Phenotyping and pattern analysis of key root morphological traits in a white clover mapping population.

Abstract

Application of molecular marker technology to identify Quantitative Trait Loci (QTL) associated with key root traits is expected to enhance white clover breeding programmes, to improve characteristics such as increased efficiency in phosphorous (P) uptake and summer moisture stress tolerance. The phenotypic diversity for a range of root morphological traits among 500 mapping family (F1) progeny was characterised using plants grown hydroponically. The root traits measured were: dry weight, length, surface area, diameter, volume, numbers of root tips and root forks. Variance component analysis indicated significant (P<0.005) genotypic variance among the 500 progeny for all the root traits measured. For most root traits the differences between the minimum and maximum values also indicated a large range of phenotypic variation among the 500 progeny. Pattern analysis helped identify progeny groups as well as providing a graphical representation of the association among the root traits. One of the progeny groups contained members with root trait morphology indicating the potential to enhance soil penetration per unit volume of soil, which could result in improved soil P uptake. The genotype-by-root trait matrix of individual progeny means generated from this study will be used for preliminary QTL analysis.