Trehalose is a nonreducing disaccharide containing two glucose molecules linked through an α,α-1,1-glycosidic bond. This unique chemical structure causes trehalose levels to fluctuate significantly in plants under stress, where it functions as an osmoprotectant, enhancing plant resistance to stress. Previous studies have confirmed that the trehalose synthesis pathway is widely conserved across most plants. However, the protective role of trehalose is limited only to organelles or tissues where the concentration is sufficiently high. In this review, we summarize previous reports on improving plant stress tolerance (drought, cold, heat, salt, pathogen, etc.) by applying trehalose-6-phosphate (T6P) or trehalose and manipulating the expression of trehalose metabolism-related genes. The molecular mechanisms underlying T6P, trehalose, and their related genes that regulate plant stress resistance are reviewed. More progressive studies on the spatiotemporal control of trehalose metabolism will provide a novel tool that allows for the simultaneous enhancement of crop yield and stress tolerance. We introduce the history of trehalose and discuss the possibility of trehalose and its metabolity-related genes binding to T6P to participate in stress response through unknown signaling pathways. In addition, the effects of trehalose metabolism regulation on plant growth and stress resistance were reviewed, and the molecular mechanism was fully discussed. In particular, we came up with new insights that the molecular mechanism of trehalose metabolism to enhance plant stress resistance in the future and we propose the need to use biotechnology methods to cultivate crops with stress resistance and high yield potential.

Various environmental stresses strongly influence plant development. Among these stresses is drought, which is a serious threat that can reduce agricultural productivity and obstruct plant growth. Although the mechanism of plants in response to drought has been studied extensively, the adaptive strategies of Amygdalus mira (Koehne) Yü et Lu grown in drought and rewatered habitats remain undefined. Amygdalus mira from the Tibetan Plateau has outstanding nutritional and medicinal values and can thrive in extreme drought. In this study, the physiological and proteomic responses in leaves of A. mira were investigated during drought and recovery period. The changes in plant growth, photosynthesis, enzymes, and non-enzymatic antioxidant under drought and rewatering were also analyzed in leaves. Compared with controls, A. mira showed stronger adaptive and resistant characteristics to drought. In addition, the proteomic technique was also used to study drought tolerance mechanisms in A. mira leaves. Differentially expressed proteins were identified using mass spectrometry. Accordingly, 103 proteins involved in 10 functional categories: cytoskeleton dynamics, energy metabolism, carbohydrate metabolism, photosynthesis, transcription and translation, transport, stress and defense, molecular chaperones, other materials metabolism, and unknown function were identified. These results showed that an increase of stress-defense-related proteins in leaves after drought treatment contributed to coping with drought. Importantly, A. mira developed an adaptive mechanism to scavenge reactive oxygen species (ROS), including enhancing antioxidant enzyme activities and non-enzymatic antioxidant contents, reducing energy, and adjusting the efficiency of gas exchanges. These results may help to understand the acclimation of A. mira to drought.

Drought stress can dramatically impair woody plant growth and restrict the geographical distribution of many tree species. To better understand the dynamics between the response and mechanism of Cupressus gigantea to drought and post-drought recovery, a comparative analysis was performed, relying on physiological measurements, RNA sequencing (RNA-Seq) and two-dimensional gel electrophoresis (2-DE) proteins. In this study, the analyses revealed that photosynthesis was seriously inhibited, while osmolyte contents, antioxidant enzyme activity and non-enzymatic antioxidant contents were all increased under drought stress in seedlings. Re-watering led to a recovery in most of the parameters analyzed, mainly the photosynthetic parameters and osmolyte contents. Transcriptomic and proteomic profiling suggested that most of the differentially expressed genes (DEGs) and differentially expressed proteins (DEPs) were specifically altered, and a few were consistently altered. Drought induced a common reduction in the level of DEGs and DEPs associated with photosynthesis. Notably, DEGs and DEPs involved in reactive oxygen species (ROS) scavenging, such as ascorbate oxidase and superoxide dismutase (SOD), showed an inverse pattern under desiccation. This study may improve our understanding of the underlying molecular mechanisms of drought resistance in C. gigantea and paves the way for more detailed molecular analysis of the candidate genes.

Bleeding is as particularly a serious phenomenon in Actinidia arguta and has important effects on this plant’s growth and development. Here we used A. arguta to study the effects of bleeding on the growth and development of leaves and fruits after a bleeding episode. We detect and analyze physiological indices of leaves and fruit after bleeding. The result revealed that the relative electrical conductivity and malondialdehyde (MDA) of leaves increased in treatment. Nitro blue tetrazolium chloride (NBT) and 3,3-diaminobenzidine (DAB) staining revealed the accumulation of reactive oxygen species (ROS) in leaves after bleeding. The chlorophyll content and photosynthetic parameter of plants were also decreased. In fruits, pulp and seed water content decreased after the damage, as did fruit vitamin C (Vc), soluble sugar content, and soluble solids content (SSC); the titratable acid content did not change significantly. We therefore conclude that bleeding affects the physiological indices of A. arguta. Our study provides a theoretical basis for understanding the physiological changes of A. arguta after bleeding episodes and laying a timely foundation for advancing research on A. arguta bleeding and long-term field studies should be executed in order to gain insights into underlying mechanisms.

Potato virus Y (PVY) is one of the most economically important pathogens of potato. PVY exhibits different phenotypes in dissimilar potato cultivars. Previously, we observed that two recombinant isolates, PVY^N-Wi-HLJ-BDH-2 (BDH) and PVY^NTN-NW(SYR-II)-INM-W-369-12 (369), exhibited different virulence levels in potato cultivar Kexin 13 despite high genome sequence identity. Indeed, 369 induced severe necrosis and plant death in severe cases in Kexin 13 and severe mosaic in cultivar Yanshu 8, whereas BDH caused mainly mosaic symptoms on the plants of both cultivars. We hypothesized that preinfection of plants with BDH could cross-protect them from 369 infection, and not vice versa. Challenge inoculation, either by mechanical wounding or through grafting, with 369 on plants that were preinfected with BDH did not augment the symptom expression in both cultivars. Reverse transcription quantitative PCR analysis showed that, after challenge inoculation with 369, the titer of the isolate on BDH-preinfected plants remained at a low level (about 3 × 10⁴ copy/µl) during the tested time course (0 h to 30 days). In contrast, in plants that were preinoculated with buffer (mock) and challenge inoculated with 369, the titer of 369 increased continuously until reaching its highest level of about 2 × 10⁷ (Yanshu 8) and about 4 × 10⁸ (Kexin 13) during the time course. Surprisingly, in plants that were preinfected with 369 and challenge inoculated with BDH, the accumulation of BDH reached nearly the same level as that in plants that were preinoculated with buffer and challenge inoculated with BDH. Taken together, these results suggest that PVY^N-Wi mediated cross-protection against PVY^NTN-NW(SYR-II) by superior competition and better fitness.