QTL mapping of root hair and acid exudation traits and their relationship to phosphorus uptake in common bean

Authors

Yan, X.; Liao, H.; Beebe, S.E.; Blair, M.W.; Lynch, J.P.

Source

Plant and Soil, Kluwer Academic Publishers, Volume 265, Issue 1/2, Netherlands, p.17-29 (2004)

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Abstract

The relationship between root-hair growth, acid exudation and phosphorus (P) uptake as well as the quantitative trait loci (QTLs) associated with these traits were determined for a recombinant inbred line (RIL) population derived from the cross of two contrasting common bean ( Phaseolus vulgaris L.) genotypes, DOR364 and G19833, which were grown in solution culture and under field conditions with low-P availability. In the solution-culture study, root-hair density, root-hair length, H ⁺ exudation and total acid exudation were measured. Substantial genotypic variability was observed for these traits and their response to P availability. The P-efficient parent G19833 had greater root-hair density, longer root-hair length, and greater exudation of H ⁺ and total acid than the P-inefficient genotype DOR364. These traits segregated continuously in the RIL population, with obvious tendency of trait transgression. Genetic analysis revealed that the root traits measured hadvarious heritabilities, with h _b ² ranging from 43.24 to 86.70%. Using an integrated genetic map developed for the population, a total of 19 QTLs associated with root hair, acid exudation and P-uptake traits were detected on 8 linkage groups. P uptake in the field was positively correlated with total acid exudation, basal root-hair length, and basal root-hair density. Acid-exudation traits were intercorrelated, as were root-hair traits. Total acid exudation was positively correlated with basal root-hair density and length. Linkage analysis revealed that some of the root-trait QTLs were closely linked with QTLs for P uptake in the field. We propose that marker-assisted selection (MAS) might be a feasible alternative to conventional screening of phenotypic root traits.