Hormetic effects of abiotic environmental stressors in woody plants in the context of climate change

Woody plants contribute to the stability and productivity of terrestrial ecosystems and are significantly affected by climate change.According to the concept of environmental hormesis,any environmental stressors can cause hormesis,that is,stimulation in low doses and inhibition in high doses.Numerous studies have demonstrated plant hormesis under low doses of various abiotic stressors.However,the hormetic responses of woody plants to abiotic stressors from climate change are insufficiently studied.This review analyses data on the stimulating effects of low doses of climate stressors in experiments and in real ecosystems.Numerous laboratory and field experiments show that single and combined exposure to various climate stressors(temperature,humidity,and elevated carbon dioxide concentrations) can cause hormesis in various species and functional types of woody plants,which can be accompanied by hormetic trade-offs and preconditioning.In addition,there is evidence of climate hormesis in woody plants in ecosystem conditions.Field experiments in various ecosystems show that elevated temperatures and/or precipitation or elevated carbon dioxide concentrations causing hormesis in dominant tree species can stimulate ecosystem productivity.Moreover,climate hormesis of the growth and reproduction of dominant forest tree species contributes to the spread of forests,that is,climate-driven ecological succession.The main commonalities of climate hormesis in woody species include:(1) Low-dose climate stressors cause hormesis in woody plants when strong(limiting) stressors do not affect plants or these limiting stressors are mitigated by climate change.(2) Hormesis can occur with the direct impact of climatic stressors on trees and with the indirect impact of these stressors on plants through other parts of the ecosystem.(3)Climate stressor interactions(e.g.,synergism,antagonism)can affect hormesis.(4) Hormesis may disappear due to tree acclimatization with consequent changes in the range of tolerances to climate factors.This review highlights the need for targeted studies of climate hormesis in woody species and its role in the adaptation of forest ecosystems to climate change.

Analysis and Characterization of the GABA Transaminase and Succinate Semialdehyde Dehydrogenase Genes in the Microalga Isochrysis zhanjiangensis in Response to Abiotic Stresses

Gamma-aminobutyric acid(GABA),widely existing in different organisms,is rapidly accumulated in plants in response to environmental stresses.The main biosynthesis and degradation pathways of GABA constitute the GABA shunt,which is tied to the tricarboxylic acid(TCA)cycle.GABA transaminase(GABA-T)and succinate semialdehyde dehydrogenase(SSADH)are two essential enzymes for the GABA degradation pathway.While there are abundant studies on GABA shunt in higher plants at the physiological and genetic levels,research on its role in microalgae remains limited.This study aimed at exploring the function of GABA-T and SSADH genes in Isochrysis zhanjiangensis,an important diet microalga,under different stresses.We cloned two GABA-T genes,IzGABA-T1 and IzGABA-T2,and one SSADH gene IzSSADH from Isochrysis zhanjiangensis and conducted heterologous expression experiments.The results showed that the overexpression of IzGABA-T1 or IzGABA-T2 enhanced the survival rates of yeast transformants under heat or NaCl stress,while the overexpression of IzSSADH improved yeast tolerance to NaCl stress but had no obvious effect on heat stress.Additionally,the results of quantitative real-time polymerase chain reaction(qPCR)showed that IzGABA-T1 transcription increased in the HT(salinity 25,35℃)and LS(salinity 15,25℃)groups.At 24 h,the IzGABA-T2 transcriptions increased in the HT,LS,and HS(salinity 35,25℃)groups,but their transcription levels decreased in all groups at 48 h.IzSSADH transcription increased in the LS group.These results suggest that IzGABA-T1,IzGABA-T2,and IzSSADH are associated with temperature and salinity stresses and possess a certain preference for different stresses.

