Abstract: This study aims to examine the effects of sucrose non-fermenting-1-related protein kinase 1（SnRK1）from Malus hupenhensis Rehd.（Pingyitiancha）on seed germination and seedling growth in tomatoes. The germination and growth of two tomato lines overexpressing Malus hupenhensis SnRK1 （MhSnRK1），O-7 and O-9，as well as their wild-type counterpart（WT），were monitored in six different mediums. The results showed that，the germination rates of the three tomato lines were all 100% in MS medium but declined to varying degrees in trehalose medium，with WT showing the lowest germination efficiency（WT，23.3%；O-7，70.3%；O-9，67.7%）. Meanwhile，the SnRK1 activities of O-7 and O-9 cultivated in MS were 12.1% and 2.3% higher，respectively，compared to that of WT. The addition of trehalose led to a 41.5% reduction in the activity of SnRK1 in WT，35.5% in O-7 and 27.5% in O-9. Fourteen days after sowing，trehalose was found to significantly suppress the growth of taproot and hypocotyl in all three tomato lines，with the inhibitory effect more pronounced on WT than on the two transgenic tomato lines. The introduction of 0.3 mg · g-1 IAA was shown to mitigate the inhibitory effect of trehalose on hypocotyl elongation in WT. As a result，in MS medium，WT displayed flatter，flesher and larger cotyledon，as well as better-developed true leaf，compared to O-7 and O-9 at day 30 after sowing. And the leaf chlorophyll content of WT was significantly higher than that of O-7 and O-9. These results showed that overexpressing MhSnRK1 in tomato could regulate the seed germination and seedling growth. In a certain range，the higher SnRK1 activity promoted the seed germination，inhibited the taproots and hypocotyls of seedling elongating，while the lower SnRK1 activity is more conducive to the growth and development of the seedlings.

Key words: Malus hupenhensis, MhSnRK1, tomato, SnRK1 activity, seed germination rate, hypocotyl