Abstract: MhSnRK1-overexpressing tomato（O-7）and wild type tomato were used to investigate the function of MhSnRK1 on carbohydrate metabolism. The results showed that ten genes in photosynthesis pathway were differentially expressed between MhSnRK1-overexpressing line and wild type，among which seven genes were up-regulated in MhSnRK1-overexpressing line through digital gene expression（DGE）analysis. Compared with wild type tomato，the average photosynthetic rates increased by 20.3% in mature leaves of MhSnRK1-overexpressing tomato. SnRK1 activities in young and mature leaves increased respectively by 20.6% and 25.0% of MhSnRK1-overexpressing tomato. The soluble sugar contents in young leaves and in mature leaves increased by 57.7% and 27.0% respectively. In young leaves of MhSnRK1-overexpressing tomato SnRK1 activity was obviously higher than that in mature leaves. Thestarch contents were nearly doubled in young leaves of MhSnRK1-overexpressing tomato，while there was no obvious difference in starch content between these leaves of the wild type. After trehalose treatments，the photosynthetic rates decreased in mature leaves of MhSnRK1-overexpressing and wild type tomato and wild type tomato decreased more. SnRK1 activities in young and mature leaves of MhSnRK1-over- expressing and wild type tomato both decreased，while MhSnRK1-overexpressing line was still higher than wild type tomato.

Key words: Malus hupehensis Rehd. var. pingyiensis Jiang, SnRK1, tomato, digital gene expression-tag profiling, soluble sugar, starch, photosynthetic rate