Strategies and prospects for melatonin to alleviate abiotic stress in horticultural plants

Melatonin is a conserved pleiotropic molecule in animals and plants.Melatonin is involved in many development processes and stress responses;thus,exploring its function in plants,particularly in horticultural plants,has become a rapidly developing field.Many studies have revealed that phytomelatonin acts as a plant biostimulant and increase its tolerance to various abiotic stressors,including extreme temperature,drought,osmotic disturbance,heavy metals,and ultraviolet(UV).Melatonin appears to have roles in the scavenging of reactive oxygen species(ROS)and other free radicals,affecting the primary and secondary metabolism of plants,regulating the transcripts of stress-related enzymes and transcription factors,and crosstalk with other hormones under different environmental conditions.This pleiotropy makes phytomelatonin an attractive regulator to improve resistance to abiotic stress in plants.The recent discovery of the potential phytomelatonin receptor CAND2/PMTR1 and the proposition of putative models related to the phytomelatonin signaling pathways makes phytomelatonin a new plant hormone.Based on relevant studies from our laboratory,this review summarizes the phytomelatonin biosynthetic and metabolic pathways in plants and the latest research progress on phytomelatonin in abiotic stress of horticultural plants.This study will provide a reference for elucidating the regulatory mechanism of phytomelatonin affecting the resistance to abiotic stress in plants.

The effect of abiotic stresses on plant C:N:P homeostasis and their mitigation by silicon

In crop plants, various environmental stresses affect the balance of carbon, nitrogen, and phosphorus(C:N:P), leading to biochemical and physiological alterations and reductions in yield. Silicon(Si) is a beneficial element that alleviates plant stress. Most studies involving silicon have focused on physiological responses, such as improvements in photosynthetic processes, water use efficiency, and antioxidant defense systems. But recent research suggests that stressed plants facing either limited or excessive resources(water, light, nutrients, and toxic elements), strategically employ Si to maintain C:N:P homeostasis, thereby minimizing biomass losses. Understanding the role of Si in mitigating the impact of abiotic stresses on plants by regulating C:N:P homeostasis holds great potential for advancing sustainable agricultural practices in crop production. This review presents recent advances in characterizing the influence of environmental stresses on C:N:P homeostasis, as well as the role of Si in preserving C:N:P equilibrium and attenuating biological damage associated with abiotic stress. It underscores the beneficial effects of Si in sustaining C:N:P homeostasis and increasing yield via improved nutritional efficiency and stress mitigation.

Variation Characteristics of Root Traits of Different Alfalfa Cultivars under Saline-Alkaline Stress and their Relationship with Soil Environmental Factors

Soil salinization is the main factor that threatens the growth and development of plants and limits the increase of yield.It is of great significance to study the key soil environmental factors affecting plant root traits to reveal the adaptation strategies of plants to saline-alkaline-stressed soil environments.In this study,the root biomass,root morphological parameters and root mineral nutrient content of two alfalfa cultivars with different sensitivities to alkaline stress were analyzed with black soil as the control group and the mixed saline-alkaline soil with a ratio of 7:3 between black soil and saline-alkaline soil as the saline-alkaline treatment group.At the same time,the correlation analysis of soil salinity indexes,soil nutrient indexes and the activities of key enzymes involved in soil carbon,nitrogen and phosphorus cycles was carried out.The results showed that compared with the control group,the pH,EC,and urease(URE)of the soil surrounding the roots of two alfalfa cultivars were significantly increased,while soil total nitrogen(TN),total phosphorus(TP),organic carbon(SOC),andα-glucosidase activity(AGC)were significantly decreased under saline-alkaline stress.There was no significant difference in root biomass and root morphological parameters of saline-alkaline tolerant cultivar GN under saline-alkaline stress.The number of root tips(RT),root surface area(RS)and root volume(RV)of AG were reduced by 61.16%,44.54%,and 45.31%,respectively,compared with control group.The ratios of K^(+)/Na^(+),Ca^(2+)/Na^(+)and Mg^(2+)/Na^(+)of GN were significantly higher than those of AG(p<0.05).The root fresh weight(RFW)and dry weight(RDW),root length(RL),RV and RT of alfalfa were positively regulated by soil SOC and TN,but negatively regulated by soil pH,EC,and URE(p<0.01).Root Ca^(2+)/Na+ratio was significantly positively correlated with soil TN,TP and SOC(p<0.01).The absorption of Mg and Ca ions in roots is significantly negatively regulated by soilβ-glucosidase activity(BGC)and acid phosphatase activity(APC)(p<0.05).This study improved knowledge of the relationship between root traits and soil environmental factors and offered a theoretical framework for elucidating how plant roots adapt to saline-alkaline stressed soil environments.

