Genetic mapping of brown plant hopper resistance from Oryza rufipogon (Griff.)
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Date
2019
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Punjab Agricultural University, Ludhiana
Abstract
Brown planthopper (BPH) Nilaparvata lugens (Stal) is one of the most serious insect-pest of rice
accounting for the loss up to 52% of annual production. Under high infestation, complete drying and plant
death occurs causing “hopper burn”. The primary strategy for controlling BPH is the application of
chemical insecticides, which is already proven detrimental not only to the environment, but also to human
health. On this account host-plant resistance serves as an important strategy to reduce the damage caused
by BPH. Out of 1003 wild species germplasm accessions screened against BPH, O. rufipogon acc.
CR100441 has shown consistent resistance reaction (score 1-3) during 3 years of screening under
greenhouse conditions. The F1 plant was obtained by making a cross of O. rufipogon acc.CR100441 and
PR122. The BC2F2 plants were generated by further back crossing with PR122 and selfing then after. The
BC2F2 plants were screened by the standard seedbox technique at seedling stage against BPH biotype 4.
The BC2F2 plants were scored phenotypically on a 0-9 scale according to the Standard Evaluation System
(IRRI, 1996) as 1-3 resistance, 5 moderate resistance, and 7-9 susceptible plant. From 276 BC2F2 plants,
66 plants were found to be resistant (1-3 score) and 210 plants (5, 7 and 9 score) were susceptible which
fitted in 3:1 ratio (susceptible: resistant) indicating the recessive nature of the BPH resistance gene.
Genotyping using polymorphic microsatellite markers between PR122 and O.rufipogon acc.CR100441
spanning all the 12 chromosomes of rice was done. The QTL governing BPH resistance was identified on
the short arm of chromosome 4 between marker interval RM551 and RM6659. The RM16335 was peak
marker, with LOD score of 10.8 and 35.23% contributing towards the phenotypic variation. This
information can be used for further fine mapping and cloning of the gene. The pre-breeding BC2F4 lines
with BPH resistance can be further utilize in breeding programmes aimed in development of resistant
cultivars.
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