Nutrients translocation & plant growth in tissue culture

In conventional plant micropropagation exogenous sucrose is generally taken up by plants from the medium. Any treatment that improves sucrose assimilation or translocation might promote plant growth and micropropagation efficiency. Transpiration is widely believed to be at a very low level in vitro and subsequently the water flow and nutrient translocation are supposed to be marginal. We investigated the relation between growth and sucrose translocation on the one hand and leaf transpiration on the other hand in vitro. It was found that both transpiration, including the transpiration roles of surface cuticle and of stomatal activity, and sucrose assimilation attributed by water transport contributed to biomass accumulation in plants as the main reason for growth. It was also examined the role of sucrose transporter genes in the process of exogenous sucrose translocation in roots. The results demonstrated the importance of SWEET11 and SWEET12 genes in exogenous sucrose assimilation and translocation in vitro. In addition we emphasized the contribution of aquaporin plasma membrane intrinsic proteins PIP1 to the growth of in vitro plants through investigating physiological characteristics in miRNA-induced-PIP1s-silenced plants. As a woody plant Malus domestica ‘Gala’ was used to test whether increased transpiration generally can lead to improved plantlet growth in shoot culture and to demonstrate the relationship between transpiration, stomatal and cuticular transpiration, and plantlet growth in vitro. A follow up of this research should focus on plantlet growth promotion by cuticle manipulation and sucrose assimilation and translocation via fresh cut section.