Abiotic and Biotic Factors Controlling Grain Aroma along Value Chain of Fragrant Rice:A Review

The aroma of fragrant rice is one of the grain quality attributes that significantly influenceconsumer preferences and prices in world markets. The volatile compound 2-acetyl-1-pyrroline (2AP) isrecognized as a key component of the aroma in fragrant rice. The variation in grain 2AP content amongvarious fragrant rice varieties is associated with the expression of the badh2 gene, with 19 alleles havingbeen identified so far. The grain 2AP content is strongly influenced by environmental and managementfactors during cultivation as well as post-harvest conditions. This review pinpointed the major abiotic andbiotic factors that control grain 2AP content. Abiotic factors refer to water, temperature, light quality,fertilizer application (both macro- and micro-nutrients), and soil properties, including salinity, while bioticfactors include microorganisms that produce aromatic compounds, thus influencing the grain aroma infragrant rice. Post-harvest management, including storage and drying conditions, can significantly impactthe grain 2AP content, and proper post-harvest conditions can intensify the grain aroma. This reviewsuggests that there are rice varieties that can serve as potential sources of genetic material for breedingrice varieties with high grain aroma content. It offers an overview of recent research on the major factorsaffecting the aroma content in fragrant rice. This knowledge will facilitate further research on theproduction of high-quality rice to meet the demands of farmers and consumers.

Interplay between microglia and environmental risk factors in Alzheimer's disease

Alzheimer s disease,among the most common neurodegenerative disorders,is chara cterized by progressive cognitive impairment.At present,the Alzheimer’s disease main risk remains genetic ris ks,but major environmental fa ctors are increasingly shown to impact Alzheimer’s disease development and progression.Microglia,the most important brain immune cells,play a central role in Alzheimer’s disease pathogenesis and are considered environmental and lifestyle"sensors."Factors like environmental pollution and modern lifestyles(e.g.,chronic stress,poor dietary habits,sleep,and circadian rhythm disorde rs)can cause neuroinflammato ry responses that lead to cognitive impairment via microglial functioning and phenotypic regulation.However,the specific mechanisms underlying interactions among these facto rs and microglia in Alzheimer’s disease are unclear.Herein,we:discuss the biological effects of air pollution,chronic stress,gut micro biota,sleep patterns,physical exercise,cigarette smoking,and caffeine consumption on microglia;consider how unhealthy lifestyle factors influence individual susceptibility to Alzheimer’s disease;and present the neuroprotective effects of a healthy lifestyle.Toward intervening and controlling these environmental risk fa ctors at an early Alzheimer’s disease stage,understanding the role of microglia in Alzheimer’s disease development,and to rgeting strategies to to rget microglia,co uld be essential to future Alzheimer’s disease treatments.

Genome-wide identification of TPS genes in sesame and analysis of their expression in response to abiotic stresses

