Assessment of Rice Amylose Content and Grain Quality Through Marker-Assisted Selection

Rice (Oryza sativa L.) is essential for global food security and sustains billions worldwide, emphasizing the need to improve production and quality. One key challenge in rice breeding is the inheritance and environmental sensitivity of amylose content, a starch component that influences the texture, water absorption, and firmness after cooking, which are crucial for market acceptance. While international markets prefer low-amylose varieties for their softness, intermediate- and high-amylose varieties are favored in Latin America for their firmness. The objective of this study was to develop a molecular quality assessment methodology that, combined with morphological and culinary evaluations, helps in the selection of rice varieties during the breeding process. First, ten Ecuadorian rice materials were evaluated for milling and culinary quality characteristics, revealing significant grain size, sterility, milling yield, cooking time, and texture variations. Amylose content (AC) is genetically regulated by the waxy gene and its allelic variants, affecting granule-bound starch synthase (GBSS) enzyme expression. Secondly, to classify rice varieties molecularly based on AC, the testing ten genotypes plus nine control varieties were analyzed using microsatellite (SSR) markers. The waxy molecular marker, combined with metaphor agarose gel electrophoresis (MAGE), proved effective for early-stage AC analysis, reducing variety selection costs and improving breeding efficiency. Additionally, a restriction enzyme protocol assay facilitated variety differentiation by selectively cleaving the waxy gene sequence at a specific single-nucleotide polymorphism (SNP) site, allowing for precise AC genetic classification. By integrating molecular techniques with traditional assessments, this study reveals that using marker-assisted selection in breeding programs, as well as supporting the identification and development of high-quality local rice varieties to meet market demands, improves production efficiency and optimizes the assessment of developing varieties under diverse environmental conditions.