Tomato mutants and introgression lines provide evidence for a role of flavonoids in lateral root and root hair development.
Wake Forest University
Flavonoids are secondary metabolites that regulate plant development and reproduction. Flavonoid abundance is environmentally regulated by drought, light, and oxidant stress. Understanding the genetic controls of flavonoid synthesis and how they affect plant physiology will be useful in the breeding of crop plants that adapt better to our changing global climate. To determine how flavonoids affect lateral root and root hair development in tomato, we examined mutants and introgression lines (ILs). The tomato mutant anthocyanin reduced (are) has a mutation in the gene encoding an enzyme in flavonoid synthesis, reducing flavonoid synthesis. This mutant has elevated levels of the flavonoid precursor naringenin, and lower than wild-type levels of downstream flavonoids: kaempferol, quercetin, myricetin, and anthocyanins. are has fewer lateral roots and greater numbers of root hairs than its wild type parent. These biochemical and developmental phenotypes are reversed by complementation with a functional copy of the missing gene. We also examined flavonol levels and root development using introgression lines (ILs) into which a small region of the chromosome of an ancestral tomato plant, Lycopersicon pennelli (Lp), has been crossed into the Lycopersion esculetum genome. We identified lines with altered numbers of lateral roots. IL 2-5, forms increased numbers of lateral roots, and contains Lp genes that are linked to flavonoid biosynthesis. Quantification of transcripts encoding flavonoid enzymes and flavonoid metabolites in these ILs are in progress. The ILs will allow us to identify genes that modulate lateral root and root hair development and flavonoid biosynthesis in tomatoes to understand how flavonoids control these important developmental processes.