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”… Show more
“…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].…”
Section: Plant Materialsmentioning
confidence: 99%
“…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].…”
Section: Plant Materialsmentioning
confidence: 99%
“…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.…”
Banana Xanthomonas wilt, caused by Xanthomonas vasicola pv. musacearum (Xvm), is a devastating disease that results in total yield loss of affected plants. Resistance to the disease is limited in Musa acuminata, but it has been identified so far in the zebrina subspecies. This study identified markers associated with tolerance to Xvm in Monyet, a tetraploid banana from the zebrina subspecies which was identified to be partially resistant to the bacterium. We used a triploid progeny of 135 F1 hybrids resulting from a cross between Monyet (Xvm partially resistant) and Kokopo (diploid and Xvm susceptible). The F1 hybrids were screened in pots for resistance to Xvm. The population was genotyped using the genotyping-by-sequencing platform of Diversity Array Technology (DArTSeq). The adjusted means of the phenotypic data were combined with the allele frequencies of the genotypic data in continuous mapping. We identified 25 SNPs associated with resistance to Xvm, and these were grouped into five quantitative traits loci (QTL) on chromosomes 2, 3, 6, and 7. For each marker, we identified the favorable allele and the additive effect of replacing the reference allele with the alternative allele. The comparison between weevil borer (Cosmopolites sordidus (Germar)) and Xvm QTL revealed one QTL shared between the two biotic stresses at the distal end of chromosome 6 but with a repulsion linkage. This linkage should be broken down by generating more recombinants in the region. We also identified 18 putative alleles in the vicinity of the SNPs associated with resistance to Xvm. Among the 18 putative genes, two particularly putative genes, namely, Ma06_g13550 and Ma06_g36840, are most likely linked to disease resistance. This study is a basis for marker-assisted selection to improve banana resistance to banana Xanthomonas wilt, especially in East and Central Africa where the disease is still devastating the crop.
“…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].…”
Section: Plant Materialsmentioning
confidence: 99%
“…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].…”
Section: Plant Materialsmentioning
confidence: 99%
“…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.…”
Banana Xanthomonas wilt, caused by Xanthomonas vasicola pv. musacearum (Xvm), is a devastating disease that results in total yield loss of affected plants. Resistance to the disease is limited in Musa acuminata, but it has been identified so far in the zebrina subspecies. This study identified markers associated with tolerance to Xvm in Monyet, a tetraploid banana from the zebrina subspecies which was identified to be partially resistant to the bacterium. We used a triploid progeny of 135 F1 hybrids resulting from a cross between Monyet (Xvm partially resistant) and Kokopo (diploid and Xvm susceptible). The F1 hybrids were screened in pots for resistance to Xvm. The population was genotyped using the genotyping-by-sequencing platform of Diversity Array Technology (DArTSeq). The adjusted means of the phenotypic data were combined with the allele frequencies of the genotypic data in continuous mapping. We identified 25 SNPs associated with resistance to Xvm, and these were grouped into five quantitative traits loci (QTL) on chromosomes 2, 3, 6, and 7. For each marker, we identified the favorable allele and the additive effect of replacing the reference allele with the alternative allele. The comparison between weevil borer (Cosmopolites sordidus (Germar)) and Xvm QTL revealed one QTL shared between the two biotic stresses at the distal end of chromosome 6 but with a repulsion linkage. This linkage should be broken down by generating more recombinants in the region. We also identified 18 putative alleles in the vicinity of the SNPs associated with resistance to Xvm. Among the 18 putative genes, two particularly putative genes, namely, Ma06_g13550 and Ma06_g36840, are most likely linked to disease resistance. This study is a basis for marker-assisted selection to improve banana resistance to banana Xanthomonas wilt, especially in East and Central Africa where the disease is still devastating the crop.
“…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.…”
Polyploid plants, an important source for the selection of ornamental plants for their advantages of faster growth, higher yields, and stronger adaptability to an adverse environment, play an essential role in the development of economic plants for agricultural stress. The methodology has been improved to decrease blindness and increase the efficiency of ornamental plants’ polyploid breeding in the long term. The progress of research on ornamental plants related to natural polyploidy, chromosome doubling, the 2n gametes pathway, and plant ploidy identification are reviewed in this paper. The main routes in polyploid breeding are chromosome doubling and sexual hybridization. Screening of suitable induction methods and plant material should be enhanced in chromosome doubling to improve induction efficiency. Regarding polyploid breeding, the utilization and research on 2n gametes produced by natural conditions or artificial induction should be strengthened to shorten the breeding years. Therefore, further research should strengthen the combination of chromosome doubling and sexual hybridization to improve breeding efficiency and strengthen the research and application of polyploid plants. This thesis review provides some reference value for polyploid breeding in ornamental plants.
“…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 ].…”
Fusarium wilt of banana is a devastating disease that has decimated banana production worldwide. Host resistance to Fusarium oxysporum f. sp. Cubense (Foc), the causal agent of this disease, is genetically dissected in this study using two Musa acuminata ssp. Malaccensis segregating populations, segregating for Foc Tropical (TR4) and Subtropical (STR4) race 4 resistance. Marker loci and trait association using 11 SNP-based PCR markers allowed the candidate region to be delimited to a 12.9 cM genetic interval corresponding to a 959 kb region on chromosome 3 of ‘DH-Pahang’ reference assembly v4. Within this region, there was a cluster of pattern recognition receptors, namely leucine-rich repeat ectodomain containing receptor-like protein kinases, cysteine-rich cell-wall-associated protein kinases, and leaf rust 10 disease-resistance locus receptor-like proteins, positioned in an interspersed arrangement. Their transcript levels were rapidly upregulated in the resistant progenies but not in the susceptible F2 progenies at the onset of infection. This suggests that one or several of these genes may control resistance at this locus. To confirm the segregation of single-gene resistance, we generated an inter-cross between the resistant parent ‘Ma850’ and a susceptible line ‘Ma848’, to show that the STR4 resistance co-segregated with marker ‘28820’ at this locus. Finally, an informative SNP marker 29730 allowed the locus-specific resistance to be assessed in a collection of diploid and polyploid banana plants. Of the 60 lines screened, 22 lines were predicted to carry resistance at this locus, including lines known to be TR4-resistant, such as ‘Pahang’, ‘SH-3362’, ‘SH-3217’, ‘Ma-ITC0250’, and ‘DH-Pahang/CIRAD 930’. Additional screening in the International Institute for Tropical Agriculture’s collection suggests that the dominant allele is common among the elite ‘Matooke’ NARITA hybrids, as well as in other triploid or tetraploid hybrids derived from East African highland bananas. Fine mapping and candidate gene identification will allow characterization of molecular mechanisms underlying the TR4 resistance. The markers developed in this study can now aid the marker-assisted selection of TR4 resistance in breeding programs around the world.
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