Trehalose and its precursor,trehalose-6-phosphate,play critical roles in plant metabolism and response to abiotic stresses.Trehalose-6-phosphate synthase(TPS)is a key enzyme in the trehalose synthesis pathway.Hence this study identified TPS genes in sesame(SiTPSs)and examined their expression patterns under various abiotic stresses.Totally,ten SiTPSs were identified and comprehensively characterized.SiTPSs were found to be unevenly distributed on five out of 13 sesame chromosomes and were predicted to be localized in chloroplasts and vacuoles of cells.Phylogenetic analysis classified SiTPS proteins into two groups(I and II),which was supported by gene structure and conserved motif analyses.Analysis of cis-acting elements in promoter regions of SiTPSs revealed that they might primarily involve developmental and environmental responses.SiTPSs exhibited different expression patterns in different tissues and under different abiotic stresses.Most group II SiTPS genes(SiTPS4-SiTPS10)were strongly induced by drought,salt,waterlogging,and osmotic stress.Particularly,SiTPS10 was the most significantly up-regulated under various abiotic stresses,indicating it is a candidate gene for improving sesame tolerance to multiple abiotic stresses.Our results provide insight into the TPS gene family in sesame and fundamental resources for genomics studies towards dissecting SiTPS genes’functions.

Mechanisms of autophagy function and regulation in plant growth,development,and response to abiotic stress

Autophagy is an evolutionarily conserved degradation pathway of lysosomes(in mammals)and vacuoles(in yeasts and plants)from lower yeasts to higher mammals.It wraps unwanted organelles and damaged proteins in a double-membrane structure to transport them to vacuoles for degradation and recycling.In plants,autophagy functions in adaptation to the environment and maintenance of growth and development.This review systematically describes the autophagy process,biological functions,and regulatory mechanisms occurring during plant growth and development and in response to abiotic stresses.It provides a basis for further theoretical research and guidance of agricultural production.

Defensive Role of Plant Hormones in Advancing Abiotic Stress-Resistant Rice Plants

Consistent climatic perturbations have increased global environmental concerns, especially the impacts of abiotic stresses on crop productivity. Rice is a staple food crop for the majority of the world’s population. Abiotic stresses, including salt, drought, heat, cold and heavy metals, are potential inhibitors of rice growth and yield. Abiotic stresses elicit various acclimation responses that facilitate in stress mitigation. Plant hormones play an important role in mediating the growth and development of rice plants under optimal and stressful environments by activating a multitude of signalling cascades to elicit the rice plant’s adaptive responses. The current review describes the role of plant hormone-mediated abiotic stress tolerance in rice, potential crosstalk between plant hormones involved in rice abiotic stress tolerance and significant advancements in biotechnological initiatives including genetic engineering approach to provide a step forward in making rice resistance to abiotic stress.

The nuclear export receptor OsXPO1 is required for rice development and involved in abiotic stress responses

The transport of proteins to and from the nucleus is necessary for many cellular processes and is one of the ways plants respond to developmental signals and environmental stresses.Nucleocytoplasmic trafficking of proteins is mediated by the nuclear transport receptor(NTR).Although NTR has been extensively studied in humans and Arabidopsis,it has rarely been identified and functionally characterized in rice.In this study,we identified exportin 1 in rice(OsXPO1)as a nuclear export receptor.OsXPO1shares high protein identity with its functional homologs in Arabidopsis and other organisms.OsXPO1localized to both the nucleus and the cytoplasm,directly interacted with the small GTPases OsRAN1and OsRAN2 in the nucleus,and mediated their nuclear export.Loss-of-function osxpo1 mutations were lethal at the seedling stage.Suppression of OsXPO1 expression in RNA interference lines produced multifaceted developmental defects,including arrested growth,premature senescence,abnormal inflorescence,and brown and mouth-opened spikelets.Overexpression of OsXPO1 in rice reduced plant height and seed-setting rate,but increased plant tolerance in response to PEG-mimicked drought stress and salt stress.These results indicate that OsXPO1 is a nuclear export receptor and acts in regulating plant development and abiotic stress responses.

