Phenotypic and genotypic characterization of grain quality in US and Latin American rice and implications for breeding.

Background: Latin America is the largest importer of US rice, accounting for 40% of total exports in 2020. However, since 2010, concerns have been raised by Latin American importers regarding the quality of US rice, particularly about the high chalk content of milled rice and the stickiness of cooked rice. This study aimed to understand the differences in grain quality between US long-grain rice and rice produced and exported from Latin America and to explore potential breeding strategies to improve US rice quality for the Latin American export market.

Results: A panel of 88 southern US rice varieties was evaluated for visual quality (grain length, width and chalk content) and cooking quality (amylose content, gelatinization temperature and pasting properties). These were then compared to 21 popular Latin American rice samples. Amylose content emerged as the primary factor differentiating US and Latin American rice, significantly influencing cooking characteristics. Genotypic analysis of the Waxy and Alk genes showed a strong correlation with amylose content and gelatinization temperature, effectively distinguishing US rice from Latin American rice.

Conclusion: The research identified key phenotypic differences between US and Latin American rice, particularly in amylose content, which impacts cooking quality. The study successfully used these findings to deploy a breeding strategy, crossing US germplasm to develop new varieties with grain quality similar to that preferred in Latin America. This work provides a foundation for creating target product profiles that align US rice quality with the preferences of the Latin American market. © 2025 Society of Chemical Industry.