Wheat varieties susceptible to new strains of yellow rust fungus : study

Wheat varieties susceptible to new strains of yellow rust fungus : study

New Delhi, May 8 (India Science Wire): Agriculture scientists have cautioned about likely spread of extremely virulent strains of fungus that causes yellow rust in wheat to which currently used wheat cultivars show high susceptibility. The situation is particularly grim as the bread wheat cultivar HD267 that currently occupies 10 to 12 million hectare area is susceptible to these new strains.

By Dr. Aditi Jain

Yellow rust disease of wheat
: a disease caused by fungus Puccinia

Yellow rust disease of
wheat,
also known as stripe rust of wheat, is a disease caused by
fungus Puccinia frequently found in cold wheat growing regions such as North
Western Plains Zone and Northern Hills Zone. This infection which causes
reduction of kernel numbers per spike and decreases the weight of wheat kernels
is capable of causing up to 70% decline in wheat yields.

Currently used wheat
cultivars in India have a part of rye chromosome which confers resistance to
yellow rust and powdery mildew disease. Over the years, the strains of fungus
which can infect these resistant cultivars have become prominent and are
spreading. Although fungicides such as propiconazole, tebuconazole and
triadimefon are being used for combating yellow rust of wheat, the imparting
genetic resistance to plants is preferred as it is cheap, effective and
eco-friendly way of fighting plant diseases.

Scientists from ICAR-Indian
Institute of Wheat and Barley Research
(IIWBR) at Shimla and Karnal
have identified three new extremely virulent strains of thisfungus
capable of causing severe loss to wheat productivity in India. First detected
in India during 2013-2014, these three strains (110S119, 238S119 and 110S84)
are now aggressively growing in numbers.

To better understand evolution of this resistance, scientists have studied composition of a part of their genomes to understand their relationship with other fungal strains. Such a genetic cataloguing  of pathogens also aids in keeping a track of spread and damage caused by a particular strains.

Further, scientists tested
56 newly released varieties of wheat for resistance against these new strains.
For this, the seeds of these varieties were grown and the seedlings were
infected with these strains. To their dismay, none of the newly released variety
was found to be resistant to all resistant strains.

Scientists also screened 64 new advanced lines of wheat for resistance and found that 11 of them were resistant to these newly emerged resistant fungal strains. Deployment of these advance lines can help to fight these newly emerged pathogens. 

“To combat these new
strains, we are ready with the resistance sources and at the same time
regularly screening ‘advance varietal trial’ material. Our regional station
keep a watch on the occurrence of new races and are designing strategies for management
of new virulent strains,” said Dr. Subhash Chander Bhardwaj,
member of  the research team and a scientist
at IIWBR Shimla, while speaking to India Science Wire.

The study results have been published in Journal of Plant Pathology. The research team from Shimla included Om Prakash Gangwar, Subodh Kumar, Pramod Prasad and Subhash Chander Bhardwaj; and Prem Lal Kashyap and Hanif Khan from Karnal.

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