Empoasca species leafhoppers are a major insect pest of common bean (Phaseolus vulgaris L.), that cause significant economic losses in both tropical (E. kraemeri) and temperate (E. fabae) regions of the Americas. The objective of this study was to use Insertion–Deletion (InDel) and single‐nucleotide polymorphism (SNP) markers from the BARCBean6K_3 Beadchip to identify quantitative trait loci (QTL) associated with traits related to leafhopper resistance in common bean. Traits for leaf curl and leaf burn damage, as well as Empoasca spp. nymph counts, were evaluated in an inbred backcross line population (Matterhorn*/EMP507) of beans in temperate (Michigan) and tropical (Puerto Rico) climates. Fourteen QTL associated with resistance to E. fabae and E. kraemeri were identified on five chromosomes explaining up to 66.0% of the phenotypic variation for single resistance traits. A major QTL cluster associated with multiple resistance traits and closely linked to the P color gene was detected for both leafhopper species in multiple seasons under both choice and no‐choice treatments on Pv07 (LH7.1, LH7.2, LH7.3), thus validating a similar QTL identified in previous studies. A novel QTL (LH2.2) for E. fabae nymph counts, identified on Pv02 in three seasons, may be associated with antibiosis resistance. Resistance to each leafhopper species appears to be controlled by separate genetic mechanisms in common bean as there was little overlap of QTL regions between species. These QTL could be used to develop beans with leafhopper resistance as an alternative to costly chemical controls while reducing risks to the environment and human health.
SrTA10187 was fine-mapped to a 1.1 cM interval, candidate genes were identified in the region of interest, and molecular markers were developed for marker-assisted selection and Sr gene pyramiding. Stem rust (Puccinia graminis f. sp. tritici, Pgt) races belonging to the Ug99 (TTKSK) race group pose a serious threat to global wheat (Triticum aestivum L.) production. To improve Pgt host resistance, the Ug99-effective resistance gene SrTA10187 previously identified in Aegilops tauschii Coss. was introgressed into wheat, and mapped to the short arm of wheat chromosome 6D. In this study, high-resolution mapping of SrTA10187 was done using a population of 1,060 plants. Pgt resistance was screened using race QFCSC. PCR-based SNP and STS markers were developed from genotyping-by-sequencing tags and SNP sequences available in online databases. SrTA10187 segregated as expected in a 3:1 ratio of resistant to susceptible individuals in three out of six BCF families, and was fine-mapped to a 1.1 cM region on wheat chromosome 6DS. Marker context sequence was aligned to the reference Ae. tauschii genome to identify the physical region encompassing SrTA10187. Due to the size of the corresponding region, candidate disease resistance genes could not be identified with confidence. Comparisons with the Ae. tauschii genetic map developed by Luo et al. (PNAS 110(19):7940-7945, 2013) enabled identification of a discrete genetic locus and a BAC minimum tiling path of the region spanning SrTA10187. Annotation of pooled BAC library sequences led to the identification of candidate genes in the region of interest-including a single NB-ARC-LRR gene. The shorter genetic interval and flanking KASP™ and STS markers developed in this study will facilitate marker-assisted selection, gene pyramiding, and positional cloning of SrTA10187.
Conventional selected‐bulk breeding is a low cost means of advancing populations but requires years of selection in the field to generate fixed lines. Doubled haploid (DH) methods produce fixed lines quickly but without selection and at high cost. The ‘Minibulk’ system was developed to combine the speed of DHs with the population size and crossover opportunities of selected‐bulk breeding. Breeding populations of winter wheat (Triticum aestivum L.) were vernalized and advanced at high density in the greenhouse from the F2 to the F4 generation. F4 populations underwent visual selection in the field, and derived lines were genotyped for variants at photoperiod and vernalization alleles and across the genome using genotyping‐by‐sequencing. The number of crossover events and parental genome contributions were determined for recombinant inbred lines (RILs) within populations and among RILs across populations. During vernalization, seeds in all populations germinated and underwent vegetative growth, forming a dense seed mat that was transplanted directly into greenhouse pots. A 22‐h photoperiod accelerated development, and many populations reached physiological maturity as soon as five weeks after transplanting. Increasing the number of seeds planted from 300 in the F2 to 500 in the F3 increased the number of fertile spikes produced, thereby maintaining a larger population size. The number of crossovers detected differed significantly between populations and chromosomes, while the number of crossovers detected in each population was related to marker density. Adoption of the minibulk system by winter cereal breeding programs can lead to significant cost savings and acceleration of the breeding cycle.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.