Genome-wide association mapping and agronomic impact of cowpea root architecture

Abstract

Genetic analysis of data produced by novel root phenotyping tools was used to establish relationships between cowpea root traits and performance indicators as well between root traits and Striga tolerance. Selection and breeding for better root phenotypes can improve acquisition of soil resources and hence crop production in marginal environments. We hypothesized that biologically relevant variation is measurable in cowpea root architecture. This study implemented manual phenotyping (shovelomics) and automated image phenotyping (DIRT) on a 189-entry diversity panel of cowpea to reveal biologically important variation and genome regions affecting root architecture phenes. Significant variation in root phenes was found and relatively high heritabilities were detected for root traits assessed manually (0.4 for nodulation and 0.8 for number of larger laterals) as well as repeatability traits phenotyped via DIRT (0.5 for a measure of root width and 0.3 for a measure of root tips). Genome-wide association study identified 11 significant quantitative trait loci (QTL) from manually scored root architecture traits and 21 QTL from root architecture traits phenotyped by DIRT image analysis. Subsequent comparisons of results from this root study with other field studies revealed QTL co-localizations between root traits and performance indicators including seed weight per plant, pod number, and Striga (Striga gesnerioides) tolerance. The data suggest selection for root phenotypes could be employed by breeding programs to improve production in multiple constraint environments.

Investigation on Various Aboveground Traits to Identify Drought Tolerance in Cowpea Seedlings

“…Research aiming at identifying the most suitable plant morphology and root architecture for enhancing drought tolerance has been extensively investigated in cowpea (Ajayi et al, 2018;Burridge et al;. In this study, the effects of plant architecture on enhancing drought tolerance were limited by growing cowpea within sterility polypropylene boxes, which explained the absence of path Fig.…”

A multi‐parent advanced generation inter‐cross (MAGIC) population for genetic analysis and improvement of cowpea (Vigna unguiculata L. Walp.)

“…QTLs detected in the MAGIC population combined with existing knowledge of QTL regions and haplotypes can be applied to develop novel combinations of QTLs by intercrossing the best MAGIC RILs, providing super trait‐donor lines for use in breeding programs. QTLs for many key traits were already mapped in bi‐parental and diversity populations where certain MAGIC parents were used in the crosses, such as seed size (Lucas et al ., ), heat tolerance (Lucas et al ., ), drought tolerance (Muchero et al ., ) and root architecture (Burridge et al ., ) and resistance to foliar thrips (Lucas et al ., ), aphids (Huynh et al ., ), Fusarium wilt disease (Pottorff et al ., ), root‐knot nematodes (Huynh et al ., ), ashy stem blight or charcoal rot disease caused by Macrophomina phaseolina (Muchero et al ., ), viruses (Ouédraogo et al ., ) and the parasitic weed Striga gesnerioides (Ouédraogo et al ., ). It is therefore possible to track positive haplotypes contributed by different MAGIC parents in each MAGIC line and then intercross the best lines to develop ideotypes.…”

Reduction in Root Secondary Growth as a Strategy for Phosphorus Acquisition

“…ANOVA, Tukey's honestly significant difference, and regression analysis were performed, with significant effects considered at P # 0.05. Because plants grown under high P were larger than those grown under P stress, allometric relationships between root phenotypes and shoot mass were explored as described by Burridge et al (2017). The relationship between the decadic logarithm of the root phene and shoot biomass was fitted by linear regression.…”