Bacterial crown rot-tolerant papaya being developed in ACIAR-PCAARRD project

Dr. Pablito M. Magdalita (left) discusses the potential bacterial crown rot (BCR)-tolerant lines inside a screen house of IPB-UPLB (Photo by the Crops Research Division)

Papaya plants tolerant to bacterial crown rot (BCR) are being developed in a project funded by the Australian Centre for International Agricultural Research and the Philippine Council for Agriculture, Aquatic and Natural Resources Research and Development of the Department of Science and Technology (DOST-PCAARRD).

During a visit at the Institute of Plant Breeding (IPB) of the University of the Philippines Los Baños (UPLB), researchers of the project examined the potential BCR-tolerant lines grown inside the screen house. New stems, termed as regrowth, appeared in some of the infected plants two to three months after complete collapse of the crown of the test plants that were treated with the BCR pathogen.

According to Dr. Pablito M. Magdalita of UPLB, the occurrence of regrowth as a form of tolerance to bacterial crown rot is a promising technology in identifying papaya selections tolerant to BCR.

The project, Integrated disease management strategies for the productive, profitable and sustainable production of high quality papaya fruit in the southern Philippines and Australia, is being implemented by the University of the Philippines Los Baños (UPLB), Bureau of Plant Industry (BPI), and Del Monte Philippines.

BCR causes the leaves of the papaya plant to turn yellow and eventually die. It causes discoloration and water-soaking of the stem and crown of the plant. The disease has affected many parts of Southern Philippines.

Dr. Nanditha Pathania, collaborating scientist from the Department of Agriculture, Fisheries and Forestry in Queensland, discussed the process in generating the potential BCR-tolerant lines.

A joint project review was also conducted between IPB-UPLB researchers and DOST-PCAARRD staff. During the review, Dr. Magdalita explained that the 58 new papaya accessions screened for BCR resistance in Tranca, Bay, Laguna have remained uninfected since December 2014.

Dr. Magdalita discussed the different activities relative to the development of papaya genotypes that are resistant or tolerant to BCR: purification and advancement of BCR tolerant lines; hybridization of BCR with PRSV tolerant lines; selection of new BCR tolerant lines; and natural screening for BCR resistance, acquisition of seeds, and preparation of seedlings for third batch of screening.

Dr. Pathania recommended to look at the relationship between time of field planting and BCR incidence. She also suggested to test for lignified tissues at different parts of the plant to identify the part most vulnerable to bacteria, especially with factors that influence bacterial growth such as cold weather, rainfall, and wind that could damage the tissues.

Source:  http://www.pcaarrd.dost.gov.ph/home/portal/index.php/quick-information-dispatch/2799-bacterial-crown-rot-tolerant-papaya-being-developed-in-aciar-pcaarrd-project