No abstract

Rice (Oryza sativa L.) is a staple food for over half of the world's population. However, rice grain quality is one of the major problems facing rice breeders across the world. Cooked rice elongation, cooked rice expansion, and water absorption have been identified as some of the parameters used in gauging rice grain quality. Biomarkers such as proteins or metabolites can be used to differentiate among a pattern of variations among various samples (e.g., various locations within a plant, various germplasm accessions); consequently, they present a type of internal validation for a given biological state. In the present study, we investigated the putative metabolite biomarkers associated with the variation of cooked rice elongation for Hua Jing Xian 74 (receptor), Basmati 370 (donor), and five hybrid lines resulting from a cross of these parent lines. We also investigated their cooked rice expansion and water absorption properties. After carrying out cooked rice elongation studies, metabolomics studies, correlation analyses, V-plot analyses, and thorough searches in public metabolite databases (Metlin, Massbank and KEGG), and in-house secondary metabolite database, we identified a metabolite with molecular weight of 280.25 and retention time of 6.4 min as a putative biomarker associated with cooked rice elongation in the varieties investigated. We also discovered that changes in cooked rice elongation and changes in cooked rice expansion follow a similar pattern; however, it appears that cooked rice elongation and cooked rice expansion do not affect water absorption in these rice lines. Our findings may facilitate the improvement of the cooked rice elongation of hybrids resulting from the crosses of Basmati 370 and Hua Jing Xian 74. Our results also offer interesting insight into cooked rice elongation, cooked rice expansion, and water absorption.

The cooking and eating qualities of rice are some of the problems facing by rice producers and consumers around the world. In this study we investigated the cooking and eating qualities of Basmati 385 and Hua Jing Xian 74. Both are rice cultivars with different phenotypic traits.The results show that Basmati 385 increased by an average of 102.14% after cooking while Hua Jing Xian 74 increased by an average of 69.91% after cooking. Basmati 385 had a pasting temperature of 78°C, while Hua Jing Xian 74 had a pasting temperature of 84°C. However, Hua Jing Xian 74 had a final viscosity of 4,686 cP while Basmati 385 had a final viscosity of 3,514 cP. The amylose contents of the two cultivars were also different; Hua Jing Xian 74 had an amylose content of 19.4%, while that of Basmati 385 was 18%. We also discovered that the starch granule morphology of the two cultivars were remarkably different.The lower pasting temperature of Basmati 385 positively correlated with good cooking qualities of rice. However, Hua Jing Xian 74 appears to have relatively better eating qualities due to its higher viscosity and higher amylose content. It would be pertinent to do more research about hybrid lines resulting from a cross of Hua Jing Xian 74 and Basmati 385, to see if they possess the good cooking qualities of Basmati 385 and the good eating qualities of Hua Jing Xian 74.

A reduction in light intensity by 27%, 47%, or 73% shading significantly increased percent variegation (relative amount of nongreen area per leaf) and significantly decreased fresh and dry weight, but did not appreciably affect leaf nutrient content of Peperomia obtusifolia L. Nutrient treatments had no consistent effect on variegation or fresh and dry weight.