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New greenhouse supports research on yellow rust in Nepal

December, 2004

On December 1, CIMMYT handed over a greenhouse to the Plant Pathology Division of the Nepal Agricultural Research Council (NARC). Built with the support of CIMMYT’s project on foliar pathogens and funded by Belgian Development Cooperation (DGCD), this greenhouse will help sustain research on wheat diseases, despite Nepal’s current social conflict.

At a ceremony in Khumaltar, CIMMYT regional pathologist Etienne Duveiller delivered the greenhouse keys to T.K. Lama, Chief of the Plant Pathology Division. The new facility will help NARC scientists screen for resistance in wheat against yellow rust, a potentially devastating disease in the hill areas of Nepal. Grain losses can soar to 30% when early outbreaks occur, as demonstrated by last year’s severe epidemic in parts of the Kathmandu Valley.

Replacing Outmoded Resistance

Due to the breakdown of resistance in popular varieties like Sonalika, which date back to the Green Revolution, yellow rust epidemics have occurred in Nepal since the mid-1980s. In 1997, a new strain of the rust pathogen became prevalent in the Nepal hills—a strain that is virulent against Yr9, a gene from rye that has conferred resistance to yellow rust in many improved wheats.

To develop disease resistant plants, breeders artificially inoculate fields of experimental varieties and select the individuals or families that survive and produce grain. With help from CIMMYT, advanced lines from Nepal are tested annually in Pakistan to ensure that promising genotypes are exposed to new pathotypes of yellow rust from western Asia. But research of this type in Nepal has suffered in recent years, mainly from a lack of inoculum to apply to experimental plants. First, insecurity in Nepal has caused severe financial constraints and reduced operations for national agricultural research scientists. Second, there is a lack of proper facilities to produce rust inoculum for the timely inoculation of breeders’ fields. An alternate approach used—collecting natural inoculum that survives in off-season wheat crops—became nearly impossible after a series of dry years eliminated this source of the pathogen and security restrictions made travel impossible in remote hilly regions. Finally, less than optimal moisture in the screening fields of Khumaltar, where the Plant Pathology Division is located, has necessitated repeated applications of fresh inoculum.

The timely production of inoculum in the new greenhouse will improve this situation. This greenhouse has a robust and simple cooling system to control temperature, as well as a misting system that guarantees proper humidity. It will allow both screening against yellow rust under optimal conditions and the multiplication of inoculum. Since the wheat season is just starting, researchers working on other diseases and crops will benefit from having inoculum ready for breeders’ plots in January.

Preserving Spores and Global Partnerships

In an important recent accomplishment, according to Duveiller, Senior Wheat Pathologist Sarala Sharma was able to produce fresh inoculum directly from leaf samples collected last season, using local methods and dried leaves. “This is the first time that she was able to preserve inoculum from last March,” says Duveiller. “Yellow rust must be kept alive for multiplication in the greenhouse and cannot be grown on artificial media. The main problem is that it is very sensitive to high temperatures. In Nepal, power failures, poor refrigeration, and no possibilities of vacuum preservation make it hard to keep spores.”

During the greenhouse opening ceremony, Sharma underlined the importance of the long-standing collaboration between NARC and CIMMYT. She acknowledged CIMMYT’s continuous support, initiated by former CIMMYT wheat pathologists Jesse Dubin and the late Eugene Saari, who encouraged scientists to collect inoculum from rust-prone areas as a way to record the disease’s incidence and spread. These surveys had continued with support from Duveiller until recently, when traveling by road became difficult. Also recognized at the ceremony were the benefits of training on yellow rust pathotyping that Nepali scientists had received at IPO-Wageningen, the Netherlands, and Shimla, India.

CIMMYT wheat pathologist, Etienne Duveiller, with colleagues in Nepal.

Similar work may become possible now in Nepal, according to Duveiller. “This greenhouse, built with Indian technology and including inexpensive but sturdy polyethylene sheets for siding, is another example of the importance CIMMYT ascribes to rust diseases on wheat in Nepal and south Asia,” says Duveiller. The center recently funded the installation of a sprinkler system for use in disease resistance experiments at Bhairhawa farm in the Tarai Plains, where the Nepal Wheat Research Program is based.

The greenhouse handover ceremony was combined with the farewell party for two NARC pathologists who retired recently, K. Shrestha and C.B. Karki. A recognized rust pathologist and longtime CIMMYT friend, Karki received his Ph.D. from Montana State University and attended the second Regional Yellow Rust Conference in Islamabad, Pakistan, in March 2004. Dr. K. Shrestha attended CIMMYT’s conference on helminthosporium blight in Mexico.

For more information: e.duveiller@cgiar.org