FZP Controls Sterile Lemma in Rice Grains

In grasses, the spikelet is a unique inflorescence structure that directly determines grain yield. Despite a great number of studies, the mechanisms behind spikelet development are not fully understood. Deyong Ren from China National Rice Research Institute studied the FZP gene and how it influences grain size and sterile lemma identity in rice (Oryza sativa).

Mutation of FZP causes smaller grains and degenerated sterile lemmas. Analysis revealed that the small grains from the fzp-12 mutant were caused by a reduction in cell number and size in the hulls. Interestingly, the sterile lemma transformed into a rudimentary glume in the mutants. Meanwhile, the sterile lemma transformed into a lemma in FZP- overexpressing plants.

To confirm their hypotheses, the team used CRISPR-Cas9 gene editing to modify the FZP gene, generating rice lines with similar phenotype to the fzp mutants. Further analysis also revealed that FZP may also be involved in regulation of the downstream genes.

These results confirmed that FZP plays a role in the regulation of grain size. This study also provides evidence that the lemma, rudimentary glume, and sterile lemma are homologous organs.

For more information, read the article in Journal of Experimental Botany.