Enhancing cold and drought tolerance in cotton: a protective role of SikCOR413PM1.

The present study explored the potential role of cold-regulated plasma membrane protein COR413PM1 isolated from Saussurea involucrata (Matsum. & Koidz)(SikCOR413PM1), in enhancing cotton (Gossypium hirsutum) tolerance to cold and drought stresses through transgenic methods. Under cold and drought stresses, the survival rate and the fresh and dry weights of the SikCOR413PM1-overexpressing lines were higher than those of the wild-type plants, and the degree of leaf withering was much lower. Besides, overexpressing SikCOR413PM1 overexpression increased the relative water content, reduced malondialdehyde content and relative conductivity, and elevated proline and soluble sugar levels in cotton seedlings. These findings suggest that SikCOR413PM1 minimizes cell membrane damage and boosts plant stability under challenging conditions. Additionally, overexpression of this gene upregulated antioxidant enzyme-related genes in cotton seedlings, resulting in enhanced antioxidant enzyme activity, lowered peroxide content, and reduced oxidative stress. SikCOR413PM1 overexpression also modulated the expression of stress-related genes (GhDREB1A, GhDREB1B, GhDREB1C, GhERF2, GhNAC3, and GhRD22). In field trials, the transgenic cotton plants overexpressing SikCOR413PM1 displayed high yields and increased environmental tolerance. Our study thus demonstrates the role of SikCOR413PM1 in regulating stress-related genes, osmotic adjustment factors, and peroxide content while preserving cell membrane stability and improving cold and drought tolerance in cotton.

Proper irrigation amount for eggplant cultivation in a solar greenhouse improved plant growth, fruit quality and yield by influencing the soil microbial community and rhizosphere environment.

Water scarcity is a worldwide problem, and in order to obtain plenty of production, agricultural irrigation water accounts for a large portion. Many studies have shown that the interaction of root microorganisms and soil can promote crop growth. Developing ways to reduce irrigation to maintain soil fertility and ensure crop yield by regulating the root microenvironment is an important research goal. Here, we developed a reasonable irrigation plan for eggplant cultivation in a solar greenhouse. The maximum theoretical amount of water demand during eggplant planting obtained from a previous study was used as the control (CK), and the irrigation in the treatments was reduced by 10, 20 and 30% relative to this amount. The 10% irrigation reduction treatment (T1) significantly improved soil nutrients and increased soil catalase, urease and alkaline phosphatase activities (p < 0.05). Further analysis of rhizosphere microorganisms revealed the highest richness and diversity of the microbial community under the T1 treatment, with Bacilli as the most abundant bacteria and Aspergillaceae as the most abundant fungi and lower relative abundances of Chloroflexi and Acidobacteria (p < 0.05). Changes in microbial community structure under the influence of different irrigation treatments resulted in improvements in rhizosphere N cycling and nutrient catabolism. The plant-microbe interactions led to significant increases in eggplant plant height, root vigour, root surface area, leaf chlorophyll a, leaf net photosynthetic rate, water use efficiency, transpiration rate, and stomatal conductance under the T1 treatment compared to the CK treatment; soluble sugar, soluble protein and free amino acid contents in eggplant fruit increased by 10.8, 12.3 and 6.7%, respectively; and yield increased by 3.9%. Our research proved that the 10% irrigation reduction treatment (T1) could improve microbial community richness and fruit yield, which would improve irrigation efficiency and cost reduction in agriculture.

The SikCuZnSOD3 gene improves abiotic stress resistance in transgenic cotton.

