Genetical studies on leaf curl virus resistance in tomato (Lycopersicon esculentum Mill.)

Abstract

An investigation was carried out in tomato to study the genetics of TLCV resistance and yield attributes, establish strainal differences in TLCV if any identify/confirm tomato leaf curl virus resistance through graft transmission. The salient findings of the present investigation are given below: TLCV resistance is governed by two complementary genes in the resistance parent RP1 (4-1/3) and it is controlled by recessive gene in the parent RP2 (55-3/7). The artificial whitefly inoculation is advantageous once field screening as it advances the expression of TLCV symptoms by weeks. Major contribution of dominance x dominance epistasis was observed for the inheritance of number of fruits, average fruit weight and fruit yield per plant in all the three crosses studied (SP1 x RP1, SP1 x RP2, SP2 x RP2). High magnitude of phenotypic coefficient of variation coupled with high genetic advance as percent of mean and low heritability (narrow sense) was observed for all the characters studied viz., number of fruits, average fruit weight and fruit yield per plant in all three crosses. Maximum frequency of transgressive segregants with TLCV resistance and fruit size (70 g and above) were observed in the crosses SP1 x RP1 compared to the other crosses viz., SP1 x RP2 and SP2 x RP2. Four different types of leaf curl symptoms could be differentiated based on symptom expression on a common genotype Arka Saurabh. They are termed as TLCV group A, TLCV group B, TLCV group C and TLCV group D. these were considered to be due to distinct TLCV strains. Five accession of L. Peruvianum (EC 251615, LA 1954, LA 2151, LA 2959 and PA 128659), two accessions of L. Chelense (LA 2729 and LA 1969) and three interspecific derivatives (4-1/3), RP2 (55-3/7) and 73-1/3) were found to be persistently resistant to TLCV.