Ricinus communis is an important oilseed crop worldwide and is also considered one of the best potential plants for salt-affected soil improvement in northeast China. However, little is known about photosynthesis and carbohydrate metabolism in this plant, nor the distribution of carbohydrates in cotyledons and roots under salinity stress.• In the present study, seedling growth, gas exchange parameters (P N , E, g s and C i ), carbohydrate (fructose, sucrose, glucose, soluble sugar and starch) metabolism and related enzymes and genes were measured in Ricinus plants.• Under salt stress, P N of cotyledons decreased significantly (P < 0.05), resulting in weak photosynthetic capacity. Furthermore, salt stress increased sucrose and glucose content in cotyledons, but decreased soluble sugar and starch content. However, sucrose increased and starch decreased in roots. This may be correlated with the increasing sugar metabolism under salinity, including notable changes in sugar-related enzyme activities (SPS, SuSy, α-amylase and β-amylase) and gene expression of RcINV, RcSUS, RcAmY, RcBAM and RcGBE1.• The results suggest that salinity reduces photosynthesis of cotyledons, alters carbohydrate allocation between cotyledons and roots and also promotes starch utilization in cotyledons and starch biosynthesis in roots, leading to a functional imbalance between cotyledons and roots. Together, these findings provide insights into the crucial role of sugar metabolism in improving salt-tolerance of Ricinus during the early seedling growth stage.

Phosphoglucomutases (PGM) (5.4.2.2.) belong to the Phosphohexomutases superfamily and are highly specific in catalyzing the interconversion of Glc-1-P to Glc-6-P. In this study, we characterize the expression and activity of two cytosolic PGMs (cPGM2 and cPGM3) stigmas of ornamental kale during flower development. In stigmas, cPGM expression and activity showed a gradual increase during stigma development with the highest activity around the time of anthesis. Blocking of cPGM activity in the stigmas using a known inhibitor, resulted in breakdown of self-incompatibility in immature S3 and S4 stigmas, but had no effect on the fully mature S5 stigmas. It is likely that cPGMs are required for accumulation of factors necessary for SI response in mature stigmas.