The expression of a gene encoding peroxisomal Cu-Zn superoxide dismutase from Saussurea involucrata Kar. et Kir. was induced by low temperature, PEG6000 treatment, and NaCl stress. To investigate the role of SikCuZnSOD3 in the mitigation of abiotic stress, we used Agrobacterium-mediated transformation to create transgenic cotton that overexpressed SikCuZnSOD3. Phenotypic analysis of T4 generation transgenic lines showed that they generally grew better than wild-type cotton under low temperature, PEG6000 treatment, and NaCl stress. Although there were no significant differences under control conditions, transgenic plants exhibited greater survival, fresh weight, and dry weight than wild-type plants under all three stress treatments. Additional physiological analyses demonstrated that the transgenic cotton had higher relative water content, proline and soluble sugar contents, and activity of antioxidant enzymes (superoxide dismutase, catalase, and peroxidase), as well as lower relative conductivity, malondialdehyde content, and H2O2 and O2- accumulation. More importantly, overexpression of SikCuZnSOD3 increased the yield of cotton fiber. Our results confirm that the overexpression of SikCuZnSOD3 can improve the abiotic stress resistance of cotton by increasing the activity of antioxidant enzymes, maintaining ROS homeostasis, and reducing cell membrane damage. Supplementary Information: The online version contains supplementary material available at 10.1007/s11032-021-01217-0.

Cold-regulated gene LeCOR413PM2 confers cold stress tolerance in tomato plants.

Tomato (Lycopersicon esculentum Mill) is an important food plant that has been used as a model plant in genetic evolution and molecular biology research. The plant is originated from the tropics; thus, it is sensitive to cold. Its growth and development can be easily affected by cold stress. In this study, cold-regulated gene LeCOR413PM2 was cloned from tomato leaves and then used to generate two types of transgenic tomato plants: LeCOR413PM2-overexpressing transgenic plants and RNA-interference-expressing transgenic plants. The functions and expression of LeCOR413PM2 gene in response to cold stress were subsequently assessed. The results showed that LeCOR413PM2 localized in the plasma membrane. Expression of LeCOR413PM2 gene in the leaf of transgenic tomato plant was highest compared to that in other organs (i.e., root, stem, flower and fruit); it was elevated when plants were treated with cold stress. Overexpression of LeCOR413PM2 gene was found to not only reduce damage to cell membrane, accumulation of ROS, and photoinhibition of PSII, but also maintain high activity of antioxidant enzymes and content of osmotic regulators. The results also reveal that high activities of antioxidant enzymes were caused by the up-regulation of their gene expressions. This study demonstrates that the overexpression of LeCOR413PM2 could increase cold tolerance of transgenic tomato plants, while the suppressed expression of LeCOR413PM2 by RNA interference could increase the sensitivity of plants to cold.

Heterotrimeric G-protein α subunit (LeGPA1) confers cold stress tolerance to processing tomato plants (Lycopersicon esculentum Mill).

BACKGROUND: Tomatoes (Lycopersicon esculentum Mill) are key foods, and their molecular biology and evolution have been well described. Tomato plants originated in the tropics and, thus, are cold sensitive. RESULTS: Here, we generated LeGPA1 overexpressing and RNA-interference (RNAi) transgenic tomato plants, which we then used to investigate the function of LeGPA1 in response to cold stress. Functional LeGPA1 was detected at the plasma membrane, and endogenous LeGPA1 was highly expressed in the roots and leaves. Cold treatment positively induced the expression of LeGPA1. Overexpression of LeGPA1 conferred tolerance to cold conditions and regulated the expression of genes related to the INDUCER OF CBF EXPRESSION-C-REPEAT-BINDING FACTOR (ICE-CBF) pathway in tomato plants. In the LeGPA1-overexpressing transgenic plants, the superoxide dismutase, peroxidase, and catalase activities and soluble sugar and proline contents were increased, and the production of reactive oxygen species and membrane lipid peroxidation decreased under cold stress. CONCLUSIONS: Our findings suggest that improvements in antioxidant systems can help plants cope with the oxidative damage caused by cold stress, thereby stabilizing cell membrane structures and increasing the rate of photosynthesis. The data presented here provide evidence for the key role of LeGPA1 in mediating cold signal transduction in plant cells. These findings extend our knowledge of the roles of G-proteins in plants and help to clarify the mechanisms through which growth and development are regulated in processing tomato plants.

