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Effect of wet storage conditions on potato tuber transcriptome, phytohormones and growth
- Peivastegan, Bahram, Hadizadeh, Iman, Nykyri, Johanna, Nielsen, Kåre Lehmann, Somervuo, Panu, Sipari, Nina, Tran, Cuong, Pirhonen, Minna
- BMC plant biology 2019 v.19 no.1 pp. 262
- Solanum tuberosum, abiotic stress, abscisic acid, anaerobic conditions, biosynthesis, cell walls, chloroplasts, gene expression, gene expression regulation, genes, greenhouses, heat shock proteins, indole acetic acid, jasmonic acid, messenger RNA, microarray technology, oxygen, pathogens, potatoes, proteinase inhibitors, quantitative polymerase chain reaction, reactive oxygen species, reverse transcriptase polymerase chain reaction, root growth, roots, salicylic acid, secondary metabolites, seed germination, sequence analysis, stems, storage time, temperature, transcriptome, tubers
- BACKGROUND: Stored potato (Solanum tuberosum L.) tubers are sensitive to wet conditions that can cause rotting in long-term storage. To study the effect of water on the tuber surface during storage, microarray analysis, RNA-Seq profiling, qRT-PCR and phytohormone measurements were performed to study gene expression and hormone content in wet tubers incubated at two temperatures: 4 °C and 15 °C. The growth of the plants was also observed in a greenhouse after the incubation of tubers in wet conditions. RESULTS: Wet conditions induced a low-oxygen response, suggesting reduced oxygen availability in wet tubers at both temperatures when compared to that in the corresponding dry samples. Wet conditions induced genes coding for heat shock proteins, as well as proteins involved in fermentative energy production and defense against reactive oxygen species (ROS), which are transcripts that have been previously associated with low-oxygen stress in hypoxic or anoxic conditions. Wet treatment also induced senescence-related gene expression and genes involved in cell wall loosening, but downregulated genes encoding protease inhibitors and proteins involved in chloroplast functions and in the biosynthesis of secondary metabolites. Many genes involved in the production of phytohormones and signaling were also affected by wet conditions, suggesting altered regulation of growth by wet conditions. Hormone measurements after incubation showed increased salicylic acid (SA), abscisic acid (ABA) and auxin (IAA) concentrations as well as reduced production of jasmonate 12-oxo-phytodienoic acid (OPDA) in wet tubers. After incubation in wet conditions, the tubers produced fewer stems and more roots compared to controls incubated in dry conditions. CONCLUSIONS: In wet conditions, tubers invest in ROS protection and defense against the abiotic stress caused by reduced oxygen due to excessive water. Changes in ABA, SA and IAA that are antagonistic to jasmonates affect growth and defenses, causing induction of root growth and rendering tubers susceptible to necrotrophic pathogens. Water on the tuber surface may function as a signal for growth, similar to germination of seeds.