Analysis of genes differentially expressed during potato tuber life cycle and isolation of their promoter regions

Abstract

The potato tuber life cycle involves several developmental stages including tuberisation, tuber growth, dormancy and sprouting. Gene expression during the potato tuber life cycle has been monitored using a RNA fingerprinting technique termed cDNA-AFLP. The expression profile of the nearly 2000 transcript derived fragments (TDFs) was analysed and general conclusions concerning the different stages of tuber life cycle and tissue specificity were drawn. Comparison of 116 TDFs isolated and sequenced to the NCBI databases indicated that most of the genes expressed during tuber life cycle are involved in defence, stress, storage and signal transduction pathways. In order to identify time and tissue specific regulatory elements, the TDFs were further screened for their time and tissue specific expression and the putative promoters corresponding to the twelve differentially expressed TDFs were isolated. Comparison of the 12 upstream sequences to all described cis-acting elements resulted in the identification of 12 know cis-acting elements: two general cis-elements, one enhancer and nine specific boxes. These specific cis-elements have been characterised in other plant species and they respond to light, sugars and hormones such as gibberellins, auxins and abscisic acid (ABA). All these environmental factors play an important role during the potato tuber life cycle.