The NANA Gene Regulates Division and Elongation of Stem Cells in Arabidopsis thaliana (L.) Heynh.

The dominant nana (na) mutation mapped to the top arm of Arabidopsis thalianachromosome 1 blocks cell proliferation in apical meristem (AM) of the inflorescence at its early development and suppresses the subsequent elongation by internode cells. Thenamutation reduces the sensitivity of cells of the inflorescence to gibberellin (GA) and paclobutrazole (PBZ) and prevents dormant and immature seeds from restoring the germinating ability in response to exogenous GA. On the other hand, exogenous GA and PBZ affects the onset of flowering, hypocotyl length, and leaf color; i.e., thena mutant displays an alteration of only several, rather than all, GA-dependent processes. Based on the results obtained, the product of the NA gene was assumed to play a role in the negative regulation of GA signaling and to act later than the products of the known GAI and SPY genes.