Role Of FUGU5 /AVP1 In Post-germinative Growth And Organ-size Control

Abstract

In leaves of Arabidopsis thaliana, excessive cell enlargement is often triggered by decreased cell proliferation activity. This has suggested that cell proliferation and cell expansion are fundamentally coordinated for proper organogenesis. Our recent analyses of the compensation exhibiting mutant fugu5 has revealed that compensation was totally cancelled when fugu5 was grown on MS medium. We found that sucrose was necessary and sufficient for fugu5 phenotype recovery. Furthermore, compensation in fugu5 occurred only in cotyledons and the first pair of rosette leaves, but not in rosette leaves of higher nodes. Map-based cloning of FUGU5 gene revealed that it is AVP1, which encodes for a vacuolar type H⁺-pyrophosphatase. Pyrophosphatase activity is totally lost in three fugu5 mutant alleles. Interestingly, the transition of protein bodies to central vacuole was significantly delayed in fugu5 cotyledons. Taken together, these results indicate that FUGU5 plays particularly an important role during early stages of seedling development.