Keywords: 
• banana /
• leaf senescence /
• real-time PCR /
• invertase gene /
• senescence associated gene

Abstract: Leaf premature senescence phenomenon is proved to have obvious effect on the quality and yield of banana fruit. So,unveiling of the mechanism of leaf senescence would have a profound significance on the theory and practice for improving the quantity and quality of banana. The third leaves were detached and collected from tissue cultured banana plants of 3 months old. They were treated in light,dark,6-BA + light,or 6-BA + dark with 3 replications and collected at different hours after treatment for RNA extraction. Expressions of genes related to invertase and leaf senescence in the leaves treated were determined by using the real-time fluorescence quantitative PCR approach（ RT-PCR）,and their changes were analyzed in leaf senescence.. In the darkness treatment to induce senescence of the detached banana leaves the sucrose concentration declined,leading to sucrose starvation and high expression of senescence-associated genes（ SAG） after the cell wall invertase genes（ INCWs） were highly expressed. This experiment gives a molecular support to the conclusion of the leaf senescence initiation reported at physiological and biochemical levels: that leaves were induced by sucrose starvation to start their senescence process.