Researchers develop high protein wild rice

The study is scheduled for publication later this month in the ACS Journal of Agricultural and Food Chemistry. Hari Krishnan and colleagues from the University of Missouri, Tamil Nadu Agricultural University and the USDA created a hybrid by crossing a commonly cultivated rice species called Oryza sativa with a wild species, Oryza nivara. The product showed a protein content of 12.4 percent, which is 18 percent and 28 percent higher than those of the parents. Screening germplasm collections of cultivated rice has shown that protein content tends to range from 5 to 18 per cent, with an average of 9.5 percent. The increase in protein content was dependent on the genetic background of the rice variety used in the hybridization, with a significant increase in prolamins and glutelins being mainly responsible. The fact that the study involves wild rice means the variety has added benefits. According to the report, wild species of rice allow for much genetic variation for crop improvement. "Besides the valuable genes for disease resistance that the wild species have provided for rice improvement, recent studies have shown that these wild species could also provide favorable alleles for the improvement of yield and yield-related traits,"​ says the report. Molecular analysis suggested the increase in protein content was not a result of chromosomal rearrangements or transposable element activation, at least in the chromosomal regions containing seed storage protein genes. Analysis of the F2 segregating population showed that the inheritance of the increased protein content was polygenic in nature. The researchers concluded that the hybrid could provide initial breeding material for new rice genotypes that could combine types with superior cooking quality with those of high protein content. Rice is a staple diet for billions of people worldwide, with annual global production in 2007/08 projected at 421m tons (milled basis), demonstrating a gradual increase. Global consumption continues to outpace production and is expected to grow 5.5m tons to 424m tons. The report says the enrichment of protein in rice would have a positive impact on millions of poor and malnourished people in developing countries. It claims that researchers have long been investing efforts into improving the protein content of rice, but they have been largely unsuccessful, despite reports on the ability to combine high protein content and high yield in other cereals such as wheat and oats. The report says: "The lack of success may have been caused by the universal complexity of the inheritance of endosperm traits. In addition, seed protein content tends to have low heritability due to the significant environmental effects and to show negative correlation with yield and some eating/cooking quality criteria." ​Source: Journal of Agricultural and Food Chemistry​ Published online ahead of print doi: 10.1021/jf071776n "​Interspecific Rice Hybrid of Oryza sativa × Oryza nivara Reveals a Significant Increase in Seed Protein Content" ​Authors: Ahmed A Mahmoud, S Sukumar and Hari B Krishnan