Drought-responsive Proteins Research Articles

Actin cytoskeleton and plasma membrane aquaporins are involved in different drought response of Arabidopsis rhd2 and der1 root hair mutants

Actin cytoskeleton and reactive oxygen species are principal determinants of root hair polarity and tip growth. Loss of function in RESPIRATORY BURST OXIDASE HOMOLOG C/ROOT HAIR DEFECTIVE 2 (AtRBOHC/RHD2), an NADPH oxidase emitting superoxide to the apoplast, and in ACTIN 2, a vegetative actin isovariant, in rhd2-1 and der1-3 mutants, respectively, lead to similar defects in root hair formation and elongation Since early endosome-mediated polar localization of AtRBOHC/RHD2 depends on actin cytoskeleton, comparing the proteome-wide consequences of both mutations might be of eminent interest. Therefore, we employed a differential proteomic analysis of Arabidopsis rhd2-1 and der1-3 mutants. Both mutants exhibited substantial alterations in abundances of stress-related proteins. Notably, plasma membrane (PM)-localized PIP aquaporins showed contrasting abundance patterns in the mutants compared to wild-types. Drought-responsive proteins were mostly downregulated in rhd2-1 but upregulated in der1-3. Proteomic data suggest that opposite to der1-3, altered vesicular transport in rhd2-1 mutant likely contributes to the deregulation of PM-localized proteins, including PIPs. Moreover, lattice light sheet microscopy revealed reduced actin dynamics in rhd2-1 roots, a finding contrasting with previous reports on der1-3 mutant. Phenotypic experiments demonstrated a drought stress susceptibility in rhd2-1 and resistance in der1-3. Thus, mutations in AtRBOHC/RHD2 and ACTIN2 cause similar root hair defects, but they differently affect the actin cytoskeleton and vesicular transport. Reduced actin dynamics in rhd2-1 mutant is accompanied by alteration of vesicular transport proteins abundance, likely leading to altered protein delivery to PM, including aquaporins, thereby significantly affecting drought stress responses.

Elucidating hormone transduction and the protein response of soybean roots to drought stress based on ultra performance liquid chromatography–tandem mass spectrometry and four-dimensional data-independent acquisition

Drought stress can affect the growth and development of soybean, an important cultivated crop. As the main water-absorbing organ, it is particularly important to study the drought response mechanism of roots. Plant hormones are associated with almost all basic biological processes and are used as candidate targets for improving plant stress resistance by regulating cell signal transduction related to stress resistance. In this study, ultra performance liquid chromatography–tandem mass spectrometry (UPLC-MS/MS) and four-dimensional data-independent (4D-DIA) techniques were used to study the root hormone changes (5 %, 10 %, 15 % and 20 % drought stress level) and proteomic responses (15 % drought stress level) of different drought-tolerant varieties (drought-resistant HN44 and drought-sensitive HN65) under drought stress. The root activity, CAT activity and soluble sugar content of HN44 were basically higher than those of HN65 under different drought stress levels and days. In the two varieties, some plant hormones, such as abscisic acid (ABA) and salicylic acid (SA), accumulated with an increase in drought degree, and the accumulation of these hormones can give plants a certain degree of drought resistance. Most of the plant hormones peaked at 5–15 % drought stress level, and the overall content of jasmonic acid (JA) and cytokinin (CKs) decreased. Differences in the expression of key enzymes involved in hormone signal transduction, such as GH3, TCH4, and PR1, affect a variety of processes and lead to differences in drought resistance between the two varieties. In addition, HN44 had more upregulated proteins in important antioxidant pathways such as glutathione metabolism, phenylpropanoid biosynthesis, and isoflavone biosynthesis. Important drought-responsive proteins, such as PAL, 4CL, and VR, have also been characterized in HN44. In general, the drought-resistant variety was substantially better than the drought-sensitive variety in terms of hormone signaling and antioxidant capacity. These candidate proteins can be used as potential targets for improving drought resistance.

The roles of plant proteases and protease inhibitors in drought response: a review.

