Leaf trichome diversity, acylsugar concentration, and their relationships to leaf area in Solanum galapagense

Abstract

Glandular trichomes are physical and chemical barriers used by some tomato wild relatives to confer resistance against insect pests and diseases transmitted by them. Solanum galapagense has been identified as one of the potential sources of insect pest resistance. The present study aimed to examine the trichome diversity and acylsugar concentration of 26 accessions of S. galapagense along with one cultivated tomato (S. lycopersicum) and one cherry tomato (S. l. cerasiforme) cultivar. The results revealed large phenotypic variation among S. galapagense accessions for all studied traits. The S. galapagense accessions had significantly higher trichome types IV density on the adaxial and abaxial surfaces of the leaf and greater acylsugar concentration but a smaller leaflet area than the cultivated tomato. The selected cherry tomato line represents greater trichome type IV density and acylsugar concentration than other groups. The acylsugar concentration was positively associated with trichome type IV but negatively associated with trichome type V on both leaf surfaces. DNA markers revealed the presence of two previously identified whitefly-resistance alleles in S. galapagense accessions. This study will support breeding programmes aiming to improve insect pest resistance in tomato cultivars using crop wild relatives.