Recently, the scientific community has been buzzing with a discovery made by the Centre for Plant Molecular Biology (CPMB). Their research shed light on how a bacterium named Xoo interacts with rice plants and leads to disease.
Key Aspects about Xoo
Xoo, a short term for Xanthomonas oryzae pv. oryzae, is a gram-negative bacteria causing a grave bacterial leaf blight disease in rice, also known as Bacterial blight. This pathogen has been a significant problem, with its infection leading to considerable yield losses in rice cultivation worldwide.
The Transmission Process of the Disease
The infection begins from the leaf sheath and slowly spreads to mature leaves via the water flow under optimal temperature and high humidity conditions. This process is known as Vascular disease. The typical flooding of rice fields during the growing season facilitates the spread of Xoo within crops. Moreover, the bacteria can also travel through the wind to other crops and rice paddies.
Impact on Other Crops
The impact of Xoo isn’t limited to rice. It has been observed to infect other plants like Leersia oryzoides, better known as rice cut-grass, Chinese sprangletop, common grasses, and several kinds of weeds.
Existing Preventative Measures
Currently, the primary method of protecting against rice bacterial blight is cultivating rice varieties that have resistance to Xoo infection. Over 30 resistance genes have been discovered in rice plants, including Xa1 to Xa33. Some of these genes, like Xa21, have even found their way into commercial rice strains.
New Approach to Tackling the Problem
Scientists at the Centre for Plant Molecular Biology have proposed a new approach. They are working on identifying and developing specific molecules derived from either the Xoo bacterium or infected rice cell walls. Preliminary research shows that treating rice with cellulase, a cell wall degrading enzyme produced by Xoo, could induce rice immune responses and protect it from subsequent infections.
Rice’s Favored Growing Conditions
Rice is best grown in temperatures between 22-32°C and high humidity, with a deep clayey and loamy soil. Moreover, regions with around 150-300 cm of rainfall prove to be ideal for rice growth.
Major Rice-Growing Regions
Prominent rice-growing regions include Assam, West Bengal, coastal regions of Odisha, Andhra Pradesh, Telangana, Tamil Nadu, Kerala, Maharashtra, Uttar Pradesh, and Bihar. Increased irrigation networks have also allowed for rice cultivation in lesser rainfall areas such as Punjab, Haryana, western Uttar Pradesh, and parts of Rajasthan.
Rice Diseases
Diseases in rice are typically caused by bacteria, viruses, or fungi. Some notable diseases include Sheath blight (caused by the fungus Rhizoctonia solani), Brown Spot (damaging fungal disease), Tungro (caused by two viruses transmitted by leafhoppers), Bakanae (Seedborne fungal disease), and Blast (caused by the fungus Magnaporthe oryzae).
Gram-Negative Bacteria
Gram-negative bacteria are a group that can cause infections like pneumonia, bloodstream infections, wound or surgical site infections, and meningitis. These bacteria display multiple drug resistance and can pass on genetic materials enabling other bacteria to become drug-resistant.
About Centre for Plant Molecular Biology
The CPMB is one of the seven Centers of Excellence in India, where it functions as a hub for plant molecular biology’s research and development. Their work is focused on understanding plant life’s molecular basis and contributing to advancements in the agricultural industry.
