Development of yellow leaf curl disease resistant and high yielding tomato (Solanum lycopersicum L.) hybrid through marker-assisted selection and diallel crosses

Tomato Yellow Leaf Curl Disease (TYLCD) is a highly destructive disease in the most tomato cultivated areas globally, while becoming uncontrollable in tropical and subtropical regions. TYLCD is triggered by several Begomovirus species and it is transmitted by whitefly (Bemisia tabaci). TYLCD is controlled mainly by vector targeted pesticides, which leads to evolve pesticide resistant vector biotypes. Thus, resistant tomato varieties are the most sustainable way to control TYLCD. This study aimed to develop tomato F1 hybrids with TYLCD resistance/ tolerance and higher yield. TYLCD causative Begomovirus in the study was confirmed as Pepper yellow leaf curl virus which has close homology with tomato yellow leaf curl virus. Forty tomato accessions were evaluated and characterized based on 15 traits of yield and yield components, morphological, physiochemical and TYLCD symptom severity in a randomized complete block design (RCBD) with 3 replications at Field 15, Institute of Tropical Agriculture and Food Security, Universiti Putra Malaysia and the best 9 accessions were selected as parental lines to produce F1 crosses. The selected 9 accessions out of initial 40 were used to produce F1 hybrids and, succeeded 18 F1 hybrids and their 9 parental lines were screened to determine the presence of TYLCD resistant/tolerance namely, Ty 1, Ty 2, Ty 3, Ty 4, ty 5 and Ty 6 genes using gene specific primers. The results revealed the F1 hybrids, T4 × T6, T6 × T4 and T7 × T15 possess homozygous resistance (RR) for Ty 1, Ty 2 and Ty 3 alleles with most promising tolerance to TYLCD, while T4 ×T8, T4 ×T9, T7 ×T5, T8 × T4, T8 × T6, T8 × T9, T9 × T4 and T9 × T6 hybrids possess homozygous resistance only for Ty 3 and Ty 2 genes, which is expected to have substantial potential for TYLCD tolerance. The 18 F1 hybrids with their 9 parental lines were evaluated in a glass house over 2 planting cycles in randomized complete block design (RCBD) with 3 replications. Highly significant differences were observed among all genotypes at p ≤ 0.01 for all the traits. Out of the 18 F1 hybrids and their 9 parental lines, only 10 F1 hybrids and their 5 parental lines were applicable in to half diallel analysis. Estimated general combining ability (GCA) revealed parental lines T4 and T2 had the highest values in yield per plant trait, 276.34 g/plant and 112.11 g/plant respectively, whereas T8 is the best in terms of disease incidence (GCA: -0.17) and index for disease severity (GCA: -0.11) toward TYLCD resistance. Specific combining ability (SCA) analysis revealed two hybrids, namely T2×T4 (SCA: 838.90 g/plant) and T4×T8 (SCA: 424.83 g/plant) as the best performers in terms of yield traits, while hybrid T6×T9 was identified as the best in terms of disease incidence (SCA: -0.08) and index for disease severity (SCA: -0.008) on TYLCD resistance. Hybrid T4 ×T8 has superior yield (2.06 kg/plant) and TYLCD resistance is highly recommended for further large-scale evaluation before release as a new developed variety for commercial cultivation in Malaysia.

Text 118192.pdf Download (1MB) Official URL or Download Paper: http://ethesis.upm.edu.my/id/eprint/18361

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