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.

Genome wide investigation of Hsf gene family in Phoebe bournei:identification,evolution,and expression after abiotic stresses

Heat shock transcription factors(Hsfs)have important roles during plant growth and development and responses to abiotic stresses.The identification and func-tion of Hsf genes have been thoroughly studied in various herbaceous plant species,but not woody species,especially Phoebe bournei,an endangered,unique species in China.In this study,17 members of the Hsf gene family were identi-fied from P.bournei using bioinformatic methods.Phyloge-netic analysis indicated that PbHsf genes were grouped into three subfamilies:A,B,and C.Conserved motifs,three-dimensional structure,and physicochemical properties of the PbHsf proteins were also analyzed.The structure of the PbHsf genes varied in the number of exons and introns.Pre-diction of cis-acting elements in the promoter region indi-cated that PbHsf genes are likely involved in responses to plant hormones and stresses.A collinearity analysis dem-onstrated that expansions of the PbHsf gene family mainly take place via segmental duplication.The expression levels of PbHsf genes varied across different plant tissues.On the basis of the expression profiles of five representative PbHsf genes during heat,cold,salt,and drought stress,PbHsf pro-teins seem to have multiple functions depending on the type of abiotic stress.This systematic,genome-wide investigation of PbHsf genes in P.bournei and their expression patterns provides valuable insights and information for further func-tional dissection of Hsf proteins in this endangered,unique species.

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 Correlation between Nutrition and Transport Mechanism under Abiotic Stress in Plants: A Comprehensive Review

Variations in the nutrients and water that plants require for metabolism,development,and the maintenance of cellular homeostasis are the main causes of abiotic stress in plants.It has,however,hardly ever been studied how these transporter proteins,such as aquaporin which is responsible for food and water intake in cell plasma mem-branes,interact with one another.This review aims to explore the interactions between nutrient transporters and aquaporins during water and nutrient uptake.It also investigates how symbiotic relationships influence the plant genome’s responses to regulatory processes such as photoperiodism,senescence,and nitrogenfixation.These responses are observed in reaction to various abiotic stresses.For instance,plasma membrane transporters are upregulated during macronutrient insufficiency,tonoplast transporters are overexpressed,and aquaporins are downregulated in micronutrient deficiency.Additionally,tolerant plants often exhibit increased expression of nutrient transporters and aquaporins in response to drought,salt,and cold temperatures.To better comprehend plant stress tolerance to abiotic challenges including starvation,K famine,salt,and freezing temperatures,both classes of nutrient and water transporters should be considered at the same time.

Genome-Wide Identification and Expression Analysis of the GSK3 Gene Family in Sunflower under Various Abiotic Stresses

Genes in the glycogen synthase kinase 3(GSK3)family are essential in regulating plant response to stressful conditions.This study employed bioinformatics to uncover the GSK3 gene family from the sunflower genome database.The expressions of GSK3 genes in different tissues and stress treatments,such as salt,drought,and cold,were assessed using transcriptome sequencing and quantitative real-time PCR(qRT-PCR).The study results revealed that the 12 GSK3 genes of sunflower,belonging to four classes(Classes I–IV),contained the GSK3 kinase domain and 11–13 exons.The majority of GSK3 genes were highly expressed in the leaf axil and flower,while their expression levels were relatively lower in the leaf.As a result of salt stress,six of the GSK3 genes(HaSK11,HaSK22,HaSK23,HaSK32,HaSK33,and HaSK41)displayed a notable increase in expression,while HaSK14 and HaSK21 experienced a significant decrease.With regard to drought stress,five of the GSK3 genes(HaSK11,HaSK13,HaSK21,HaSK22,and HaSK33)experienced a remarkable rise in expression.When exposed to cold stress,seven of the GSK3 genes(HaSK11,HaSK12,HaSK13,HaSK32,HaSK33,HaSK41,and HaSK42)showed a substantial increase,whereas HaSK21 and HaSK23 had a sharp decline.This research is of great importance in understanding the abiotic resistance mechanism of sunflowers and developing new varieties with improved stress resistance.

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.

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.

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.

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.

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.

