Meristems such as the shoot apical meristem and flower meristem (FM) act as
a reservoir of stem cells. In rice (Oryza sativa), the FLORAL ORGAN NUMBER2
(FON2) gene is involved in meristem maintenance. In fon2 mutants, the
numbers of floral organs are increased due to an enlargement of the FM. To
identify new factors regulating meristem maintenance in rice, researchers
from the University of Tokyo in Japan studied the 2B-424 rice line, a fon2
mutant with increased pistil number.

Researchers found that the 2B-424 line had a complete loss-of-function
mutation in OsMADS3, a gene that is known to be involved in stamen
specification. Using CRISPR-Cas9 technology, the team disrupted OsMADS3 in
the fon2 mutant, causing a flower phenotype similar to that of 2B-424. This
confirms that the gene responsible for enhancement of fon2 was OsMADS3.

Morphological analysis revealed that the fon2 and osmads3 mutations both
simultaneously affected pistil development. These findings suggest that
OsMADS3 is also involved in FM activity in early flower development.

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