During the Green Revolution, high-yielding dwarfed Green Revolution Varieties (GRVs) were developed. These varieties are still widespread today and have increased fertilizer use.
The numbers of grain-bearing branches (‘tillers') per plant are increased in GRVs, further enhanced by increased nitrogen fertilizer use to boost grain yield. However, fertilizers are costly to farmers and cause extensive environmental damage. The study led by Professor Xiangdong Fu from the Chinese Academy of Sciences' Institute of Genetics and Developmental Biology, and Professor Nicholas Harberd from the Department of Plant Sciences at the University of Oxford has for the first time discovered a gene that can help reach that goal.
The study has identified a rice gene that responds to nitrogen, increasing the accumulation in plant cells of a protein called NGR5. Nitrogen-stimulated NGR5 accumulation then alters the structure of genes that inhibit tiller growth, switching them off and thus increasing the numbers of yield-enhancing tillers. Increased tiller number is also caused by DELLA, another branching-promoting protein, whose accumulation is reduced by the hormone gibberellin (GA). The study found that GA also reduces NGR5 accumulation, and that tiller growth is the product of complex interactions between the NGR5 and DELLA proteins.
For more details, read the article at the University of Oxford News & Events.