GS 3 : Science & Technology – Biotechnology

Why in News?

Rice blast, caused by a fungus Magnaporthe oryzae, is one of the major diseases of the rice crop. Now, researchers from ICAR-National Rice Research Institute (NRRI), Odisha have mapped out the diverse genes in rice that help in disease resistance.

Rice Blast Disease:

• Rice blast caused by fungus Magnaporthe oryzae,is generally considered the most important disease of rice worldwide because of its extensive distribution and destructiveness under favourable conditions.
• Rice blast can affect most of the rice plant with the exception of the roots. The fungus can infect plants at any growth stage.
• Symptoms can be either lesions or spots. Their shape, colour and size vary depending on varietal resistance, environmental conditions and the age of the lesions.
• Rice blast is the most important disease of rice worldwide. Under favourable conditions, the disease can results in total crop failure.

Background:

• From 1980-1987, seven blast endemics have occurred in India causing severe losses. Fungicides are very expensive, harmful for the environment and inappropriate application can cause health issues.
• Researchers around the globe have been on a hunt for resistant genes against the pathogen and so far, more than 100 resistance (R) genes in the rice genome have been identified.
• The rapid changes in pathogen virulence pose a constant challenge to the success of existing blast-resistant rice varieties.
• Therefore, there is always a need to identify new broad-spectrum blast resistant genes/alleles in rice germplasm such as landraces, wild rice, etc,

Findings:

• Researchers from ICAR-National Rice Research Institute (NRRI), Odisha have mapped out the diverse genes in rice that help in disease resistance.
• The present study showed that the rice landraces collected from north-eastern states of India had the highest resistance.
• The researchers found the presence of 24 previously pin-pointed resistant genes in the 161 rice landraces. The landraces were found to harbour 5-19 resistant genes.
• The landraces from Tripura had the highest number of resistant genes, followed by those from Maharashtra.
• The study also pointed out that rice varieties in the same ecological conditions can have different resistant/susceptible behaviours.