Tuber transcriptome profiling of eight potato cultivars with different cold-induced sweetening responses to cold storage

Citation

Tai, H.H., Lagüe, M., Thomson, S., Aurousseau, F., Neilson, J., Murphy, A., Bizimungu, B., Davidson, C., Deveaux, V., Bègue, Y., Wang, H.Y., Xiong, X., Jacobs, J.M.E. (2020). Tuber transcriptome profiling of eight potato cultivars with different cold-induced sweetening responses to cold storage. Plant Physiology and Biochemistry, [online] 146 163-176. http://dx.doi.org/10.1016/j.plaphy.2019.11.001

Plain language summary

Potato tubers need to be stored for several months prior to processing into French fries and chips. Storage at low temperatures of 2-4 °C is used to suppresses diseases and prevent sprouting of tubers. The problem is that this low temperature is a cold stress for tubers. The response to cold stress is genetically variable. Glucose is produced in some potato clones as a protective molecule. Glucose can stabilize cells upon chilling. Also increasing concentrations of glucose in plant cells has the effect of lowering the freezing temperature, which prevents formation of cell-damaging ice crystals. Potato cultivars with genetic differences in the production of glucose in tubers under cold storage, which is also referred to as cold-induced sweetening, were compared. The study examined genes involved in cold response in potato tubers using analysis of the gene expression. Gene expression is the process where genes required for function are copied into transcripts called mRNA. Analysis of the mRNA provides an identification of the genes expressed and a quantification of amount of expression. The study demonstrated that cultivars that have low glucose under cold storage express genes involved in cell division, whereas cultivars with high glucose expressed abiotic stress response genes. The results suggest that low glucose producing clones may have reduced abiotic stress response under cold temperatures. The findings of the study will be used to develop markers and indicators for selecting potato cultivars with low glucose production under cold storage. The study also identified potato germplasm with potential for use in breeding of cultivars for use in fry processing.

Abstract

Tubers are vegetative reproduction organs formed from underground extensions of the plant stem. Potato tubers are harvested and stored for months. Storage under cold temperatures of 2–4 °C is advantageous for supressing sprouting and diseases. However, development of reducing sugars can occur with cold storage through a process called cold-induced sweetening (CIS). CIS is undesirable as it leads to darkened color with fry processing. The purpose of the current study was to find differences in biological responses in eight cultivars with variation in CIS resistance. Transcriptome sequencing was done on tubers before and after cold storage and three approaches were taken for gene expression analysis: 1. Gene expression correlated with end-point glucose after cold storage, 2. Gene expression correlated with increased glucose after cold storage (after-before), and 3. Differential gene expression before and after cold storage. Cultivars with high CIS resistance (low glucose after cold) were found to increase expression of an invertase inhibitor gene and genes involved in DNA replication and repair after cold storage. The cultivars with low CIS resistance (high glucose after cold) showed increased expression of genes involved in abiotic stress response, gene expression, protein turnover and the mitochondria. There was a small number of genes with similar expression patterns for all cultivars including genes involved in cell wall strengthening and phospholipases. It is proposed that the pattern of gene expression is related to chilling-induced DNA damage repair and cold acclimation and that genetic variation in these processes are related to CIS.

Publication date

2020-01-01