Burton A; Johnson J; Foerster J; Hanlon MT; Kaeppler SM; Lynch JP; Brown KM.


Theoretical and Applied Genetics, Vol 128, Issue 1, pp 93-106

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Root anatomy is directly related to plant performance, influencing resource acquisition and transport, the metabolic cost of growth and the mechanical strength of the root system. Ten root anatomical traits were measured in three recombinant inbred populations of maize (intermated B73xMo17 [IBM], Oh43xW64a [OhW], and Ny821xH99 [NyH]). Traits were evaluated in roots from 4-week old plants grown in a greenhouse, and included areas of cross-section, stele, cortex, aerenchyma, and cortical cells, percentages of the cortex occupied by aerenchyma and cells, and counts of cortical cells and cell files. Significant phenotypic variation was observed for each of the traits. Maximum values were typically 7-10 times greater than minimum values for a given trait within a population. Means and ranges were similar for the OhW and NyH populations for all traits, with the exception of greater variation for cortical cell and cell file counts in the NyH population. Compared to the other two populations, the IBM population had lower mean values for the majority of traits, but a 50% greater range of variation for aerenchyma area. A principal component analysis showed a similar trait structure for the three families, with clustering of area and count traits. Allometric relationships were observed for the aerenchyma traits in the three populations. Strong correlations were observed among area traits in the cortex, stele and cross-section. The aerenchyma and percent living cortical area traits were independent of any other traits. Six QTL were identified for four of the traits, across the three populations. The phenotypic variation explained by the QTL ranged from 4.7% (root cross-section area, OhW population) to 12.0% (percent living cortical area, IBM population). Genetic variation for root anatomical traits can be harnessed to increase abiotic stress tolerance and provide insights into mechanisms controlling phenotypic variation for root anatomy.