ISHS Acta Horticulturae 487: VI International Symposium on Processing Tomato & Workshop on Irrigation & Fertigation of Processing Tomato
BREEDING TOMATOES FOR RESISTANCE TO WHITEFLY-TRANSMITTED GEMINIVIRUS WITH BIPARTITE GENOME IN BRAZIL |
| Authors: | L. de B. Giordano, I.C. Bezerra, P.T.O. Ferreira, C.R. Borges Neto |
| Keywords: | Lycopersicon spp., inoculation, sources of resistance |
| Abstract:
Major outbreaks of whitefly-transmitted geminivirus on tomatoes were observed after 1994 and the presence of geminivirus with bipartite genome was detected. Up to now, TYLCV (monopartite genome) has not been detected in Brazil. All tomato cultivars grown in Brazil are susceptible to geminivirus and breeding for disease resistant cultivars seems to be a promising approach. Various levels of resistance are present in wild Lycopersicon species and considerable effort has been made worldwide toward breeding resistant cultivars. Variable degrees of resistance have been found in L. pimpinellifolium, L. cheesmanii, L. hirsutum, L. peruvianum and L. chilense. Since 1995, several Lycopersicon accessions, representing four tomatoes species, were screened for resistance to a geminivirus isolate, with bipartite genome, from Brasilia-DF. Plants were inoculated with viruliferous whiteflies in individual insect-proof cages made of PVC tubes, with 15 cm of diameter and 20 cm high. One end of the tube was closed with muslin tissue and an average of 10 viruliferous whiteflies was used per plant. The screened genotypes were examined for the presence of viral DNA and for symptom development during 28 days after inoculation. Resistant genotypes were found in L. peruvianum (CNPH-784, CNPH-786 and CNPH 787), L. chilense (LA 1967), L. pimpinellifolium (LA 1342) and L. esculenium (TY-52; Multichiltyle 95; Chiltyle 93-3). Most of the resistant genotypes harbored the virus without showing symptoms. On the other hand, LA 1967 showed no disease symptom and the presence of viral DNA was detected in only one out of 10 inoculated plants, suggesting a different mechanism of resistance. | |
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