The introgression of resistance to Tuta absoluta in tomato based on glandular trichomes

Tomato (Solanum lycopersicum L.) is one of the most important and consumed vegetables worldwide both in fresh and processed form. Among the main pests, the South American tomato pinworm (Tuta absoluta Meyrick, Lepidoptera: Gelechiidae) stands out as one that causes great damage to its production. Control is based essentially on intensive chemical applications which increases the production cost, besides promoting ecological imbalances and possible health problems for consumers and farmers. Among the plant defense mechanisms against herbivores pests are the glandular trichomes and their secondary metabolites that together can be poisonous, repellent, or trap insects and other organisms. In order to develop a resistant cultivar to T. absoluta, we introgressed a trichome-based resistance trait from the wild tomato (Solanum pennellii) into cultivated tomato. The wild tomato has the type IV glandular trichomes, the major site of biosynthesis for acylsugars, which have been consistently linked to broad-spectrum resistance to herbivorous arthropods of tomato. The backcross genotypes (F2BC2) come from a cross between the species S. pennellii access LA-716 (donor genome with high acylsugar content) and the commercial cultivar S. lycopersicum cv. Redencao (background genome with low acylsugar content). Eight genotypes with high recovery of the background genome were selected to identify and quantify the glandular and non-glandular trichomes as well as to assess their resistance to the T. absoluta. Direct correlations between the acylsugar content, number of type IV glandular trichomes and resistance to the South American tomato pinworm were observed, indicating that the desired trait from S. pennellii is inherited throughout the backcrosses. Two groups were formed among the analyzed genotypes: high and low levels of acylsugars. In the high-level group, the higher acylsugar content led to a better control of the pinworm in a similar way to the wild parent (resistant). The overall analysis of our data shows that the genotypes RVTA-2010pl#232 and RVTA-2010pl#257 have the greatest potential to develop tomato lines with desirable commercial traits for the processing industry besides resistance to the South American tomato pinworm.