Overexpression of SikRbcs2 gene promotes chilling tolerance of tomato by improving photosynthetic enzyme activity, reducing oxidative damage, and stabilizing cell membrane structure.

Red blood cell is a small subunit encoding 1, 5-ribulose bisphosphate carboxylase/ oxygenase (Rubisco). It could control the catalytic activity of Rubisco and play an important role in plant photosynthesis. SikRbcs2, a small subunit of Rubisco, is cloned from Saussurea involucrate. It has a strong low-temperature photosynthetic and photorespiration ability, but its mechanism in cold tolerance remains to be unknown. The results of quantitative PCR showed that SikRbcS2 gene could be induced by low-temperature, osmosis, and salt stress. Its expression was increased with the decrease of temperature, which was consistent with the habitat of Saussurea involucrata. Overexpression of Sikrbcs2 could significantly increase the mRNA expressions of SlrbcL and SlRCA in transgenic tomato seedlings. Furthermore, the activity and content of Rubisco and Rubisco activase (RCA) in transgenic tomato seedlings were also significantly higher than those in wild-type plants. The contents of chlorophyll and carotenoids, soluble sugar, and starch in the leaves of transgenic plants were significantly higher than those in WT plants, as well as the plant height, leaf area, and dry matter weight. Moreover, compared with WT, MDA content was decreased, and activities of SOD, POD, CAT, and APX were significantly higher in transgenic lines. In conclusion, our results suggested that overexpression of SikRbcs2 can reduce the damage of low temperature on photosynthesis of tomato seedlings. It could help achieve relatively stable photosynthesis, enhance scavenging ROS ability of tomato seedlings, maintain stable membrane structure, and improve cold tolerance of tomato.

The chilling tolerance divergence 1 protein confers cold stress tolerance in processing tomato.

Tomato (Lycopersicon esculentum Mill [Solanum lycopersicum L.].) is an important food material and cash crop, as well as a model plant for genetic evolution and molecular biology research. However, as a cold-sensitive crop originating from the tropics, the growth and development of tomato is often affected by low temperature stress. Therefore, how processing tomatoes resist this type of stress has important theoretical and practical significance. In this study, the LeCOLD1 gene was cloned from processing tomato. Subcellular localization analysis showed that LeCOLD1 was located in the plasma membrane. Real-time quantitative PCR analysis showed that LeCOLD1 was highly expressed in roots. Drought, salt and low temperatures induced the expression of COLD1. Overexpression and RNA interference vectors of LeCOLD1 were constructed and were transformed into tomato by the Agrobacterium-mediated method, and then obtaining transgenic tomato plants. It was found that LeCOLD1 increased the height of processing tomato plants and increased the length of their roots. In addition, overexpression of LeCOLD1 significantly improved the cold resistance of the plants. Overexpressing LeCOLD1 in tomato plants reduced the damage to the cell membrane, accumulation of ROS and photoinhibition of PSII, and maintained the high activity of antioxidant enzymes and the content of osmotic regulators. Further analysis revealed that during low temperature stress, the cells maintained high levels of antioxidant enzyme activity by regulating the transcription of the genes encoding these enzymes. The results show that overexpressing LeCOLD1 in tomato increases the plants' resistance to low temperatures, and that reducing LeCOLD1 expression makes the plants more sensitive to low temperatures.

Overexpression of Saussurea involucrata dehydrin gene SiDHN promotes cold and drought tolerance in transgenic tomato plants.

