Scientists in Hyderabad-based CSIR-Centre for Cellular and Molecular Biology (CCMB) and ICAR-Indian Institute of Rice Research (IIRR) have identified a rice line with enhanced natural resistance to a major pest ‘Yellow Stem Borer’ (YSB).
When tested in field conditions during different seasons, the resistant line showed an average damage of less than 10% as against 40-60% damage in the susceptible line. The resistant line has been registered as a germplasm at ICAR-National Bureau of Plant Genetic Resources and will go through rigorous field trials to ascertain its suitability for field cultivation.
The resistant rice line was further characterised by using cutting-edge technologies like genomics, transcriptomics and metabolomics, to gain deeper insights into the molecular mechanisms governing the YSB resistance.
The research team from CCMB and IIRR comprise C. G. Gokulan, Umakanth Bangale, Vishalakshi Balija, Suneel Ballichatla, Gopi Potupureddi, Deepti Rao, Prashanth Varma, Nakul Magar, Karteek Jallipalli, Sravan Manthri, A. P. Padmakumari, Gouri S. Laha, L. V. Subba Rao, Kalyani M. Barbadikar, Raman Meenakshi Sundaram, Hitendra K. Patel, M Sheshu Madhav and Ramesh V. Sonti.
The scientists pointed out that rice is the staple food of about half the people of the world and among the various pests and microorganisms, the YSB poses a serious threat resulting in up to 20-70% loss in the crop yield. YSB insects are ‘monophagous’ — feeding only on rice.
The female moths lay eggs on the leaf tips and after hatching, the larvae move towards a suitable site on the stem to bore and further feed on the tissue material inside the stem affecting productivity. The pest infestation is observed as different symptoms based on the growth stage of the plants.
During the vegetative growth stage, the larvae bores the base of the stem, and feeds towards the top — causing the stem to turn brownish and finally die, leading to “dead hearts”. Infestation during the reproductive stage of rice occurs at the peduncle thus leading to no grain filling, resulting in empty panicles called “white ears”.
Plants deploy various strategies to fend off invading organisms including physical barriers and specialized chemical compounds. However, the pest breaks the plant defence barriers resulting in disease or infestation. This forces farmers to rely on chemical interventions for pest management leading to environment degradation, they explained.
The research had revealed modulation of particular pathways and functions crucial for YSB resistance in rices. This could help in transfer of YSB resistance to susceptible rice varieties through traditional breeding approaches. This work is considered to be one of the first to study the detailed molecular mechanisms that govern rice-yellow stem borer interaction and has provided valuable knowledge and avenues for future research.
An important resource for YSB resistance breeding has also been generated by this study which has the potential to reduce crop loss and can significantly bring down the usage of chemical insecticides. The research has been published in the latest issue of the journal - Theoretical and Applied Genetics https://doi.org/10.1007/s00122-024-04628-7
