the few M. acuminata genotypes identified as mildly resistant to BXW [18]. Monyet is recorded in the Musa International Transit Center as a diploid (https://www.crop-diversity.org/mgis/accession/01BEL0841179 (accessed on 6 November 2023)), but the ploidy analysis of the Monyet plants at the International Institute of Tropical Agriculture (IITA) in Uganda found the plants to be tetraploid (4x) [28,29].…”

“…The cross did not produce any seeds because of the low pollen count of Monyet. The ploidy level of the progeny was confirmed as 3x for 94.3% of the population, with the rest being 2x (2.58%) and 4x (3.09%) [28]. This study used only the 3x progeny from the population.…”

Research Progress of Chromosome Doubling and 2n Gametes of Ornamental Plants

“…Usually, polyploids have fast growth, huge organs, high yield, higher content of active ingredients, and higher resistance to adversity. In addition, triploids usually have the advantage of being seedless or having fewer seeds, so from the last century to the present, breeders have used polyploid breeding to produce a large number of varieties [13][14][15][16][17]. Moreover, polyploid breeding is now widely used in ornamentals, such as triploid and tetraploid lilies [18,19], triploid and tetraploid tulips [15], triploid narcissus [20], triploid and tetraploid Paeonia [21], tetraploid Magnolia × soulangeana [7], etc.…”

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

“…DArTseq, a powerful genotyping-by-sequencing (GBS) approach to generate high-density linkage maps, has been successfully used for genotyping large segregating populations of diploid and triploid Musa spp. [ 54 , 55 , 56 ].…”