SP6A (Self-Pruning) Gene in Potato (Solanum tuberosum L.): Structural Features and Expression Patterns

Abstract

StSP6A gene codes for a long distance travelling RNA which acts as a mobile signal. It is expressed in both reproductive and vegetative organs in potato and other plants. It works as mobile signal which originates in leaf under short day conditions and further gets transported to the underground stolon tips to initiate tuberization. It is an important member of Self Pruning (SP) family of tomato (Solanum lycopersicum) and homologous to FT gene from Arabidopsis thaliana and CEN gene from Antirrhinum. Considerable progress has been made on StSP6A gene function associated with various stages of growth and development particularly in the Solanaceae family members. This study focused mainly on StSP6A gene since as this gene function gained importance significantly for its involvement in the process of tuberization in potato. Some in silico approaches were adopted to analyze the following aspects: sequence identity, sequence analysis, multiple sequence alignment, searching protein motifs, and 3-D modeling along with some other attributes. Most of the data are important as they were not reported earlier. Some experiments were also carried out to know the expression patterns of SP6A gene in different potato organs. Total RNA was isolated from field grown potato namely leaf, root, petiole, flower, small tuber, large tuber and tuberizing stolon. First, reverse transcription (RT) was carried out using organ specific individual total RNA samples and SP6A cDNA-specific oligonucleotide primer(s). Subsequently, the RT products were employed to carry out PCR. The size of the amplicon was~ 400 bp. Similar amplicon was also found using potato genomic DNA as template indicating the absence of intron sequences in the gene of study. RT-PCR data clearly indicated the presence of SP6A transcripts in the leaf and tuberizing stolon. However, the transcript could hardly be detected in other potato organs. In the context of Indian potato cultivars, this study would be useful particularly for studying the complex tuberization process.