Dehydrins are late embryogenesis abundant proteins that help regulate abiotic stress responses in plants. Overexpression of the Saussurea involucrata dehydrin gene SiDHN has previously been shown to improve water-use efficiency and enhance cold and drought tolerance of transgenic tobacco. To understand the mechanism by which SiDHN exerts its protective function, we transformed the SiDHN gene into tomato plants (Solanum lycopersicum L.) and assessed their response to abiotic stress. We observed that in response to stresses, the SiDHN transgenic tomato plants had increased contents of chlorophyll a and b, carotenoid and relative water content compared with wild-type plants. They also had higher maximal photochemical efficiency of photosystem II and accumulated more proline and soluble sugar. Compared to those wild-type plants, malondialdehyde content and relative electron leakage in transgenic plants were not significantly increased, and H2O2 and O2- contents in transgenic tomato plants were significantly decreased. We further observed that the production of stress-related antioxidant enzymes, including superoxide dismutase, ascorbate peroxidase, peroxidase, and catalase, as well as pyrroline-5-carboxylate synthetase and lipid transfer protein 1, were up-regulated in the transgenic plants under cold and drought stress. Based on these observations, we conclude that overexpression of SiDHN gene can promote cold and drought tolerance of transgenic tomato plants by inhibiting cell membrane damage, protecting chloroplasts, and enhancing the reactive oxygen species scavenging capacity. The finding can be beneficial for the application of SiDHN gene in improving crop tolerance to abiotic stress and oxidative damage.

A novel cold-regulated protein isolated from Saussurea involucrata confers cold and drought tolerance in transgenic tobacco (Nicotiana tabacum).

Adverse environmental conditions, such as cold and drought, can inhibit plant growth, development, and productivity. The isolation and characterization of stress response genes from stress-tolerant plants can provide a better understanding of the underlying adaptive mechanisms. In this study, a novel cold-regulated gene, SikCOR413PM1, was isolated from Saussurea involucrata Kar. et Kir., which is a plant that survives at the high altitudes and in the low temperatures of alpine slopes in northwestern China. SikCOR413PM1 was induced in response to cold and drought in S. involucrata, and phylogenetic analysis revealed that the gene groups with a COR gene encoding a COR413PM protein family member. Subcellular localization of a SikCOR413PM1-green fluorescent fusion protein showed that SikCOR413PM1 was localized to the plasma membrane. A transgenic tobacco (Nicotiana tabacum) system was employed to investigate the possible role of SikCOR413PM1 in cold and drought tolerance. Analyses of growth, germination and survival rates, relative water content, malondialdehyde content, relative electrolyte leakage, and maximal photochemical efficiency of photosystem II showed that transgenic tobacco plants expressing SikCOR413PM1 were more tolerant to cold and drought stresses than WT plants. SikCOR413PM1 overexpression was also accompanied by constitutive activation of NtDREB1 and NtDREB3, two cold-responsive transcription factor genes, and NtERD10A and NtERD10B, two cold-induced genes. The expression levels of downstream transcription factor genes NtDREB3, NtERD10C, NtERD10D, and NtLEA5 were also induced in SikCOR413PM1-expressing transgenic plants under drought conditions. Our results suggest that the overexpression of SikCOR413PM1 induces changes in tobacco plants, and facilitates enhanced tolerance to cold and drought stresses.

Cloning and characterization of SiDHN, a novel dehydrin gene from Saussurea involucrata Kar. et Kir. that enhances cold and drought tolerance in tobacco.

Saussurea involucrata Kar. et Kir. is a hardy, dicotyledonous plant featured by strong tolerance to severe stress conditions. In a previous study, we created a cDNA library to characterize genetic factors associated with the cold acclimation response of S. involucrata. The full-length cDNA of one dehydrin-like gene, SiDHN, was obtained by RT-PCR and the SiDHN gene was further characterized in this study. The full-length SiDHN cDNA consists of 703 base pairs (bp) with a 333bp open reading frame encoding a protein comprising 111 amino acid residues. The alignment of the deduced amino acid sequence showed that SiDHN protein shared 36% identity with one homolog in Helianthus annuus. To evaluate its biological functions, 35S:SiDHN recombinant plasmid was introduced into tobacco using Agrobacterium tumefaciens and the resistance of transgenic plants to freezing and drought stresses were analyzed. Compared with the wild-type, transgenic tobacco plants showed greater resistance to freezing and drought stresses. In this study, we provided evidence that SiDHN can enhance plant cold and drought resistance, suggesting that SiDHN could be potentially used to genetically improve plant tolerance to abiotic stresses.