Zhao, Y.

Stomata are the pores on plant surface, and these tiny pores are responsible for the flow of gas between plants and atmosphere. Increased stomatal density through genetical manipulation has been shown to accompany improved leaf photosynthetic rate. However, whether increasing stomatal density by genetical manipulation could improve plant biomass remains unknown. The Arabidopsis transgenic lines with increased stomatal density were acquired through over-expressing a gene (the homologs of STOMAGEN, FSTOMAGEN, the homologs in Flaveria). The biomass of Arabidopsis transgenic lines with stomatal density raised to intermediate-level increased. Compared to the lines with lowest stomatal density, the biomass of the transgenic lines with exorbitant stomatal density showed no difference, even decrease. There was a positive correlation between biomass and water content, supporting that biomass is affected by water content, and excess stomata do not benefit the improvement of biomass due to the excessive loss of water. During the earlier stage of growth, the leaf growth rate and leaf area of the lines with increased stomatal density was faster and larger respectively, which was in agreement with the notion that more stomata indicated faster CO2 assimilation and then faster accumulation of biomass. Results indicated that finely tuning stomatal density could improve Arabidopsis biomass by genetically manipulating FSTOMAGEN. The function of STOMAGEN family is extremely conserved in evolution, thus it is promising that this genetically modified strategy to increase biomass could be applied in the other species, and furthermore benefit the reduction of the concentration of atmosphere CO2 and the production.