Transcriptional expression of seven key genes involved in steroidal glycoalkaloid biosynthesis in potato microtubers

Abstract

Red light (10–12 lx) has been shown to induce the accumulation of steroidal glycoalkaloids (SGA) in potato (Solanum tuberosum) tubers. This study was to analyse the impact of genotypes, red light illumination and duration of incubation on SGA biosynthesis at the transcriptional level. The microtubers of wild species S. chacoense and cultivated potato varieties Shepody, Favorita, Longshu-3 and Zhuangshu-3 were tested. After 24 h incubation in the dark, the genes coding for hydroxymethylglutaryl coenzyme A reductase (hmg1, hmg2) and squalene synthase (pss1) remained relatively stable in S. chacoense and Longshu-3. The gene coding for vetispiradiene synthase (pvs1) was significantly induced in Favorita and Longshu-3. The expressions of sgt1 (solanidine galactosyl transferase) and sgt3 (rhamnosyltransferase) were induced in all tested varieties except S. chacoense. The transcript abundance of hmg1, hmg2, sgt1 and sgt3 was increased with red light illumination and incubation duration, but pvs1 was decreased. The results imply a feedback regulation system at the transcriptional level in SGA biosynthesis during red light illumination.