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
[www.isaaa.org] 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.





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