Effect of strigolactones on sugar metabolism and gene expression about sugar-metabolizing enzymes in tobacco axillary buds and its corresponding nodal leaves
Utilizing the tobacco cultivar'K3261(Nicotiana tabacum)as the experimental material,this inves-tigation sought to assess the impact of the strigolactones(SLs)analogue GR24 on sugar metabolism and the expression of enzyme-related genes in axillary buds and their corresponding nodal leaves after decapi-tation.The findings demonstrated that the application of exogenous GR24 significantly increased the su-crose content,as well as the activities of sucrose phosphate synthase(SPS)and invertase(INV)in the ax-illary buds located at the 3rd node position of tobacco.Conversely,it led to a notable reduction in sucrose content and the activity of sucrose synthase(SS)in axillary buds at the 1 st to 2nd node positions.Simulta-neously,GR24 had a decreasing effect on the levels of starch,fructose,and sucrose in the tobacco leaves,along with a significant reduction in the INV activity of leaves at the 1st to 2nd node positions.Conversely,there was an increase in the a-amylase activity of leaves at the 1st to 2nd node positions due to GR24 treatment.Further exploration through RNA-sequencing revealed that GR24 downregulated the expression of several genes,including AMY1.1 and AMY2(which encode a-amylase),SSa,SUS5,SUS6,SUS7(which encode SS),SPS4(which encodes SPS),and INVA(which encodes INV).On the other hand,the expression of BAM1b and BAM1(which encodes β-amylase),as well as cINV1 and CWINV(which encodes INV),was notably upregulated in response to GR24 treatment.These results suggested that SLs could influence the sugar metabolism of leaves at the corresponding nodes of axillary buds by affecting alterations in the ac-tivities of enzymes of sugar metabolism associated with the synthesis and breakdown of tobacco axillary buds,along with the regulation of genes that encode these enzymes.
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