Evaluation and Characterization of Indigenous Rice (Oryza sativa L.) Landraces Resistant to Brown Planthopper Nilaparvata lugens (Stål.) Biotype 4

Abstract Evaluation and identification of resistant donors for brown planthopper (BPH) Nilaparvata lugens (Stål.), an economically important insect pest of rice, is a continuous process to develop new resistant rice varieties. However, several rice landraces of north-eastern India are not yet characterized for BPH resistance. In the present study, a set of 218 rice landraces were screened in both greenhouse and open-field conditions for three consecutive years, and thereafter forty selected promising entries were explored to evaluate their phenotypic and genotypic reactions against BPH biotype 4. Based on phenotypic evaluations, 5 landraces were identified as resistant, while 31 were moderately resistant, and grouped under the major cluster I and II, respectively, in a circular dendrogram. Antixenosis and antibiosis studies of these landraces divulged that, compared to the susceptible check variety, resistant landraces exhibited the lowest feeding rate, survival, and nymphal and adult settling, but higher frequency of unhatched eggs of BPH. Un-infested resistant landraces registered higher levels of ascorbic acid, oxalic acid and crude silica, however, elevated levels of total free amino acid, potassium and crude silica were observed under BPH herbivory. During the analysis of genetic diversity through 21 BPH resistance gene-linked SSR markers, the selected landraces were categorized into five major clusters at 10 unit distance by the scale of similarity. Most of the resistant landraces were grouped under the major cluster IV revealing their similar genetic history, whereas some were grouped with moderately resistant landraces displaying their genetic variation. The present study focuses on identifying new donors having BPH resistance resources which could be useful in genomic studies for the development of BPH biotype 4 resistant rice varieties.