Upon exposure to drought, plants undergo complex signal transduction events with concomitant changes in the expression of genes, proteins and metabolites. For example, proteomics studies continue to identify multitudes of drought-responsive proteins with diverse roles in drought adaptation. Among these are protein degradation processes that activate enzymes and signalling peptides, recycle nitrogen sources, and maintain protein turnover and homeostasis under stressful environments. Here, we review the differential expression and functional activities of plant protease and protease inhibitor proteins under drought stress, mainly focusing on comparative studies involving genotypes of contrasting drought phenotypes. We further explore studies of transgenic plants either overexpressing or repressing proteases or their inhibitors under drought conditions and discuss the potential roles of these transgenes in drought response. Overall, the review highlights the integral role of protein degradation during plant survival under water deficits, irrespective of the genotypes' level of drought resilience. However, drought-sensitive genotypes exhibit higher proteolytic activities, while drought-tolerant genotypes tend to protect proteins from degradation by expressing more protease inhibitors. In addition, transgenic plant biology studies implicate proteases and protease inhibitors in various other physiological functions under drought stress. These include the regulation of stomatal closure, maintenance of relative water content, phytohormonal signalling systems including abscisic acid (ABA) signalling, and the induction of ABA-related stress genes, all of which are essential for maintaining cellular homeostasis under water deficits. Therefore, more validation studies are required to explore the various functions of proteases and their inhibitors under water limitation and their contributions towards drought adaptation.

Enriching drought resistance in Solanum lycopersicum using Abscisic acid as drought enhancer derived from Lygodium japonicum: A new-fangled computational approach.

Drought is the largest abiotic factor impacting agriculture. Plants are challenged by both natural and artificial stressors because they are immobile. To produce drought-resistant plants, we need to know how plants react to drought. A largescale proteome study of leaf and root tissue found drought-responsive proteins. Tomato as a vegetable is grown worldwide. Agricultural biotechnology focuses on creating drought-resistant cultivars. This is important because tomato drought is so widespread. Breeders have worked to improve tomato quality, production, and stress resistance. Conventional breeding approaches have only increased drought tolerance because of drought's complexity. Many studies have examined how tomatoes handle drought. With genomics, transcriptomics, proteomics, metabolomics, and modern sequencing technologies, it's easier to find drought-responsive genes. Biotechnology and in silico studies has helped demonstrate the function of drought-sensitive genes and generate drought-resistant plant types. The latest tomato genome editing technology is another. WRKY genes are plant transcription factors. They help plants grow and respond to both natural and artificial stimuli. To make plants that can handle stress, we need to know how WRKY-proteins, which are transcription factors, work with other proteins and ligands in plant cells by molecular docking and modeling study. Abscisic acid, a plant hormone generated in stressed roots, was used here to make plants drought-resistant. Abscisic acid binds WRKY with binding affinity -7.4kcal/mol and inhibitory concentration (Ki) 0.12 microM. This study aims to modulate the transcription factor so plants can handle drought and stress better. Therefore, polyphenols found to make Solanum lycopersicum more drought-tolerant.

Drought stress memory in rice guard cells: Proteome changes and genomic stability of DNA

Drought is one of the major threats for crop plants among them rice, worldwide. The effects of drought vary depending on the plant growth phase and the occurrence of a previous stress, which can leave a memory of the stress. Stomata guard cells perform many essential functions and are highly responsive to hormonal and environmental stimuli. Therefore, information on how guard cells respond to drought might be useful for selecting drought tolerant plants. In this work, physiological analysis, comparative proteomics, gene expression and 5 – methylcytosine (%) analysis were used to elucidate the effects of drought in single stress event at vegetative or reproductive stage or recurrent at both stages in guard cells from rice plants. Photosynthesis and stomatal conductance decreased when drought was applied at reproductive stage in single and recurrent event. Twelve drought-responsive proteins were identified, belonging to photosynthesis pathway, response to oxidative stress, stress signalling and others. The expression of their encoding genes showed a positive relation with the protein abundance. Drought stress increased the total DNA methylation when applied at vegetative stage in single (35%) and recurrent event (18%) and decreased it in plants stressed at reproductive stage (9.8%), with respect to the levels measured in well-watered ones (13.84%). In conclusion, a first drought event seems to induce adaptation to water-deficit conditions through decreasing energy dissipation, increasing ATP energy provision, reducing oxidative damage in GC. Furthermore, the stress memory is associated with epigenetic markers.

