Abstract
BackgroundEven though the process of potato tuber starch biosynthesis is well understood, mechanisms regulating biosynthesis are still unclear. Transcriptome analysis provides valuable information as to how genes are regulated. Therefore, this work aimed at investigating transcriptional regulation of starch biosynthetic genes in leaves and tubers of potato plants under various conditions. More specifically we looked at gene expression diurnally in leaves and tubers, during tuber induction and in tubers growing at different velocities. To determine velocity of potato tuber growth a new method based on X-ray Computed Tomography (X-ray CT) was established.ResultsComparative transcriptome analysis between leaves and tubers revealed striking similarities with the same genes being differentially expressed in both tissues. In tubers, oscillation of granule bound starch synthase (GBSS) expression) was observed which could be linked to sucrose supply from source leaves. X-ray CT was used to determine time-dependent changes in tuber volume and the growth velocity was calculated. Although there is not a linear correlation between growth velocity and expression of starch biosynthetic genes, there are significant differences between growing and non-growing tubers. Co-expression analysis was used to identify transcription factors positively correlating with starch biosynthetic genes possibly regulating starch biosynthesis.ConclusionMost starch biosynthetic enzymes are encoded by gene families. Co-expression analysis revealed that the same members of these gene families are co-regulated in leaves and tubers. This suggests that regulation of transitory and storage starch biosynthesis in leaves and tubers, respectively, is surprisingly similar. X-ray CT can be used to monitor growth and development of belowground organs and allows to link tuber growth to changes in gene expression. Comparative transcriptome analysis provides a useful tool to identify transcription factors possibly involved in the regulation of starch biosynthesis.
Highlights
Even though the process of potato tuber starch biosynthesis is well understood, mechanisms regulating biosynthesis are still unclear
Amylose is essentially a linear polymer of glucose units linked with alpha (1,4) bonds whilst amylopectin has a higher percentage of branched alpha (1,6) bonds
Glucose 1-phosphate, along with ATP serves as substrate for ADP-glucose production by ADP-glucose pyrophosphorylase (AGPase), which is the first reaction committed to starch biosynthesis
Summary
Even though the process of potato tuber starch biosynthesis is well understood, mechanisms regulating biosynthesis are still unclear. This work aimed at investigating transcriptional regulation of starch biosynthetic genes in leaves and tubers of potato plants under various conditions. Starch is the most important carbohydrate source to the human diet, but has major industrial applications. It consists of two major fractions, amylose and amylopectin. In potato starch is either accumulated transiently in leaves or as storage starch in tubers. In leaves starch is synthesised in the chloroplast from triose-phosphates produced during photosynthesis. ADP-glucose is the glycosyl donor for the various starch synthases forming linear glucans which are subsequently branched by branching enzymes to produce starch
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
