Abiotic stresses, especially cold, salinity and drought, are the primary causes of crop loss worldwide. Plant adaptation to environmental stresses is dependent upon the activation of cascades of molecular networks involved in stress perception, signal transduction, and the expression of specific stress-related genes and metabolites. Plants have stress-specific adaptive responses as well as responses which protect the plants from more than one environmental stress. There are multiple stress perception and signaling pathways, some of which are specific, but others may cross-talk at various steps. In this review article, we first expound the general stress signal transduction pathways, and then highlight various aspects of biotic stresses signal transduction networks. On the genetic analysis, many cold induced pathways are activated to protect plants from deleterious effects of cold stress, but till date, most studied pathway is ICE-CBF-COR signaling pathway. The Salt-Overly-Sensitive (SOS) pathway, identified through isolation and study of the sos1, sos2, and sos3 mutants, is essential for maintaining favorable ion ratios in the cytoplasm and for tolerance of salt stress. Both ABA-dependent and -independent signaling pathways appear to be involved in osmotic stress tolerance. ROS play a dual role in the response of plants to abiotic stresses functioning as toxic by-products of stress metabolism, as well as important signal transduction molecules and the ROS signaling networks can control growth, development, and stress response. Finally, we talk about the common regulatory system and cross-talk among biotic stresses, with particular emphasis on the MAPK cascades and the cross-talk between ABA signaling and biotic signaling.

Low temperature is an abiotic stress that adversely affects the growth and production of plants. Resistance and adaptation of plants to cold stress is dependent upon the activation of molecular networks and pathways involved in signal transduction and the regulation of cold-stress related genes. Because it has numerous and complex genes, regulation factors, and pathways, research on the ICE-CBF-COR signaling pathway is the most studied and detailed, which is thought to be rather important for cold resistance of plants. In this review, we focus on the function of each member, interrelation among members, and the influence of manipulators and repressors in the ICE-CBF-COR pathway. In addition, regulation and signal transduction concerning plant hormones, circadian clock, and light are discussed. The studies presented provide a detailed picture of the ICE-CBF-COR pathway.

Adverse environmental conditions limit various aspects of plant growth, productivity, and ecological distribution. To get more insights into the signaling pathways under low temperature, we identified 10 C-repeat binding factors (), 9 inducer of CBF expression () and 10 cold-responsive () genes from - composite group under cold stress. Conserved amino acids analysis revealed that all CBF, ICE, COR contained specific and typical functional domains. Phylogenetic analysis of CBF proteins from showed that these CBF homologs were divided into 11 groups. CBFs from were found in every group, which shows that these CBFs generated prior to the divergence of the subfamilies of . The evolutionary relationship among the ICE and COR proteins in were divided into four groups with high multispecies specificity, respectively. Moreover, expression analysis revealed that mRNA accumulation was altered by cold treatment and the genes of three types involved in the ICE-CBF-COR signaling pathway were induced by cold stress. Together, the results make ,, genes family in more abundant, and provide a starting point for future studies on transcriptional regulatory network for improvement of chilling tolerance in crop.

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Background Plants are known to emit diverse volatile organic compounds (VOCs), which may function as signaling substances in plant communication with other organisms. Thuja occidentalis, which is widely cultivated throughout China, releases aromatic VOCs into the air in winter and early spring. The relationship of this cultivated plant with its neighboring plants is necessary for the conservation of biodiversity. Results (−)-α-thujone (60.34 ± 5.58%) was found to be the major component in VOCs from the Shenyang population. The essential oils (EOs) from the Kunming and Shenyang populations included the major components (−)-α-thujone, fenchone, (+)-β-thujone, and (+)-hibaene, identified using GC-MS analyses. (−)-α-thujone and (+)-hibaene were purified and identified by NMR identification. EOs and (−)-α-thujone exhibited valuable phytotoxic activities against seed germination and seedling growth of the plants Taraxacum mongolicum and Arabidopsis thaliana. Moreover, the EOs displayed potent inhibitory activity against pathogenic fungi of maize, including Fusarium graminearum, Curvularia lunata, and Bipolaris maydis, as well as one human fungal pathogen, Candida albicans. Quantitative analyses revealed high concentrations of (−)-α-thujone in the leaves of T. occidentalis individuals from both the Shenyang and Kunming populations. However, (−)-α-thujone (0.18 ± 0.17 μg/g) was only detected in the rhizosphere soil to a distance of 0.5 m from the plant. Conclusions Taken together, our results suggest that the phytotoxic effects and antifungal activities of the EOs and (−)-α-thujone in T. occidentalis certainly increased the adaptability of this plant to the environment. Nevertheless, low concentrations of released (−)-α-thujone indicated that reasonable distance of T. occidentalis with other plant species will impair the effects of allelochemical of T. occidentalis.

In plants, a promoter is essential to drive the transcription and expression of genes under stress conditions. The cold-regulated promoter is an important molecular switch involved in transcriptional regulation of a dynamic network of genes associated with cold acclimation processes. However, the structure and functions of the cold-regulated promoter are ambiguous. In this review, we first describe the common type and structures of the cold-regulated promoter, such as the core promoter and transcription factor binding sites, and then discuss the synergistic actions of promoter elements and cold-regulated genes. We also describe the transcriptional responses and cross-talk among cold-regulated genes in the ICE-CBF-COR cold-response pathway. Many stress-inducible genes are known to be regulated by endogenous abscisic acid (ABA), which accumulates during osmotic and cold stress. We discuss the regulation of promoters of cold-inducible genes in ABA-dependent and ABA-independent regulatory systems. We also describe the cross-talk among gene networks regulated by different cis-acting regulatory elements. Finally, we propose potential further research on, and practical applications of, the cold-regulated promoter.

Petroleum not only benefits the world economy but also contaminates the soil. In order to select the plants tolerant to petroleum, the physiological response of two petroleum tolerant-contrasting plants, Mirabilis jalapa and Orychophragmus violace, were investigated in variation of petroleum-contaminated soils (0, 5, 10, 20, and 40 g petroleum per kg soil) for 120 d. Petroleum degradation rate, seeds germination rate, free proline, and superoxide dismutase and peroxidase activities of M. jalapa were higher than that of O. violace under petroleum stress. However, the decrease rate of soluble protein, plant height, chlorophyll, and root fresh weight was greater in O. violace as compared to M. jalapa. Pearson correlation coefficient analysis was conducted, which indicated that the higher tolerance of M. jalapa was correlated with the higher level of free proline and antioxidative enzyme activities. Besides, the 10 g petroleum per kg soil may be appropriate for petroleum-tolerant plants selection, in which petroleum significantly restrain growth in O. violace but not in M. jalapa.

Using RT-PCR and rapid amplification of cDNA ends, two new full-length cDNAs of SAD (TaSAD1 and TaSAD2) were obtained from a hardiest winter wheat cultivar (Mironovskaya808). Sequence comparison analysis showed that the deduced amino acid sequences of TaSAD1 and TaSAD2 had high similarity to those of other reported SAD proteins. They were also different each other by some substitutions, insertions and/or deletions involving single amino acid residues or motifs. Based on evolution analysis, it was clear that all SAD genes from Poaceae were closer than those from other genus such as Arabidopsis, Glycine, Triadica, Brassica, Sesamum and Bassia. All SAD genes clustered into two major groups in Poaceae. Meanwhile, TaSAD1 and TaSAD2 were clustered into different groups. The tertiary structure prediction indicated that both TaSAD1 and TaSAD2 proteins were a compact globular protein and their model structures almost were the same.