Rice lectin protein r40c1 imparts drought tolerance by modulating S-adenosylmethionine synthase 2, stress-associated protein 8 and chromatin-associated proteins.

Lectin proteins play an important role in biotic and abiotic stress responses in plants. Although the rice lectin protein Osr40c1 has been reported to be regulated by drought stress, the mechanism of its drought tolerance activity has not been studied so far. In this study, it is shown that expression of the Osr40c1 gene correlates with the drought tolerance potential of various rice cultivars. Transgenic rice plants overexpressing Osr40c1 were significantly more tolerant to drought stress than the wild-type plants. Furthermore, ectopic expression of the Osr40c1 gene in tobacco yielded a similar result. Interestingly, the protein displayed a nucleo-cytoplasmic localization and was found to interact with a number of drought-responsive proteins such as S-adenosylmethionine synthase 2 (OsSAM2), stress-associated protein 8 (OsSAP8), DNA-binding protein MNB1B (OsMNB1B), and histone 4 (OsH4). Silencing of each of these protein partners led to drought sensitivity in otherwise tolerant Osr40c1-expressing transgenic tobacco lines indicating that these partners were crucial for the Osr40c1-mediated drought tolerance in planta. Moreover, the association of Osr40c1 with these partners occurred specifically under drought stress forming a multi-protein complex. Together, our findings delineate a novel role of Osr40c1 in imparting drought tolerance by regulating OsMNB1B, OsSAM2, and OsH4 proteins, which presumably enables OsSAP8 to induce downstream gene expression.

Comparative proteomic analysis of drought and high temperature response in roots of two potato cultivars

A comparative analysis of drought and high temperature responsive proteins, which means to provide insight into the molecular mechanism of potato stress tolerance. In the presented study, two potato cultivars, differing in dehydration tolerance, were compared. An analysis of their morphological, physiological and root proteome related traits proved that, although water shortage, as well as high temperatures cause the dehydration of plants, the response to those stresses at the proteome level was significantly different. LC–MS/MS protein identification showed that in roots of the sensitive cultivar, in response to drought, most changes concern increased abundance of defence- and detoxification-related proteins, while in tolerant plants, significant changes in abundance of energy and carbohydrate metabolism related proteins were observed (data are available via ProteomeXchange with identifier PXD020259). Moreover, in response to high temperatures, in the sensitive cultivar, decreased abundance of proteins involved in cell energetic metabolism was detected, while in the tolerant cultivar, the majority of proteins from this group was abundant. It can be suggested that such comparative proteome analysis indicates the fine tuning metabolism as a major factor of stress tolerance of potato plants.

Tandem mass tag-based (TMT) quantitative proteomics analysis reveals the response of fine roots to drought stress in cotton (Gossypium hirsutum L.)

