Bridging germplasm and mechanisms: screening for resistance and decoding defense strategies against rice gall midge (Orseolia oryzae Wood-Mason) in rice

Response of Rice Genotypes Carrying Gall Midge Resistance Genes against Asian Rice Gall Midge, Orseolia oryzae (Wood-Mason), in Mahabubabad, Telangana, India

Rice gall midge, Orseolia oryzae (Wood-Mason), is a major pest of rice that causes significant yield losses in India. The present study was conducted during Kharif 2023 at Krishi Vigyan Kendra, Malyal, Mahabubabad district, Telangana, to evaluate four rice genotypes carrying genes conferring resistance to gall midge (WGL-1119, IBT-WGL-2, Abhaya, and Aganni), together with TN-1 as a susceptible check, against the local gall midge population under natural infestation conditions. The experiment was laid out in a randomized block design with four replications. Gall midge incidence was assessed at 30, 50, and 75 days after transplanting (DAT) based on the percentages of plant damage and silver shoot damage, and the observations recorded at 50 DAT were used to score the genotypes according to the standard procedure. Significant differences were observed among the genotypes. Aganni, IBT-WGL-2, and WGL-1119 exhibited resistant reactions with low levels of infestation. At 50 DAT, Aganni recorded the lowest damage (2.50% plant damage and 0.52% silver shoots), followed by WGL-1119 (6.25% plant damage and 0.86% silver shoots) and IBT-WGL-2 (7.50% plant damage and 0.71% silver shoots). Abhaya showed moderate susceptibility, whereas the susceptible check, TN-1, recorded the highest infestation. Aganni and IBT-WGL-2 maintained stable resistance up to 75 DAT, whereas WGL-1119 showed a slight increase in plant damage but remained resistant based on silver shoot damage. Aganni and the pyramided lines IBT-WGL-2 (Gm4+Gm8) and WGL-1119 (Gm1+Gm4) were identified as promising sources of resistance to gall midge and as suitable resistant donors for breeding programmes. This is the first report on the response of these resistant genotypes to the gall midge population prevailing in Mahabubabad district, Telangana, India.

Distinct Resistance Groups in Rice Germplasm from Kerala Based on Antibiosis and Tolerance Traits to Brown Planthopper, Nilaparvata lugens (Stal)

Background: Brown planthopper (Nilaparvata lugens) is a major insect pest of rice that causes severe yield losses through direct feeding and hopperburn. The emergence of virulent populations and increasing concerns over insecticide resistance necessitate the identification of rice germplasm with effective host plant resistance for sustainable pest management. Aims: To identify rice germplasm accessions resistant to N. lugens by evaluating antibiosis and tolerance mechanisms and to classify the accessions based on their resistance responses. Study Design: Comparative laboratory screening of rice germplasm accessions using antibiosis and tolerance parameters, followed by multivariate analysis. Place and Duration of Study: Department of Agricultural Entomology, Kerala Agricultural University, Thrissur, Kerala, India, during 2023–2025. Methodology: Twelve rice germplasm accessions, together with the resistant check PTB 33 and susceptible check TN 1, were evaluated under controlled conditions. Antibiosis and tolerance were assessed using standard biological and plant response parameters. Data were analysed using analysis of variance, Spearman correlation, principal component analysis, and hierarchical clustering. Results: Significant differences were observed among the germplasm accessions for all antibiosis and tolerance parameters (P < .001). TGC 108 and UN 46 22K exhibited lower honeydew excretion (27.2 and 28.4 mm²), reduced nymphal emergence (99.4 and 114.6 nymphs/accession), prolonged developmental periods (21.2 and 19.4 days), delayed wilting (25.0 and 22.7 days), and lower functional plant loss index values (22.7 and 25.2), indicating strong antibiosis and tolerance. Principal component analysis explained 97.02% of the total variation, and hierarchical clustering grouped the germplasm into three distinct resistance categories. Conclusion: TGC 108 and UN 46 22K exhibited strong antibiosis and tolerance responses and emerged as promising donor sources for the development of brown planthopper-resistant rice varieties.