Isolation of an Arabidopsis Gene Encoding Ins (1,3,4) P_3 5/6-Kinase-like Protein and Involved in Plant Response to Abiotic Stresses

By mRNA differential display from control versus NaCl_shocked Arabidopsis seedlings, we screened an Arabidopsis 3′ partial cDNA, which represents a gene encoding inositol 1,3,4_trisphosphate (Ins(1,3,4)P 3) 5/6_kinase_like protein. Northern blotting analysis showed that the gene, named as AtITL1, is strongly induced by NaCl and low temperature, but not induced by drought and abscisic acid (ABA). Analysis of 5′ region of the AtITL1 found that there are dehydration_responsive element/C_repeat (DRE/CRT) cis _acting elements, but no elements related to G_box and ABRE (ABA_responsive element) in its 5′ region, which is consistent with the expression patterns of the AtITL1 independent of ABA. These results suggest that the AtITL1 may be involved in the osmotic stress response pathway independent of ABA.

The Expression of RcLEA Gene Improves Tolerance of E. coli Cells to Abiotic Stress

[Objective] This study was to reveal the heat induced expression model of RcLEA gene and its tolerance to various abiotic stresses.[Method] Heat resistant and heat sensitive varieties of Rosa hybrida L.were subjected to heat shock treatment at 38 ℃ for 3 h;then RcLEA gene from both varieties treated was cloned and transformed into Escherichia coli strain BL21;finally recombinant colonies were separately cultured at 4 ℃ and 50 ℃ under the stresses of LiCl,NaCl,Na2CO3,CdCl2 and H2O2 to study the responses of recombinant E.coli strains to high temperature,low temperature and some other abiotic stresses.[Result] After heat shock treatment at 38 ℃ for 3 h,RcLEA gene expressed highly in ＇Schloss mannieim＇（SM）and ＇Las vegas＇（LV）variety,but weakly or even not expressed in ＇Kordes＇ Perfecta＇（KP）,indicating that this gene is closely related with heat resistance of R.hybrida.Compared with WT strains,recombinant clones showed higher tolerance to abiotic stresses including high temperature,low temperature,heavy metal,high salt,high pH value and oxidation,suggesting that RcLEA is concerned with the response of R.hybrida to abiotic stresses mentioned above.[Conclusion] These results provide thoughts for increasing heat resistance by introducing RcLEA into heat sensitive R.hybrida varieties and studying the heat-resistant mechanism of R.hybrida,and also provide theoretical support for selecting heat resistant variety of landscape and ornamental plants like R.hybrida.

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.

Verification of the resistance of a LEA gene from Tamarix expression in Saccharomyces cerevisiae to abiotic stresses

The role of late embryogenesis abundant （LEA） proteins in stress tolerance was examined by using a yeast expression system. LEA protein tolerance to the abotic stresses in plants involved in salt, drought and freezing stresses and additional tolerance to heat, NaHCO3 （salt-alkali） and ultraviolet radiation was also investigated. The transgenic yeast harboring the Tamarix LEA gene （DQ663481） was generated under the control of inducible GAL promoter （pYES2 vector）, yeast cells transformed with pYES2 empty vector were also generated as a control. Stress tolerance tests showed that LEA yeast transformants exhibited a higher survival rates than the control transformants under high temperature, NaHCO3, ultraviolet radiation, salt （NaCl）, drought and freezing, indicating that the LEA gene is tolerant to these abiotic stresses. These results suggest that the LEA gene is resistant to a wider repertoire of stresses and may play a common role in plant acclimation to the examined stress conditions.

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.

MdDREB2A in apple is involved in the regulation of multiple abiotic stress responses

Abiotic stress has a serious effect on plant growth.The transcription factor DREB2A is a member of the AP2/ERF family,which is widely involved in abiotic stress response.However,the function of apple MdDREB2A has not been systematically investigated.In this study,MdDREB2A was isolated from the cultivar‘Royal Gala’.The open reading frame of MdDREB2A was 1197 bp in length and it encoded a protein of 398 amino acidswithmolecularweight of 43.8 kD.As a transcription factor,MdDREB2Awas located in the nucleus.qRT-PCR analysis showed that MdDREB2A was involved in responses to drought,salt,and ABA stresses.Under these stress treatments,the relative electrical conductivity,superoxide anion and malondialdehyde(MDA)in transgenic materials significantly decreased,and the content of proline increased in MdDREB2A transgenic plants,compared to the controls,indicating that MdDREB2A transgenic apple calli and transgenic Arabidopsis exhibited improved resistance to abiotic stress.This study introduces a candidate gene for the genetic improvement of crop resistance and reveals important function of MdDREB2A in the regulation of abiotic stress response.