Identification and Characterization of ZF-HD Genes in Response to Abscisic Acid and Abiotic Stresses in Maize

The zinc finger homeodomain(ZF-HD)genes belong to the homeobox gene family,playing critical roles in flower development and stress response.Despite their importance,however,to date there has been no genome-wide identification and characterization of the ZF-HD genes that are probably involved in stress responses in maize.In this study,24 ZF-HD genes were identified,and their chromosomal locations,protein properties,duplication patterns,structures,conserved motifs and expression patterns were investigated.The results revealed that the ZF-HD genes are unevenly distributed on nine chromosomes and that most of these genes lack introns.Six and two ZF-HD genes have undergone segmental and tandem duplication,respectively,during genome expansion.These 24 ZF-HD transcription factors were classified into six major groups on the basis of protein molecular evolutionary relationship.The expression profiles of these genes in different tissues were evaluated,resulting in producing two distinct clusters.ZF-HD genes are preferentially expressed in reproductive tissues.Furthermore,expression profiles of the 24 ZF-HD genes in response to different kinds of stresses revealed that ten genes were simultaneously up-regulated under ABA,salt and PEG treatments;meanwhile four genes were simultaneously down-regulated.These findings will pave the way for deciphering the function and mechanism of ZF-HD genes on how to implicate in abiotic stress.

Effects of Abiotic Environmental Factors on Soybean Cyst Nematode

As a pest, in order to complete its life history and reproduces effectively, soybean cyst nematode （SCN） （Heterodera glycines Ichinche 1952） must adapt to various environments and conditions for long periods of evolution. The nematode is widely dispersed year after year. Controlling this pest requires understanding characters and adaptability of SCN. Effects of abiotic factors, such as temperature, soil humidity, agrotype, pH value, ions, plant exudates, agricultural chemical and cultivation systems on SCN, are reviewed in this paper. The results show that SCN is able to endure various environmental stresses, especially low temperature. Because of its special life history, cyst stage help SCN over winter, resistance of SCN to environmental stress is strong. A few studies have reported the mechanism of SCN environmental adaptability. We emphasized the importance of studying environmental adaptability of SCN, which would benefit the control of SCN by ecological means.

Phytohormones and their metabolic engineering for abiotic stress tolerance in crop plants

Abiotic stresses including drought,salinity,heat,cold,flooding,and ultraviolet radiation causes crop losses worldwide.In recent times,preventing these crop losses and producing more food and feed to meet the demands of ever-increasing human populations have gained unprecedented importance.However,the proportion of agricultural lands facing multiple abiotic stresses is expected only to rise under a changing global climate fueled by anthropogenic activities.Identifying the mechanisms developed and deployed by plants to counteract abiotic stresses and maintain their growth and survival under harsh conditions thus holds great significance.Recent investigations have shown that phytohormones,including the classical auxins,cytokinins,ethylene,and gibberellins,and newer members including brassinosteroids,jasmonates,and strigolactones may prove to be important metabolic engineering targets for producing abiotic stress-tolerant crop plants.In this review,we summarize and critically assess the roles that phytohormones play in plant growth and development and abiotic stress tolerance,besides their engineering for conferring abiotic stress tolerance in transgenic crops.We also describe recent successes in identifying the roles of phytohormones under stressful conditions.We conclude by describing the recent progress and future prospects including limitations and challenges of phytohormone engineering for inducing abiotic stress tolerance in crop plants.

Genome-wide identification and analysis of the DREB genes and their expression profiles under abiotic stresses in Chinese jujube(Ziziphus jujuba Mill.)

CBF/DREB proteins play a critical role in abiotic stress-mediated gene expression and represent attractive regulons for plant breeding programs.However,no study has been conducted for CBF/DREB protein-related genes in jujube(Ziziphus jujuba Mill.).In this study,twenty-five ZjDREB genes were identified and annotated from the jujube(Z.jujuba‘Dongzao’)genome.Detailed analysis,including gene classification,annotation,phylogenetic evaluation,conserved motif determination and expression profiling were performed on all genes.Phylogenetic analysis showed that ZjDREB proteins were divided into five subgroups(A1–A5),but lacking a subgroup A6 corresponding to AtDREBs.The ZjDREB genes were distributed in nine of twelve chromosomes in the genome.Additionally,the expression patterns of the DREB genes under different abiotic stresses were investigated using q RT-PCR.Nineteen ZjDREB genes were down-regulated under low temperature,in contrast six ZjDREB genes(01,03,05,11,23 and 24)were up-regulated.Under drought,salinity and high temperature conditions,expression of ZjDREB03,09,10,14,15,17 and 20 genes were induced and showed similar expression patterns,suggesting that various stress conditions share common elements in the signaling pathway.The results suggest that the family of DREB genes play an important role in abiotic stresses in jujube,and provide a foundation for further functional studies of this important class of transcriptional regulators.

