A national organization identifies a problem to be solved or a new opportunity to exploit with tropical fruits. It then decides whether it has the in-house capacity to execute the task or should collaborate with another organization. For the latter case, a potential collaborator would be an international center such as CIAT, with which the national organization can enter a contract to conduct a research and development project. For CIAT, most research of this type in Colombia has, so far, been conducted with the national Ministry of Agriculture and Rural Development (MADR, its Spanish acronym).

Lulo Regeneration and Transformation

Lulo (Solanum quitoense) is an Andean crop that is renowned not only for the delicate flavor of its fruit, but also for being notoriously difficult to produce because of the numerous diseases and pests that attack it. Traditional breeding methods have been used to incorporate resistance to nematodes—a serious problem—from wild species. But the quality of the fruit is still not satisfactory despite several generations of backcrossing to commercially grown material.

Genetic transformation appears an attractive option for incorporating resistance to specific diseases or pests while maintaining fruit quality. Consequently, MADR has commissioned CIAT to develop transformation techniques for lulo. The capacity to regenerate whole plants from differentiated tissue is an essential step in genetic transformation. Based on work carried out with other Solanaceae, protocols were developed to regenerate lulo plants from leaf tissue. The protocols were then improved to ensure high rates of success on a routine basis. A spin off from this work will be the ability to rapidly produce clonal material of lulo.

At the same time, we used Agrobacterium tumefaciens to introduce the GUS gene into lulo tissue. Although this gene is of no commercial use, it demonstrates that we now have techniques for introducing useful genes into lulo tissue.

Banana Bacterial Blight in Plantain

Banana bacterial blight (moko in Spanish), caused by Ralstonia solanacearum, is a devastating disease of plantain. It causes losses of more than US$5.8 million per year in Colombia. MADR contracted CIAT to study the genetic variation of the causal agent and to identify disinfectants that could be used to prevent the disease spreading through tools. The blight bacterium showed wide variability, particularly in those isolates obtained from soil samples. Various disinfectants, including several natural products, were identified as potentially effective.

Citrus Anthracnose

Citrus anthracnose causes heavy losses in Colombia by attacking a wide range of different plant species. MADR contracted CIAT and CORPOICA to evaluate genetic variation in Colletotrichum acutatum, the causal agent of citrus anthracnose. Isolates were collected from many citrus species over a wide range of conditions and geographic zones in Colombia, and analyzed by AFLP. The fungus showed considerable genetic variation, but no consistent relationship between isolate cluster and host species or collection zone.