Growing Conditions and Varietal Ecologies Differently Regulates the Growth-regulating-factor (GRFs) Gene Family in Rice

Growth-regulating factors (GRFs) are crucial in rice for controlling plant growth and development. Among the rice cultivation practices, aerobic methods are water efficient but result in significant yield reduction relative to non- aerobic cultivation. Therefore, mechanistic insights into aerobic rice cultivation are important for improving the aerobic performance of rice. Objectives This study aimed to examine the evolution of GRFs in different rice species, analyse the phenotypic differences between aerobic and non-aerobic conditions in three rice varieties, and assess the expression of GRFs in these varieties under both aerobic and non-aerobic conditions.

This study comprehensively examined the GRFs gene family in 11 rice species (Oryza barthii, Oryza brachyantha, Oryza glaberrima, Oryza glumipatula, Oryza sativa subsp. indica, Oryza longistaminata, Oryza meridionalis, Oryza nivara, Oryza punctata, Oryza rufipogon, Oryza sativa subsp. japonica) focusing on phylogenetic analysis. Additionally, the expression patterns of 12 GRFs were investigated in three distinct genotypes of O. sativa subsp. indica rice, under both non-aerobic and aerobic conditions.

 Results:

 Three major phylogenetic clades were formed based on conserved motifs in the 123 GRFs proteins in eleven rice species. Further, novel motifs were identified especially in O. longistaminata indicative of the species level evolutionary differences in rice. Among the trait performance, the number of tillers was reduced by ~ 36% under aerobic conditions, but the reduction was found to be less in CR Dhan 201, an aerobic variety. Besides, three GRFs namely GRF3, GRF4, and GRF7 were found to be distinct in expression between aerobic and non-aerobic conditions.

Conclusion:

 Three GRF genes namely GRF3, GRF4, and GRF7 could be associated with the aerobic adaptation in rice