scholarly journals Disparate Genetic Variants Associated With Distinct Components of Cowpea Resistance to the Seed Beetle Callosobruchus Maculatus

Author(s):  
Frank J Messina ◽  
Alexandra M Lish ◽  
Zachariah Gompert

Abstract Cowpea ( Vigna unguiculata ) is an important grain and fodder crop in arid and semi-arid regions of Africa, Asia, and South America, where the cowpea seed beetle, Callosobruchus maculatus , is a serious post-harvest pest. Development of cultivars resistant to C. maculatus population growth in storage could increase grain yield and quality and reduce reliance on insecticides. Here, we use a MAGIC (multi-parent, advanced-generation intercross) population of cowpea consisting of 305 recombinant inbred lines (RILs) to identify genetic variants associated with resistance to seed beetles. Because inferences regarding the genetic basis of resistance may depend on the source of the pest or the assay protocol, we used two divergent geographic populations of C. maculatus and two complementary assays to measure several aspects of resistance. Using polygenic genome-wide association mapping models, we found that the cowpea RILs harbor substantial additive-genetic variation for most resistance measures. Variation in several components of resistance, including larval development time and survival, was largely explained by one or several linked loci on chromosome 5. A second region on chromosome 8 explained increased seed resistance via the induction of early-exiting larvae. Neither of these regions contained genes previously associated with resistance to insects that infest grain legumes. We found some evidence of gene-gene interactions affecting resistance, but epistasis did not contribute substantially to resistance variation in this mapping population. The combination of mostly high heritabilities and a relatively consistent and simple genetic architecture increases the feasibility of breeding for enhanced resistance to C. maculatus.

2019 ◽  
Vol 112 (5) ◽  
pp. 2418-2424
Author(s):  
Frank J Messina ◽  
Alexandra M Lish ◽  
Zachariah Gompert

Abstract Cowpea, Vigna unguiculata (L.) Walp., serves as a major source of dietary protein in many tropical and subtropical regions around the world. To identify loci associated with agronomically desirable traits, eight elite cowpea cultivars were systematically inter-crossed for eight generations to yield 305 recombinant inbred lines. Here, we investigated whether these founder parents also possess resistance to the seed beetle Callosobruchus maculatus (F.), a highly destructive post-harvest pest. We estimated larval survival in seeds, egg-to-adult development time, adult mass at emergence, and seed acceptance for oviposition. Survival varied significantly among cowpea cultivars, but the pattern was complicated by an unexpected source of mortality; on three cultivars, mature larvae in a substantial fraction of seeds (20–36%) exited seeds prematurely, and consequently failed to molt into viable adults. Even if such seeds were eliminated from the analysis, survival in the remaining seeds varied from 49 to 92% across the eight parents. Development time and body mass also differed among hosts, with particularly slow larval development on three closely related cultivars. Egg-laying females readily accepted all cultivars except one with a moderately rugose seed coat. Overall, suitability ranks of the eight cultivars depended on beetle trait; a cultivar that received the most eggs (IT82E-18) also conferred low survival. However, one cultivar (IT93K-503-1) was a relatively poor host for all traits. Given the magnitude of variation among parental cultivars, future assays of genotyped recombinant progeny can identify genomic regions and candidate genes associated with resistance to seed beetles.


2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Carlos A. Avila ◽  
Thiago G. Marconi ◽  
Zenaida Viloria ◽  
Julianna Kurpis ◽  
Sonia Y. Del Rio

Abstract The tomato-potato psyllid (TPP), Bactericera cockerelli, is a vector for the phloem-limited bacterium Candidatus Liberibacter solanacearum (Lso), the causative agent of economically important diseases including tomato vein-greening and potato zebra chip. Here, we screened 11 wild tomato relatives for TPP resistance as potential resources for tomato (Solanum lycopersicum) cultivar development. Six accessions with strong TPP resistance (survival <10%) were identified within S. habrochaites, S. pennelli, S. huaylasense, S. chmielewskii, S. corneliomulleri, and S. galapagense. Two S. pennelli and S. corneliomulleri accessions also showed resistance to Lso. We evaluated recombinant inbred lines (RILs) carrying resistance from S. habrochaites accession LA1777 in the S. lycopersicum background and identified major quantitative trait loci (QTLs) responsible for adult TPP mortality and fecundity in several RILs carrying insertions in different chromosomes, indicating the polygenic nature of these traits. Analysis of a major resistance QTL in RIL LA3952 on chromosome 8 revealed that the presence of Lso is required to increase adult TPP mortality. By contrast, the reduced TPP oviposition trait in LA3952 is independent of Lso. Therefore, resistance traits are available in wild-tomato species, although their complex inheritance and modes of action require further characterisation to optimise their utilisation for tomato improvement.


2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Lara Pereira ◽  
Miguel Santo Domingo ◽  
Valentino Ruggieri ◽  
Jason Argyris ◽  
Michael A. Phillips ◽  
...  

