LINES of popular tomato varieties from the Philippines with resistance to Tomato Leaf Curl Virus (ToLCV)-Laguna isolate hold promise for reviving tomato’s robust production.
Tomato was the leading vegetable crop in the country in terms of area planted until 1990. The peak of decline in the area of production in 1997 was primarily due to pests and diseases, as well as unfavorable climatic conditions especially during off-season months.
Virus diseases, including ToLCV, are considered the most damaging to tomato production worldwide causing 50-percent to 100-percent yield loss.
Use of chemicals to stop the vector insect proved to be costly and does not warrant sustainable protection. Moreover, the strategy can be hazardous both to human health and environment.
The use of resistant varieties offers the most effective and practical strategy to overcome the disease. While breeding initiatives to virus resistant varieties have been going on, the lack of varieties with durable resistance against multiple virus diseases remains a concern to farmers. At present, there are no commercial varieties grown in the Philippines with durable resistance to major virus diseases such as ToLCV.
A two-year project to develop tomato breeding lines resistant to ToLCV was completed by a project team composed mainly of local scientists at the Institute of Plant Breeding of the University of the Philippines Los Baños, namely Dr. Josefina Narciso, Dr. Melquiades Reyes, Dr. Lolita Dolores and Alma Canama.
With financial support from the Department of Agriculture Biotech Program, the research team developed the candidate ToLCV-resistant lines from local tomato varieties by interbreeding local varieties with ToLCV-resistant tomato lines acquired from the Asian Vegetable Research and Development Center-The World Vegetable Center.
ToLCV-resistance in the parental lines, hybrids and the derived lines from the initial hybrids were verified by exposing the plants to the ToLCV-Laguna isolate and by marker-assisted selection (MAS).
MAS can predict at a very early stage, such as a seedling, whether a plant will grow to express a trait of interest just by the mere presence or absence of gene markers.
Gene markers are short unique DNA sequences near the DNA sequence of the gene responsible for a desired physical characteristic/trait in each generation of plants produced. In this case, markers for genes responsible for the resistance to ToLCV were detected in the genetic make-up of the tomato lines.
Lines rated as highly resistant due to absence or very minimal observed symptoms of infection and detected for presence of ToLCV-resistance genes through gene markers were considered candidate ToLCV-resistant breeding materials.
Use of the promising resistant breeding materials may improve production yield and income of thousands of tomato growers.