ISHS Acta Horticulturae 487: VI International Symposium on Processing Tomato & Workshop on Irrigation & Fertigation of Processing Tomato
IDENTIFICATION AND SELECTION OF PROCESSING TOMATO GENOTYPES RESISTANT TO TOSPOVIRUS |
| Authors: | L.V. Resende, E. Ferraz, J.G.E.de França, H.A. Quilombo, A.A.S. da Silva |
| Keywords: | Plant breeding, Lycopersicon esculentum, cv. Stevens, TSW-10, Sw-5 |
| Abstract:
The identification, characterization and selection of processing tomato lines resistant to tospovirus, to be used as commercial cultivars or materials to produce F1 hybrids, under greenhouse and natural infection conditions was the objective of this research-work. F7 lines from the crosses (IPA-5 x TSW-10) x IPA-5, seeded on speedling trays with 128 cells were mechanical inoculated with tospovirus isolates, in Pernambuco, Brazil. A randomized block with 3 replications was the experimental design used. Using buffer 0.01M phosphate, pH 7.0 and sodium sulfite, under stage of definitive double leaf, the tomato plants were inoculated. The lines were characterized as homozygous resistant, heterozygous and susceptible homozygous. Symptom of the individual plants was evaluated, according to a note scale. A Chi-square test was used to compare each note class of the progenies to the note frequency of Santa Clara (positive control) and TSW-10 (negative control- resistant). Of all tested progenies, 60% showed fully homozygous to resistance; 40% were heterozygous and only IPA-5, IPA-7 and Santa Clara showed to be susceptible. Some homozygous progenies presented medium severity higher than 1.0 due to incomplete penetrance of allele Sw-5, responsible for the resistance. The tested progenies presented a high level of resistance against tospovirus under natural infection condition, during the entire cycle of production. About 25.8% of the tested progenies presented only one injured plant during evaluation period: 32.26% presented a progressive incidence, related to number of infected plants. The greatest number of plants with the symptom was observed between the 3rd and 5th week of the period of evaluation that happened when plants were 40 days after transplanting. The positive controls IPA-5 and IPA 7 presented both the highest indexes of incidence between the 3rd and 5th week, reaching 100% of incidence at the 8th week of evaluation period. Agricultural characteristics of those homozygous resistant progenies were evaluated, highlighting the IPA-5 RT-22 (pl#04) line which will be released as a tospovirus resistant cultivar. | |
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