526 Assessment of Rice Genotypes for Brown Plant Hopper Resistance Using Microsatellite Markers B.Vijaya Lakshmi, B.Srinivas, M.Vinay Kumar and D.Vijay Andhra Pradesh Rice Research Institute and Regional Agricultural Research Station Maruteru – 534122, West Godavari Dt., A.P., India For correspondence - bvlaprri@yahoo.com Abstract Phenotypic response of the 16 rice genotypes to brown plant hoppers (BPH) was evaluated at flowering stage under field conditions. The results indicated that genotypes were classified into five groups from score 1 to score 9. A total of 88 alleles were detected by 37 polymorphic markers with an average of 2.17. Polymorphic information content (PIC) value varied from 0.92 for RM 483 to 0.98 for RM 84, with an average of 0.95. An efficient separation of 16 rice genotypes based on SSR data into three groups was achieved by using unweighted pair group method with arithmetic means (UPGMA) clustering procedure based on genetic similarity expressed by the Jaccard similarity coefficient (JSC). Genotypes that are derivatives of genetically similar type clustered more together. The results also indicated that land races which are potential sources for biotic stress exhibited wide range of reaction from score 1 (slight drying) to score 9 (all plants apparently dead) to brown plant hopper screening and therefore very useful for rice breeding programs, especially for genetic mapping studies and eventually for application of marker-assisted selection (MAS). From this study it was concluded that mapping population could be developed by using PTB 33 and BM 71 as donors to introgress genes for BPH resistance into cultivated high yielding rice cultivars Key words: Brown plant hopper, Genetic diversity, Rice genotypes, SSR markers, variation Introduction Rice is a staple food for one-third of the worlds population and is grown on more than 148 million ha in wide range of ecosystems under varying temperature and water regimes. Most of the Worlds rice is cultivated and consumed in Asia, which constitutes more than half of the global population. Many biotic and abiotic stresses are continuing threat to rice productivity and sustainability. The major challenge is to overcome these constraints and produce high yielding rice varieties with multiple resistances to biotic and abiotic stresses possessing improved grain quality and nutritive value. Among the biotic stress, the brown plant hopper (BPH) Nilaparvata lugens Stal. is a serious insect pest of rice in Asia, causing severe yield losses in rice growing areas. It damages the crop by direct feeding and indirectly by acting as a vector for transmitting rice grassy stunt virus (RGSV) and yellow dwarf viral diseases. Under severe infestation, it causes complete death of crop popularly known as “hopper-burn” causing 100 % yield loss and this emerged as the major pest in tropical Asia during Current Trends in Biotechnology and Pharmacy Vol. 4 (1) 526-534 January 2010. ISSN 0973-8916 Rice genotypes for brown plant hopper