Beyond the Green Revolution: Improving crop productivity and sustainability by modulating plant growth-metabolic coordination

Abstract

Rice is one of the most important staple food for over half the world's population. New evidence from the Food and Agriculture Organization shows that the number of hungry people in the world is growing, reaching more than 690 million in 2020. It is an urgent task to increase crop production to feed the people suffering from chronic hunger in the world. The Green Revolution of the 1960s boosted cereal yields through widespread adoption of semi-dwarf varieties and extensive use of inorganic fertilizers ( Khush, 2001 Khush G. Green revolution: the way forward. Nat. Rev. Genet. 2001; 2: 815-822 Google Scholar ). Today, the most productive Green Revolution varieties (GRVs) of rice and wheat in the world retain semi-dwarf phenotypes, which have several advantages over tall traditional varieties: (1) they have a lower center of gravity of the plant body, which decreases the risk of lodging and allows farmers to apply excessive fertilizers to obtain high yield; (2) they have an increased harvest index, which enables plants to allocate more energy and resources to seed production; (3) they exhibit an increased tillering, which makes it possible to increase grain yield per unit land area through increasing plant density ( Liu et al., 2022 Liu Q. Wu K. Song W. Zhong N. Wu Y. Fu X. Improving crop nitrogen use efficiency toward sustainable green revolution. Annu. Rev. Plant Biol. 2022; 73https://doi.org/10.1146/annurev-arplant-070121-015752 Google Scholar ). Although the Green Revolution is arguably one of humanity's greatest achievements, the growth-inhibitory mechanisms via which dwarfing alleles actually work remained unknown for a long time. This began to change with the release of the rice genome sequence and molecular discovery of semi-dwarf mutations ( Peng et al., 1999 Peng J. Richards D.E. Hartley N.M. Murphy G.P. Devos K.M. Flintham J.E. Beales J. Fish L.J. Worland A.J. Pelica F. et al. “Green revolution” genes encode mutant gibberellin response modulators. Nature. 1999; 400: 256-261 Google Scholar ; Sasaki et al., 2002 Sasaki A. Ashikari M. Ueguchi-Tanaka M. Itoh H. Nishimura A. Swapan D. Ishiyama K. Saito T. Kobayashi M. Khush G.S. et al. Green revolution: a mutant gibberellin-synthesis gene in rice. Nature. 2002; 416: 701-702 Google Scholar ).