Zarir Saeidi - Agricultural and Natural Resources Research Center, Chaharmahal & Bakhtiari, Iran

An experiment was conducted to study the inheritance of type IV glandular trichomes and its relationto two-spotted spider mite (TSSM) resistance in cross Lycopersicon esculentum Mill × L. pennellii‘LA 2580’. Parents and their F1 and F2 progenies were raised under natural conditions. Five weeksafter transplanting, fully expanded young leaves were collected and used for estimating density of typeIV glandular trichomes and TSSM resistance. Subsequently, two-month-old plants were challengedwith TSSM (50 adults and 150 eggs). After two weeks, they were scored for damage index (0 to 6scale). The estimated heritability in broad sense was high (93%) for density of type IV glandulartrichomes. Statistical analyze showed that two dominant unlinked genes control the presence of typeIV trichomes in the hybrids. There was an over expression of type IV glandular trichomes in F1 plants.Density of type IV trichomes in F2 individuals showed a broad range of variability (0 to 35trichomes/mm²). There was a significant positive relationship between density of type IV glandulartrichomes and resistance to TSSM.

Lycopersicon esculentum, L. pennellii, Glandular trichomes, Tetranychus urticae, Inheritance, Resistance