MOLECULAR SCREENING OF F₁ PLANTS FOR THREE GALL MIDGE RESISTANCE GENES IN THE ELITE RICE CULTIVAR TELANGANA SONA

Abstract

Telangana Sona is a popular rice cultivar known for its super fine, short-slender grains and low glycemic index (GI = 51.72). However, its susceptibility to the Asian rice gall midge (Orseolia oryzae Wood-Mason) poses a constraint to stable production. Marker-assisted introgression of complementary resistance genes offers a promising approach to improve gall midge resistance while retaining the desirable characteristics of this elite cultivar. In the present study, Telangana Sona and the donor line RMSGm3 were molecularly characterized using gene-specific functional markers targeting the gall midge resistance genes gm3, Gm4 and Gm8. The markers gm3del3, LRR-del and PRP distinguished the donor and recurrent parents based on their allele sizes. RMSGm3 exhibited resistance-associated alleles of approximately 250, 350 and 300 bp, respectively, whereas Telangana Sona carried the corresponding susceptible alleles of approximately 550, 600 and 350 bp. A total of 150 F₁ seeds were obtained from the cross Telangana Sona × RMSGm3, of which 120 F₁ plants were screened during rabi 2024–25. Thirteen plants exhibited the expected heterozygous allelic patterns at all three target loci and were identified as triple-positive F₁ plants, accounting for 10.83% of the screened population. The selected plants retained the characteristic short-slender, super fine grain phenotype of Telangana Sona, while their plant height and heading time were broadly comparable to those of the recurrent parent. These findings establish a molecularly confirmed F₁ population carrying alleles associated with all three target resistance loci, providing a foundation for subsequent marker-assisted backcrossing and gene pyramiding in the Telangana Sona genetic background. However, molecular confirmation of the target loci alone does not establish effective or durable resistance. Further evaluation of advanced progenies, including confirmation of gene inheritance and resistance screening against diverse gall midge populations, is necessary to validate the resistance potential of the developed material.