Evaluation of Local Rice Genotypes from Southwest Aceh for Resistance to Bacterial Leaf Blight (Xoo Strain VIII)

Local rice germplasm is a valuable genetic resource for developing bacterial leaf blight (BLB)-resistant and high-yielding rice cultivars. However, information on the resistance of Southwest Aceh local rice to Xanthomonas oryzae pv. oryzae (Xoo), particularly during the generative stage, remains limited. Previous studies have mainly focused on commercial cultivars or vegetative-stage screening, leaving the resistance potential of local germplasm at the reproductive stage largely unexplored. This study aimed to evaluate the resistance of local rice to BLB at the generative stage of plant growth. The research was conducted at Experimental Field, Teuku Umar University. West Aceh (4°08′33″ N; 96°11′54″ E). Fifteen local rice genotypes, together with resistant and susceptible control varieties, were evaluated following artificial inoculation with Xoo strain VIII. Disease resistance was assessed based on incubation period and lesion length, while agronomic performance was evaluated using key yield-related traits. Seven local genotypes Itam Tangke Lango, Jantong, Jempa Puteh, Manyam U, Pade Manggeng-1, Pade Manggeng-2, and Rangan Lango were classified as resistant based on lesion length. Among the evaluated genotypes, Sikleng exhibited superior agronomic performance, producing the highest number of productive tillers (27.50) and grains per panicle (317.73). The novelty of this study lies in evaluating Southwest Aceh local rice germplasm for bacterial leaf blight resistance at the generative stage using Xoo strain VIII while integrating disease resistance with yield-related agronomic traits. The identified resistant genotypes provide valuable donor parents for breeding BLB-resistant, high-yielding rice cultivars and contribute to sustainable rice production and regional food security.

Identification of Resistance Sources against Yellow Stem Borer (Scirpophaga incertulas Walker) in Rice under Field Conditions

Rice (Oryza sativa L.) is a crucial food crop, but its productivity is greatly affected by insect pests, particularly the yellow stem borer, Scirpophaga incertulas (Walker). This study evaluated rice cultivars for resistance to this pest under natural field conditions during the Rabi 2025-26 season at the Regional Agricultural Research Station (RARS), Warangal, Professor Jayashankar Telangana Agricultural University (PJTAU). Thirty rice cultivars, together with seven resistant and susceptible checks, were evaluated in a randomised block design (RBD) with two replications. Yellow stem borer (YSB) damage was recorded at the vegetative stage at 30 and 50 days after transplanting (DAT) and at the reproductive stage. Based on dead-heart incidence, five cultivars were classified as highly resistant, seven as resistant, ten as moderately resistant, seven as moderately susceptible, and one as susceptible. Based on white-ear incidence, five cultivars were highly resistant, seven were resistant, nine were moderately resistant, seven were moderately susceptible, and two were susceptible. WGL-1957 recorded the lowest dead-heart incidence and the highest grain yield, whereas IET 29877 recorded the lowest white-ear incidence and the second-highest grain yield. These resistant cultivars may serve as donors in breeding programmes for yellow-stem-borer resistance and may support integrated pest management strategies.

Deciphering the genetic and phenotypic bases of early vigor, anaerobic germination, and lodging resistance in rice (Oryza sativa L.) through bulked line analysis

Morphological and Molecular Screening for Bacterial Leaf Blight Resistance in Land Races of Rice (Oryza sativa L.)

Bacterial leaf blight (BLB) of rice, caused by Xanthomonas oryzae pv. oryzae, is a major constraint on rice production, and the use of resistant genotypes is an important approach to disease management. The present study screened 40 rice genotypes for BLB resistance using morphological evaluation and molecular markers linked to seven resistance genes: xa5, Xa7, xa8, Xa10, xa13, Xa21 and Xa33. Field screening was conducted at RARS, Maruteru, during kharif 2023 using artificial inoculation by the leaf-clipping method, and disease reactions were assessed according to the Standard Evaluation System. Morphological screening categorised entries as highly resistant, resistant, moderately resistant, susceptible or highly susceptible according to diseased leaf area. Molecular screening was performed using gene-linked markers to determine the presence of the target resistance genes. Nineteen genotypes were identified as carrying two or three BLB resistance genes. Phenotypic evaluation based on diseased leaf area showed variation in resistance among the 40 genotypes and supported the molecular screening results. Jaavepula-2, Basmati, Tulasi baso and Kundadam-2 carried three resistance genes, while Kalamuch and Loyamalli carried the Xa7 and Xa21 combination and exhibited phenotypic resistance. The combined morphological and molecular screening therefore identified rice genotypes with multiple BLB resistance genes that may serve as donor parents in marker-assisted breeding programmes aimed at improving BLB resistance in rice.