Rice is the primary food for more than 3 billion people around the world. New research, funded by USDA’s Cooperative State Research, Education, and Extension Service, may allow scientists to improve the nutritional value of rice, affecting the health of more than 70 million of the world’s poorest people in developing countries.

Researcher Zhaohua Peng and colleagues at Mississippi State University and Ohio State University determined that chromatin plays an essential role in the control of endosperm sizes and grain quality. The results obtained in this study are applicable not only to rice, but other cereal crops as well in improving grain yield and nutritional quality.

The endosperm portion of grain is an important component in determining the nutrient content for most cereal crops as it provides growing plant nutrition, such as starch, oils and protein. This makes endosperm an important source of nutrition in the human diet as well.

Chromatin structures store genetic information and control gene expression in cells. In chromatin, a piece of DNA wraps around a group of basic proteins called histones to form a structure similar to the coil of telephone cord. When proteins interact with the chromatin, it adjusts the tightness of the DNA and histone interaction. Genes positioned in loosely packaged chromatin regions are usually active and genes within the tightly package chromatin regions are often silenced.

The scientists used a new approach called proteomics, which examines proteins in a large scale, to gain new insight into the chromatin structure and function in rice. They identified a total of 344 unique proteins associated with chromatin and found a large number of histone variants in rice.

The researchers also determined that chromatin modification genes control the endosperm sizes and grain quality in rice. These findings suggest that manipulating chromatin modification genes may be an effective approach for the improvement of crop yield and quality. Future studies may also clarify how genes are expressed and how these genes control plant functions.