ISHS Acta Horticulturae 637: XXVI International Horticultural Congress: Advances in Vegetable Breeding
MEASURING THE EFFECT OF QUANTITATIVE TRAIT LOCI ON VASCULAR MORPHOLOGY AND DEVELOPMENT IN THE TOMATO STEM |
| Authors: | G.L. Coaker, D.M. Francis |
| Keywords: | Lycopersicon, power analysis, vascular anatomy, vascular transition, sampling strategy, quantitative trait loci mapping, Solanaceae |
| Abstract:
The vascular tissue of higher plants undergoes a transition in the hypocotyl between two highly differentiated structures, the root and shoot. This transition was studied in tomato by investigating the genetic basis of morphological variation between Lycopersicon esculentum and L. hirsutum LA407. Our analysis concentrated on morphology in stem cross sections, and we detected heritable genetic differences in inbred backross lines (IBLs) containing chromosome donor segments from L. hirsutum LA407. IBL 2353 contained a donor segment from chromosome 2 and retained features of the LA407 stem vascular morphology. An experimental power analysis was employed to determine the optimal strategy to measure vascular trait genetic and environmental variation in F2:3 families derived from IBL 2353 x L. esculentum. The power analysis estimated the variance associated with molecular markers for experiments with different levels of within and between family replication. The conclusion of this analysis is that four to five individuals within each family and a total of 20 families per marker class would be sufficient to minimize variance associated with molecular markers. Subsequent marker-trait analysis of vascular structure in the IBL 2353 F2:3 families showed significant (0.0001 ≤ 0.0375) associations between markers on chromosome 2 and the size of primary vascular bundles, the shape of the vascular system, and the thickness of secondary vascular tissue. These analyses provide an objective approach to determine optimal sampling strategies and suggest the distal portion of chromosome 2 in LA407 contains a locus or loci affecting vascular morphology and development. | |
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