Comprehensive Review on Grain Quality Enhancement and Development of Disease-Resistant

Rice (Oryza sativa L.), the seed of life, holds immense nutritional, cultural, and medicinal importance, especially in Asia, where it serves as a staple food for over 90% of the population (Tripathi et al., 2020). While white rice is most commonly consumed, it loses significant nutritional components, such as fiber, vitamins, and minerals, during the refining process. In contrast, pigmented rice varieties—such as black, red, brown, and purple rice—retain their bran layers and are rich in essential nutrients, antioxidants, and bioactive compounds, including anthocyanins and γ-oryzanols. These properties make colored rice increasingly popular among health-conscious consumers for addressing micronutrient deficiencies, such as anaemia and zinc deficiency, as well as chronic diseases through its antioxidant intake. Biofortification to enhance zinc and iron content, coupled with improvements in protein (especially glutelin), starch quality, and fiber, is crucial for addressing malnutrition and supporting sustainable health outcomes. Equally important is managing the significant biotic stress—Bacterial Leaf Blight (BLB)—caused by Xanthomonas oryzae pv. oryzae, which has historically caused yield losses up to 80% and significantly affected grain quality. In India, major outbreaks have been reported in states like Andhra Pradesh, Haryana, Punjab, and Maharashtra. Management strategies encompass genetic, cultural, biological, chemical, and mechanical approaches, with genetic resistance being the most eco-friendly and sustainable. Over 40 resistance (R) genes (e.g., Xa21, xa5, xa13) have been identified, and marker-assisted selection and gene pyramiding have proven effective in developing resistant varieties such as IRBB60. These gene combinations not only provide long-lasting resistance but also preserve grain nutritional traits. Thus, integrating breeding programs for enhanced grain nutritional quality and robust disease resistance offers a dual strategy to improve rice productivity, ensure food security, reduce environmental degradation, and deliver health benefits to consumers. This approach aligns with global efforts to achieve sustainable agriculture and improve nutritional outcomes. Keywords: Oryza sativa, Grain quality improvement, Micronutrients, Bacterial leaf blight, Marker-assisted selection