Isolation and Expression Patterns of Rice WRKY82 Transcription Factor Gene Responsive to Both Biotic and Abiotic Stresses

WRKY transcription factors are involved in the regulation of response to biotic and abiotic stresses in plants. A full-length cDNA clone of rice WRKY82 gene （OsWRKY82） was isolated from a cDNA library generated from leaves infected by Magnaporthe grisea. OsWRKY82 contained an entire open reading frame in length of 1 701 bp, and was predicted to encode a polypeptide of 566 amino acid residues consisting of two WRKY domains, each with a zinc finger motif of C2H2, belonging to the WRKY subgroup I. OsWRKY82 shared high identity at the amino acid level with those from Sorghum bicolor, Hordeum vulgare, and Zea mays. The transcript level of OsWRKY82 was relatively higher in stems, leaves, and flowers, and less abundant in grains. It was induced by inoculation with M. grisea and Rhizoctonia solani. However, the inducible expression in incompatible rice-M. grisea interactions was earlier and greater than that in compatible interactions. The expression of OsWRKY82 was up-regulated by methyl jasmonate and ethephon, whereas salicylic acid exerted no effects on its expression. Moreover, OsWRKY82 exhibited transcriptional activation ability in yeast. Additionally, OsWRKY82 transcripts could be induced by wounding and heat shocking, but not by abscisic acid, cold, high salinity and dehydration. By contrast, gibberellin suppressed the expression of OsWRKY82. These indicate that OsWRKY82 is a multiply stress-inducible gene responding to both biotic and abiotic stresses, and may be involved in the regulation of defense response to pathogens and tolerance against abiotic stresses by jasmonic acid/ethylene-dependent signaling pathway.

TaSAUR78 enhances multiple abiotic stress tolerance by regulating the interacting gene TaVDAC1

SMALL AUXIN-UP RNAs(SAURs) regulated by abiotic stress play multiple functions in plants. However, the functions of SAURs in abiotic stress are largely unknown. In this study, we cloned a novel SAUR gene, Ta SAUR78, from wheat, and we found that Ta SAUR78 interacted with Ta VDAC1(voltage-dependent anion channel). Salt stress decreased expression of Ta SAUR78 and increased expression of Ta VDAC1. Overexpression of Ta SAUR78 enhanced tolerance to salt, drought, and freezing stresses in transgenic Arabidopsis and reduced the accumulation of reactive oxygen species(ROS) under salt stress. Overexpression of Ta VDAC1 enhanced tolerance to salt stress, while decreased tolerance to drought and low temperature stresses in transgenic Arabidopsis. Ta VDAC1 overexpression increased the accumulation of ROS in plants. These results suggested that Ta SAUR78 improved plant tolerance to abiotic stresses by regulating Ta VDAC1. This study generated valuable information on the functions of Ta SAUR78 and Ta VDAC1 in multiple abiotic stresses, which may facilitate the deployment of these genes to enhance crop tolerance to abiotic stresses in the future.

