During the process of gas exchange, the plant transpires water vapor into the surrounding atmosphere and CO 2 for photosynthesis enters the plant. Stomata are the gates that allow the exchange of gases between the atmosphere and the inner tissues of the plant. We suggest that the stomata of young green citrus fruits, but not mature yellow fruits, respond to sugar levels via HXK and that fruit stomata are important for proper seed development. Seeds of the GCHXK plants were smaller and germinated more slowly than the WT seeds. Toward fruit maturation, fruit stomata are plugged and stop functioning, which explains why WT and GCHXK mature yellow fruits exhibited similar water loss. The transpiration of young green GCHXK citrus fruits was significantly reduced, indicating that their stomata respond to sugar similar to leaf stomata. Those plants are referred to as GCHXK plants. The activity and response of citrus fruit stomata to sugar-sensing by HXK was examined using plants that express HXK under the KST1 promoter. It has previously been shown that hexokinase (HXK) mediates sugar-sensing in leaf guard cells and stimulates stomatal closure. Stomata are found on the style, sepal, and anther of the closed flower and on ovules from the stage of anthesis. The temporal formation and spatial distribution of stomata on the surface of citrus floral organs and, specifically, on the ovule from which the fruit develops, were analyzed using citrus plants that express green fluorescent protein (GFP) under the guard cell-specific KST1 promoter.

The night of tal bauer