BackgroundCotton (Gossypium hirsutum L.) is one of the most important cash crops worldwide. Fine roots are the central part of the root system that contributes to plant water and nutrient uptake. However, the mechanisms underlying the response of cotton fine roots to soil drought remains unclear. To elucidate the proteomic changes in fine roots of cotton plants under drought stress, 70–75% and 40–45% soil relative water content treatments were imposed on control (CK) and drought stress (DS) groups, respectively. Then, tandem mass tags (TMT) technology was used to determine the proteome profiles of fine root tissue samples.ResultsDrought significantly decreased the value of average root diameter of cotton seedlings, whereas the total root length and the activities of antioxidases were increased. To study the molecular mechanisms underlying drought response further, the proteome differences between tissues under CK and DS treatments were compared pairwise at 0, 30, and 45 DAD (days after drought stress). In total, 118 differentially expressed proteins (DEPs) were up-regulated and 105 were down-regulated in the ‘DS30 versus CK30’ comparison; 662 DEPs were up-regulated, and 611 were down-regulated in the ‘DS45 versus CK45’ comparison. The functions of these DEPs were classified according to their pathways. Under early stage drought (30 DAD), some DEPs involved in the ‘Cutin, suberin, and wax synthesis’ pathway were up-regulated, while the down-regulated DEPs were mainly enriched within the ‘Monoterpenoid biosynthesis’ pathway. Forty-five days of soil drought had a greater impact on DEPs involved in metabolism. Many proteins involving ‘Carbohydrate metabolism,’ ‘Energy metabolism,’ ‘Fatty acid metabolism,’ ‘Amino acid metabolism,’ and ‘Secondary metabolite biosynthesis’ were identified as DEPs. Additionally, proteins related to ion transport, stress/defense, and phytohormones were also shown to play roles in determining the fine root growth of cotton plants under drought stress.ConclusionsOur study identified potential biological pathways and drought-responsive proteins related to stress/defense responses and plant hormone metabolism under drought stress. Collectively, our results provide new insights for further improving drought tolerance in cotton and other crops.

Identification of Drought-Responsive Proteins of Sensitive and Tolerant Tea (Camellia sinensis L) Clones under Normal and Drought Stress Conditions

Background: Tea is one of the most popular calming drinks. Drought is a major environmental factor that limited the growth and development of plants. Objective: : Therefore, the identification of proteins under the drought stress conditions in tea can have an essential role in the breeding programs and tea production. Methods:: For this purpose, 14 tea clones were studied under normal and drought stress conditions in two separate experiments, and the leaves of the clones were stored at −80°C. After the identification of two clones (100 and 278) as tolerant and sensitive clones, respectively, the proteomics approach was used to compare the leaf protein profile changes under both conditions. Results:: The results of proteomics showed about 500 detectable protein spots, of which 250 spots were repeatable. Among the 250 reproducible spots, 16 spots responded to the drought stress, which showed the highest amount of variation among the treatments. Thioredoxin, peroxidase, superoxide dismutase, ribosomal protein, and hsp70 were mentioned among the identified proteins. These proteins were involved in various cellular functions. Conclusion:: Identified proteins also had a crucial role in regulating carbohydrate and nitrogen metabolism and the scavenging of the Reactive Oxygen Species (ROS). Upregulation of proteins involved in protein processing (ribosomal protein), oxygen species scavenging, and defense (Superoxide dismutase, Peroxidase, and thioredoxin) may increase plant adaptation to drought stress. This study was the first report that showed ribosomal protein L32 was significantly changed in tea against drought stress response. Therefore, these proteins can protect the plant against drought stress. This study partially identified the drought stress proteins in the tea plant.

Comparative proteomics analysis reveals important drought responsive proteins in the leaves of a potato variety tolerant to drought stress

Comparative proteomics analysis reveals important drought responsive proteins in the leaves of a potato variety tolerant to drought stress

Identification and in-silico Analysis of Drought-Responsive Putative Boiling Soluble Proteins (Hydrophilins) Related Genes from Triticum aestivum

The biochemical features that govern multi-functions of boiling soluble proteins are still not well documented. This study reports isolation and sequencing of a water stress responsive cDNA which encodes dehydrin-like boiling soluble proteins (designated as TaBsSRP1 and TaBsSRP2: Triticum aestivum boiling soluble stress responsive proteins) from seedlings exposed to water stress from wheat (PBW 175) cultivar tolerant to drought stress. In addition we described in-silico analysis of TaBsSRP1 through computational approaches. The physio-chemical analysis of TaBsSRP1 revealed that it belongs to group 3 LEA protein. Based upon these findings we suggest the possible mechanism that how these boiling soluble proteins preclude the unfavourable effect of drought stress.

