Root system development and architecture in various genotypes of the Solanaceae family

We present an extensive, dynamic, and quantitative study of the root system architecture of Solanaceae based on 29 genotypes from three important groups (aubergines, capsicums, and tomatoes). Quantitative traits were essentially obtained from measurements made on high resolution images of different plant parts at several stages. The developmental schema was common to all genotypes. Several traits showed significant genetic variations: root apical diameter (reflecting meristem size), interbranch distances, slopes of the regression lines of elongation rate versus apical diameter, and ratios of diameters of laterals to mother roots. On all genotypes, the initial root system was complemented by a strong adventitious system emerging near the plant collar, made up of a set of fast growing roots with large apical diameters. Correlations between traits were evidenced within the root systems on one hand (e.g., interbranch distance and diameter ratio of laterals to their mother) and between shoot and root on the other hand (e.g., leaf area growth rate and root elongation rate). They revealed both trade-offs in developmental processes and coordination between plant parts. Beyond these results, we demonstrated the importance of characterizing phenotypes through multiple criteria, considering the whole plant and including late stages.