Abstract Melon is as an alternative model to understand fruit ripening due to the coexistence of climacteric and non-climacteric varieties within the same species, allowing the study of the processes that regulate this complex trait with genetic approaches. We phenotyped a population of recombinant inbred lines (RILs), obtained by crossing a climacteric (Védrantais, cantalupensis type) and a non-climcteric variety (Piel de Sapo T111, inodorus type), for traits related to climacteric maturation and ethylene production. Individuals in the RIL population exhibited various combinations of phenotypes that differed in the amount of ethylene produced, the early onset of ethylene production, and other phenotypes associated with ripening. We characterized a major QTL on chromosome 8, ETHQV8.1, which is sufficient to activate climacteric ripening, and other minor QTLs that may modulate the climacteric response. The ETHQV8.1 allele was validated by using two reciprocal introgression line populations generated by crossing Védrantais and Piel de Sapo and analyzing the ETHQV8.1 region in each of the genetic backgrounds. A Genome-wide association study (GWAS) using 211 accessions of the ssp. melo further identified two regions on chromosome 8 associated with the production of aromas, one of these regions overlapping with the 154.1 kb interval containing ETHQV8.1. The ETHQV8.1 region contains several candidate genes that may be related to fruit ripening. This work sheds light into the regulation mechanisms of a complex trait such as fruit ripening.


BMC Ecology ◽  
2020 ◽  
Vol 20 (1) ◽  
Author(s):  
Dmitry Kutcherov

Abstract Background The thermal plasticity of life-history traits receives wide attention in the recent biological literature. Of all the temperature-dependent traits studied, developmental rates of ectotherms are especially often addressed, and yet surprisingly little is known about embryonic responses to temperature, including changes in the thermal thresholds and thermal sensitivity during early development. Even postembryonic development of many cryptically living species is understood superficially at best. Results This study is the first to estimate the exact durations of developmental stages in the cowpea seed beetle C. maculatus from oviposition to adult emergence at five permissive constant temperatures from 20 to 32 °C. Early embryonic development was tracked and documented by means of destructive sampling and subsequent confocal imaging of fluorescently stained specimens. Late embryonic and early larval development was studied with the use of destructive sampling and light microscopy. Well-resolved temporal series based on thousands of embryos allowed precise timing of the following developmental events: formation of the blastoderm; formation, elongation, and retraction of the germ band; dorsal closure; the onset and completion of sclerotization of the cuticle; hatching, and penetration of the first-instar larva into the cowpea seed. Pupation and adult eclosion were observed directly through an incision in the seed coat. The thermal phenotype of C. maculatus was found to vary in the course of ontogeny and different stages scaled disproportionately with temperature, but pitfalls and caveats associated with analyses of relative durations of individual stages are also briefly discussed. Conclusion Disproportionate changes in developmental durations with temperature may have important implications when study design requires a high degree of synchronization among experimental embryos or when the occurrence of particular stages in the field is of interest, as well as in any other cases when development times need to be estimated with precision. This work provides one of the first examples of integration of embryological techniques with ecophysiological concepts and will hopefully motivate similar projects in the future. While experiments with Drosophila continue to be the main source of information on animal development, knowledge on other model species is instrumental to building a broader picture of developmental phenomena.


2017 ◽  
Vol 284 (1855) ◽  
pp. 20170132 ◽  
Author(s):  
Liam R. Dougherty ◽  
Emile van Lieshout ◽  
Kathryn B. McNamara ◽  
Joe A. Moschilla ◽  
Göran Arnqvist ◽  
...  

Traumatic mating (or copulatory wounding) is an extreme form of sexual conflict whereby male genitalia physically harm females during mating. In such species females are expected to evolve counter-adaptations to reduce male-induced harm. Importantly, female counter-adaptations may include both genital and non-genital traits. In this study, we examine evolutionary associations between harmful male genital morphology and female reproductive tract morphology and immune function across 13 populations of the seed beetle Callosobruchus maculatus . We detected positive correlated evolution between the injuriousness of male genitalia and putative female resistance adaptations across populations. Moreover, we found evidence for a negative relationship between female immunity and population productivity, which suggests that investment in female resistance may be costly due to the resource trade-offs that are predicted between immunity and reproduction. Finally, the degree of female tract scarring (harm to females) was greater in those populations with both longer aedeagal spines and a thinner female tract lining. Our results are thus consistent with a sexual arms race, which is only apparent when both male and female traits are taken into account. Importantly, our study provides rare evidence for sexually antagonistic coevolution of male and female traits at the within-species level.


Agronomy ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1285 ◽  
Author(s):  
Yuliya Genievskaya ◽  
Saule Abugalieva ◽  
Aralbek Rsaliyev ◽  
Gulbahar Yskakova ◽  
Yerlan Turuspekov

Leaf rust (LR) and stem rust (SR) pose serious challenges to wheat production in Kazakhstan. In recent years, the susceptibility of local wheat cultivars has substantially decreased grain yield and quality. Therefore, local breeding projects must be adjusted toward the improvement of LR and SR disease resistances, including genetic approaches. In this study, a spring wheat segregating population of Pamyati Azieva (PA) × Paragon (Par), consisting of 98 recombinant inbred lines (RILs), was analyzed for the resistance to LR and SR at the seedling and adult plant-growth stages. In total, 24 quantitative trait loci (QTLs) for resistance to rust diseases at the seedling and adult plant stages were identified, including 11 QTLs for LR and 13 QTLs for SR resistances. Fourteen QTLs were in similar locations to QTLs and major genes detected in previous linkage mapping and genome-wide association studies. The remaining 10 QTLs are potentially new genetic factors for LR and SR resistance in wheat. Overall, the QTLs revealed in this study may play an important role in the improvement of wheat resistance to LR and SR per the marker-assisted selection approach.


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