A major study of the genetic profile of more than 10,000 rice variants has revealed clues why hybrid rice has higher performance in certain traits than its parent varieties, scientists from China reported.
The study was carried out under the direction of Professors Han Bin and Huang Xuehui of the Institute of Plant Physiology and Ecology at the Shanghai Institutes for Biological Sciences, and published in the journal Nature.
The researchers were investigating the phenomenon of heterosis, which is the increase in characteristics such as size, growth rate, fertility, and yield of a hybrid variety over those of its parents.
Heterosis is a well-known phenomenon and offers an important strategy for crop breeding. It is considered one of the most efficient ways to increase grain yield in many crops, including rice, maize and sorghum, but the genetic cause of heterosis has until now largely been unknown, the researchers explained.
The study team analyzed over 10,000 hybrid rice lines produced from 17 elite rice lines, mapping for yield-related traits and evaluating heterotic effects. From the genomic and phenomic data, the researchers classified modern rice varieties into three major types, reflecting the major breeding systems.
Within each of these groups, they identified a few regions in genes and some specific gene alleles from female parents linked to heterosis effects for improved yields, but found that these differed across the three groups.
Overall, the study authors found that the hybrids that gave overall improved yields resulted from an optimal combination of multiple yield-related components identified in the parent varieties through the genomic profiling.
“This knowledge may be useful for crop improvement programs,” the researchers said in their conclusion.