Roles of miR319-regulated TCPs in plant development and response to abiotic stress

Elaborate regulation of gene expression is required for plants to maintain normal growth,development,and reproduction.MicroRNAs(miRNAs)and transcription factors are key players that control gene expression in plant regulatory networks.The TEOSINTE BRANCHED1/CYCLOIDEA/PROLIFERATING CELL FACTOR(TCP)family comprises plantspecific transcription factors that contain a conserved TCP domain of 59 amino acids.Some members of this family are targeted by miR319,one of the most ancient and evolutionarily conserved miRNAs in plants.Accumulating evidence has revealed that miR319-regulated TCP(MRTCP)genes participate extensively in plant development and responses to environmental stress.In this review,the structural characteristics and classifications of TCP transcription factors and the regulatory relationships between TCP transcription factors and miRNAs are introduced.Current knowledge of the regulatory functions of MRTCP genes in multiple biological pathways including leaf development,vascular formation,flowering,hormone signaling,and response to environmental stresses such as cold,salt,and drought is summarized.This review will be beneficial for understanding the roles of the MRTCP-mediated regulatory network and its molecular mechanisms in plant development and stress response,and provides a theoretical basis for plant genetic improvement.

Genome-wide identification and transcriptome profiling reveal great expansion of SWEET gene family and their wide-spread responses to abiotic stress in wheat (Triticum aestivum L.)

The Sugars Will Eventually be Exported Jransporter(SWEET)gene family,identified as sugar transporters,has been demonstrated to play key roles in phloem loading,grain filling,pollen nutrition,and plant-pathogen interactions.To date,the study of SWEET genes in response to abiotic stress is very limited.In this study,we performed a genome-wide identification of the SWEET gene family in wheat and examined their expression profiles under mutiple abiotic stresses.We identified a total of 105 wheat SWEET genes,and phylogenic analysis revealed that they fall into five clades,with clade V specific to wheat and its closely related species.Of the 105 wheat SWEET genes,59%exhibited significant expression changes after stress treatments,including drought,heat,heat combined with drought,and salt stresses,and more up-regulated genes were found in response to drought and salt stresses.Further hierarchical clustering analysis revealed that SWEET genes exhibited differential expression patterns in response to different stress treatments or in different wheat cultivars.Moreover,different phylogenetic clades also showed distinct response to abiotic stress treatments.Finally,we found that homoeologous SWEET genes from different wheat subgenomes exhibited differential expression patterns in response to different abiotic stress treatments.The genome-wide analysis revealed the great expansion of SWEET gene family in wheat and their wide participation in abiotic stress response.The expression partitioning of SWEET homoeologs under abiotic stress conditions may confer greater flexibility for hexaploid wheat to adapt to ever changing environments.

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.

Cloning and Expression Analysis of an AP2/ERF Gene and Its Responses to Phytohormones and Abiotic Stresses in Rice

Ethylene response factors （ERFs） play important roles in response to plant biotic and abiotic stresses. In this study, a gene encoding a putative AP2/ERF domain-containing protein was isolated by screening a SSH cDNA library from rice and designated as Oryza sativa AP2/ERF-like protein （OsAP2LP） gene. OsAP2LP is 1491 bp in length, interrupted by seven introns, and encodes a putative protein of 348 amino acids. Temporal and spatial expression analysis showed that the OsAP2LP gene was preferentially expressed in roots, panicles, mature embryos and seeds in rice. Real-time quantitative PCR analysis indicated that the expression levels of the OsAP2LP gene were increased under the treatments of drought and gibberellin but decreased under the treatments of low temperature, salt, abscisic acid （ABA） and zeatin. Taken together, these results suggest that OsAP2LP might be involved in stress responses, and probably plays roles as a transcription regulator when plants response to cold, salt and drought stresses through ABA and gibberellin pathways.