RSS1, a factor required for the maintenance of meristem activity under salinity, interacts with protein phosphatase 1

Abstract

Post-embryonic growth in plants largely depends on activity of meristems in shoots and roots. For proper tissue organisation, it is essential that cell division be coordinated with cell differentiation and that it be in synchrony with the cycles of neighbouring cells. However, it is unknown how the proliferative activities of the meristems and coordination between cell division and differentiation are maintained under stressful conditions. We have shown that a novel rice protein RSS1 contributes to the vigour of meristematic cells and the viability of the entire plant under salinity conditions. This effect is achieved by maintenance of the G1-S transition and the activity of the phytohormone cytokinin in shoots. Recently, we found that RSS1 stability is controlled by cell cycle phases, and that RSS1 interacts with protein phosphatase 1 (PP1). PP1 is known to activate Retinoblastoma protein, a regulator of G1-S transition. A possible role of RSS1 to regulate cell cycle under stress conditions will be discussed.