Late embryogenesis-abundant (LEA) proteins are a large and highly diverse family believed to function in normal plant growth and development, and in protecting cells from abiotic stress. This study presents a characterisation of 74 Solanum tuberosum LEA (StLEA) proteins belonging to nine groups. StLEA genes have few introns (≤2) and are distributed on all chromosomes, occurring as gene clusters on chromosomes 1, 2, and 10. All four StASR (StLEA7 group) genes were concentrated on chromosome 4, suggesting their evolutionary conservation on one chromosome. Expression profiles of StLEA genes, in different tissues and in response to hormone and stress treatments, indicated that 71 StLEA genes had differential expression levels, of which 68 StLEA genes were differentially expressed in response to hormones and stress exposure in the potato. Continuous high expression of StASR-2, StLEA3-3, StDHN-3, StLEA2-29, and StLEA2-14 in different tissues indicated their contribution to plant development processes. StLEA2-14, StLEA2-31, StLEA3-3, StASR-1, and StDHN-1 were upregulated by six abiotic stresses, showing their tolerance to a wide spectrum of environmental stresses. Expression analysis of 17 selected StLEA genes in response to drought, salt, heavy metal, heat, and cold treatments by quantitative real-time polymerase chain reaction indicated that StLEA proteins may be involved in distinct signalling pathways. Taken together, StLEA3, StDHN, and StASR subgroup genes may be excellent resources for potato defence against environmental stresses. These results provide valuable information and robust candidate genes for future functional analysis aimed at improving the stress tolerance of the potato.

Potato is an important food crop and its production is susceptible to drought. Drought stress in crop growth is usually multiple- or long-term. In this study, the drought tolerant potato landrace Jancko Sisu Yari was treated with drought stress, rehydration and re-dehydration, and RNA-seq was applied to analyze the characteristics of gene regulation during these treatments. The results showed that drought-responsive genes mainly involved photosynthesis, signal transduction, lipid metabolism, sugar metabolism, wax synthesis, cell wall regulation, osmotic adjustment. Potato also can be recovered well in the re-emergence of water through gene regulation. The recovery of rehydration mainly related to patatin, lipid metabolism, sugar metabolism, flavonoids metabolism and detoxification besides the reverse expression of the most of drought-responsive genes. The previous drought stress can produce a positive responsive ability to the subsequent drought by drought hardening. Drought hardening was not only reflected in the drought-responsive genes related to the modified structure and cell components, but also in the hardening of gene expression or the “memory” of drought-responsive genes. Abundant genes involved photosynthesis, signal transduction, sugar metabolism, protease and protease inhibitors, flavonoids metabolism, transporters and transcription factors were subject to drought hardening or memorized drought in potato.

Reactive oxygen species (ROS), especially hydrogen peroxide, H₂O₂, act as signaling molecules to widely mediate growth, development, and stress response of plants. In the present study, internal ROS accumulation, effects of exogenous H₂O₂ treatment, the expression of the key tuberization-related genes, and the effect of knockout of Solanum tuberosum self-pruning 6A (StSP6A) on H₂O₂-induced tuber formation were investigated to elucidate whether and how H₂O₂ is involved in induction and formation of potato tubers using two diploid landraces, Solanum phureja and S. ajanhuiri. The results showed that there was a significant accumulation of ROS (including H₂O₂, superoxide anion, O₂⁻, and total ROS) during tuber induction and formation in stolons/tubers, especially in the hook-like subapical part of stolons prior to tuberization, as detected by staining observation and quantitative measurement. Furthermore, exogenous H₂O₂ treatment significantly enhanced percentage of tuber formation. By contrast, addition of either the ROS inhibitor diphenyleneiodonium chloride (DPI) or H₂O₂ scavenger catalase (CAT) resulted in a decline of tuber formation. In addition, expression analysis of nine key tuberization-related genes demonstrated that the H₂O₂-induced tuberization could be associated with H₂O₂-controlled regulation of these tuberization- and signaling-pathway-related genes, especially StSP6A, which was dramatically up-regulated during the early stage of tuber induction and H₂O₂ treatment. When StSP6A was knocked out by CRISPR-Cas9-mediated genome editing, the tuberization frequency of StSP6A null-mutants became significantly lower at various H₂O₂ concentration treatments. These findings indicate that H₂O₂ accumulation in stolons might play an important role by acting as a signaling molecule to initiate tuber induction, H₂O₂-induced tuber formation is triggered by regulating the tuberization-related gene expression and activating signal transduction pathways, and StSP6A is a pivotal player in H₂O₂-induced tuber formation in potato.