Effects Of SnRK1 Protein Kinase On The Carbon Metabolism And Growth Of Strawberry And Tomato Plants

The SNF1-related kinase(SnRK1),with SnRK2 and SnRK3 belongs to snf1-related protein kinases superfamily(SnRKs),plays central role in regulating carbon and nitrogen metabolism and energy balance in plant.In this study,based on strawberry genome database GDR,the sequences of SnRK1 family genes were identified in strawberry.By using q RTPCR,we have comprehensive studied the expression characteristic of FaSnRKs in various strawberry tissues and responsing to SA.By spraying and pouring SA,we have studied the effects of SA on SnRK1 activity,plant growth and carbon metabolism.Additionally,PpSnRK1?-overexpressing tomato(T2-3)and wild type tomato were used to study the effects of SnRK1 on the growth of tomato plants under nutrient stress.This study provides theoretical basis on taking SnRK1 as the target to regulate the ftuit tree growth.The main results are shown as follows:1.In Fragaria × ananassa genome,there are 5 members in strawberry SnRK1 gene family,named FaSnRK1?(FANhyb_rscf00000747.1.g00007.1),FaSnRK1?(FANhyb_rscf00002795.1.g00001.1),FaSnRK1?(FANhyb_rscf00000016.1.g00029.1),FaSn RK1??1(FANhyb_rscf00001741.1.g00001.1),FaSnRK1??2(FANhyb_rscf00000139.1.g00009.1).The fragment of FaSnRK1 s is1601bp,768 bp,1290bp,1331 bp and1596bp,respectively.Compared with the homologous genes of other species we found that there is higher homology between FaSnRK1 s and the other species.Phylogenetic tree analysis showed that the cultivation of strawberry(Fragaria x ananassa)SnRK1 amino acid sequence and the wild strawberry(Fragaria vesca)homologous relationship very close.2.Through real-time PCR we found that FaSnRK1 s expressed in roots,stems,leaves,flowers,and fruit of strawberry,the level of FaSnRK1? and FaSnRK1??1 is highest in leaves;the level of FaSnRK1?,FaSnRK1? and FaSnRK1??2 is highest in flowers,FaSnRK1 s has weaker expression in fruit.3.The expression of FaSnRK1 s was regulated by salicylic acid in various strawberry tissues,and the response was tissue-dependent.The expression within 0.5~ 1 h reached the highest level in roots,and within 1~ 2 h reached the highest level in leaves,then dropped,until stable at the initial level.This indicate that the stimulus of SA on FaSnRK1 s expressions are short-term.Relatively high concentrations of SA treatted(including 80?M and 100?M)strawberry leaves and root system,the SnRK1 protein kinase activity is increased in a short period of time,but after 24 h the effect is not obvious.4.After treatment with salicylic acid,the photosynthetic rate of mature leaves increased,and the contents of soluble sugar and starch were increased significantl.Potted strawberry treatted with salicylic acid,the photosynthetic rate,soluble sugar and starch content were increased,and the plant growth was promoted.The results shows that salicylic acid can affect the plant growth through influence carbon metabolism.5.Compared with wild type tomato,SnRK1 activities in leaves and roots increased by 41.55% and 39.46% of PpSnRK1?-overexpressing tomato under nutrient stress.The average photosynthetic rates increased by 18.89% in mature leaves of T2-3 compared with WT.After 12 days under low nutrient stress,the transgenic lines overexpressing PpSnRK1? showed better antioxidant enzymes and root activity.The SOD/POD/CAT activities and root activity were increased 35.56% 8.85% 14.90% and 26.39% compared with WT.The content of N P in the leaf higher than wild type plants,while there were no obvious difference in the K content.In the roots,there were no significant difference in the N P content,while the content of K obviously higher than WT.In addition,more N was distributed to aboveground parts.These results above show that overexpressing PpSnRK1? can improve the photosynthetic rates and promote the absorption of nitrogen,and then delay the leaf senescence.