Recently, CNRRI scientists cloned a novel regulatory factor involved in spikelet development, lacking rudimentary glume 1 (lrg1) and revealed the mechanism by which lrg1 regulates spikelet organ identity and grain size.

In this study, a new recessive rice mutant lrg1 was derived using ethyl methanesulfonate (EMS). The lrg1 mutant formed elongated sterile lemmas and rudimentary glumes, which were transformed into lemma-like organs with the lemma identity. The grains of the lrg1 mutant were shorter and wider compared with those of the wild type. It was shown that LRG1 was the first marker gene in regulating the development of rudimentary glume and was specially expressed in the rudimentary glume. LRG1 encodes a ZOS4-06-C2H2 zinc-finger protein, which perform its inhibitory role for the co-expression of floral organ genes (DL, OsMADS1, and OsMADS6) by interacting with TPRs, affecting the formation and development of the rudimentary glumes and sterile lemmas. It is revealed that the rudimentary glume, the sterile lemma, and the lemma are homologous organs, which strongly supports“three-floret spikelets” hypothesis. Besides, LRG1 is found to be an important regulator of grain size. Findings show that LRG1 can serve as a novel genetic resource for molecular design breeding of good quality and high yield rice.

This work was supported by the Zhejiang natural science foundation (LY18C130007), the National Natural Science Foundation of China (91735304), the Central Public-interest Scientific Institution Basal Research Fund of China National Rice Research Institute (2017RG001-4), the National Science and Technology Major Project (2016ZX08009003-003-008). Results have been published online in Science Bulletin entitled “The C2H2 zinc-finger protein LACKING RUDIMENTARY GLUME 1 regulates spikelet development in rice”.

More details can be found in the link below:

https://www.sciencedirect.com/science/article/pii/S2095927320300438