Molecular Analysis of Rice CIPKs Involved in Both Biotic and Abiotic Stress Responses

Plant calcineurin B-like （CBL） proteins have been proposed as important Ca2＋ sensors and specifically interact with CBL-interacting protein kinases （CIPKs） in plant-specific calcium signaling. Here, we identified and isolated 15 CIPK genes in a japonica rice variety Nipponbare based on the predicted sequences of rice CIPK gene family. Gene structure analysis showed that these 15 genes were divided into intron-less and intron-rich groups, and OsCIPK3 and OsCIPK24 exhibited alternative splicing in their mature process. The phylogenetic analyses indicated that rice CIPKs shared an ancestor with Arabidopsis and poplar CIPKs. Analyses of gene expression showed that these OsCIPK genes were differentially induced by biotic stresses such as bacterial blight and abiotic stresses （heavy metal such as Hg2＋, high salinity, cold and ABA）. Interestingly, five OsCIPK genes, OsCIPK1, 2, 10, 11 and 12, were transcriptionally up-regulated after bacterial blight infection whereas four OsCIPK genes, OsCIPK2, 10, 11 and 14, were induced by all treatments, indicating that some of OsCIPK genes are involved in multiple stress response pathways in plants. Our finding suggests that CIPKs play a key role in both biotic and abiotic stress responses.

Dual function of Arabidopsis A TAF1 in abiotic and biotic stress responses

NAC 家庭基因编码涉及多样的生物过程的植物特定的抄写因素。在这研究， Arabidopsis NAC 基因 ATAF1 被发现被干旱导致，高咸度， abscisic 酸(骆驼毛的织物) ，甲基 jasmonate，机械伤害，并且 Botrytis cinerea 感染。ATAF1 的重要正式就职在受到干旱或高咸度的骆驼毛的织物缺乏的变异的 aba2 被发现，揭示表示的骆驼毛的织物无关的机制。Arabidopsis ATAF1-overexpression 线显示了许多改变的显型，包括侏儒症和短主要的根。而且，在 vivo，实验显示 ATAF1 是真正的管理者 modulating 植物对许多不能生活的压力和 necrotrophic 病原体感染的回答。在 Arabidopsis 的 ATAF1 的 Overexpression 增加了植物敏感到骆驼毛的织物，盐，和氧化压力。特别， ATAF1 overexpression 种，然而并非异种排队显示出的显著地提高的植物忍耐到干旱。另外， ATAF1 overexpression 提高了植物危险性到 necrotrophic 病原体 B。cinerea，但是没改变 P 的无毒害或剧毒的紧张引起的疾病症状。syringae pv 西红柿 DC3000。转基因的植物 overexpressing ATAF1 对氧化应力过分敏感，建议反应的氧中介可能与响应病原体和不能生活的压力的调停 ATAF1 的发信号有关。

Abiotic Stresses and Phytohormones Regulate Expression of FAD2 Gene in Arabidopsis thaliana

Modification of unsaturated fatty acid （FA） levels has been found to accompany multiple abiotic stress acclimations in many plants. Delta 12 fatty acid desaturase （FAD2） plays a critical role in the synthesis of polyunsaturated FAs in plant cells by converting oleic acid （18：1） to linoleic acid （18：2）. To better understand the relationship between polyunsaturated FAs metabolism and stress adaptation, the expression of FAD2 gene and changes in the FA compositions under various abiotic stresses and phytohormone treatments in Arabidopsis thaliana was investigated in this study. A 1 423-bp promoter of the FAD2 gene was cloned and characterized from Arabidopsis. Several putative hormone- and stress- inducible cis-elements were identified in the cloned promoter, which include salt- and pathogen-inducible GT-1 motifs, low-temperature-responsive MYC element, dehydration-responsive MYB element, and GA signaling related WRKY71OS element. To investigate the fine regulation of FAD2 gene, a recombinant FAD2 promoter-GUS construct was introduced into Arabidopsis plants. Histochemical study showed that the promoter was ubiquitously active and responsive not only to exogenous phytohormones including ABA, 24-eBL, and SA but also to darkness, temperature, salt, and sucrose stresses in Arabidopsis seedlings. Consistent with the expression change, treatments with exogenous 24-eBL, ABA, SA, and NaCl resulted in reduction in polyunsaturated FAs in Arabidopsis seedlings. These findings suggest that the FAD2 gene with a wide variety of putative response elements in its promoter is responsive to multiple phytohormones and abiotic stresses and therefore may play an important role in stress responses of Arabidopsis during plant growth and seed development.