Physiological and proteomic responses to drought stress in leaves of two wild grapevines (Vitis sylvestris): a comparative study

Grapevine is one of the most important fruit crops in the world, which is severely threatened by drought. Therefore, understanding grapevine drought response mechanisms is needed to develop grapevine cultivars that can tolerate this stress. In the present report, a comparative proteomic study using 2D-PAGE was performed on two wild grapevine accessions, Tebaba (salt tolerant) and Houamdia (salt sensitive), to identify proteins that play key roles in drought responsive mechanisms. Plants were exposed to water deficit stress for 16 days. Physiological observations did not indicate any difference in drought tolerance between the two accessions. However, the comparative proteomic study showed that 18 drought-responsive proteins changed in both accessions under drought stress and 48 (29 in Houamdia and 19 in Tebaba) were variety specific. Based on changes in protein abundance induced by drought stress, carbohydrate and energy metabolism were similarly up-regulated in both accessions. Amino acid metabolism was more negatively affected by the stress in Houamdia accession. Interestingly, the three ROS scavenging proteins APX, ASR2 and GRXS17 were up-regulated only in Tebaba. Some drought-responsive proteins, such as RBP, RuBisCO, RCA, 26S protease, CLpA and 14–3-3-like protein were up-regulated by the stress in Tebaba, whereas they were down-regulated in Houamdia. Taken together, these results suggest that Tebaba may alleviate drought stress through an activation of photosynthesis and redox reactions, and a degradation of misfolded/damaged proteins. Information given in this report could be helpful for selecting candidate proteins/genes as markers in improving drought tolerance in grapevine cultivars.

Translocation of Drought-Responsive Proteins from the Chloroplasts.

Some chloroplast proteins are known to serve as messengers to transmit retrograde signals from chloroplasts to the nuclei in response to environmental stresses. However, whether particular chloroplast proteins respond to drought stress and serve as messengers for retrograde signal transduction are unclear. Here, we used isobaric tags for relative and absolute quantitation (iTRAQ) to monitor the proteomic changes in tobacco (Nicotiana benthamiana) treated with drought stress/re-watering. We identified 3936 and 1087 differentially accumulated total leaf and chloroplast proteins, respectively, which were grouped into 16 categories. Among these, one particular category of proteins, that includes carbonic anhydrase 1 (CA1), exhibited a great decline in chloroplasts, but a remarkable increase in leaves under drought stress. The subcellular localizations of CA1 proteins from moss (Physcomitrella patens), Arabidopsis thaliana and rice (Oryza sativa) in P. patens protoplasts consistently showed that CA1 proteins gradually diminished within chloroplasts but increasingly accumulated in the cytosol under osmotic stress treatment, suggesting that they could be translocated from chloroplasts to the cytosol and act as a signal messenger from the chloroplast. Our results thus highlight the potential importance of chloroplast proteins in retrograde signaling pathways and provide a set of candidate proteins for further research.

Proteomic Responses to Drought Vary Widely Among Eight Diverse Genotypes of Rice (Oryza sativa).

Rice is a critically important food source but yields worldwide are vulnerable to periods of drought. We exposed eight genotypes of upland and lowland rice (Oryza sativa L. ssp. japonica and indica) to drought stress at the late vegetative stage, and harvested leaves for label-free shotgun proteomics. Gene ontology analysis was used to identify common drought-responsive proteins in vegetative tissues, and leaf proteins that are unique to individual genotypes, suggesting diversity in the metabolic responses to drought. Eight proteins were found to be induced in response to drought stress in all eight genotypes. A total of 213 proteins were identified in a single genotype, 83 of which were increased in abundance in response to drought stress. In total, 10 of these 83 proteins were of a largely uncharacterized function, making them candidates for functional analysis and potential biomarkers for drought tolerance.

The chloroplast proteome response to drought stress in cassava leaves

Cassava is an important tropical crop with strong resistance to drought stress. The chloroplast, the site of photosynthesis, is sensitive to stress, and the drought-response proteins in cassava chloroplasts are worthy of investigation. In this study, cassava leaves were collected for ultra-structure observation from plants subjected to different drought stress conditions. Our results showed that drought stress can promote starch accumulation in cassava chloroplasts. To evaluate changes in chloroplast proteins under different drought conditions, two-dimensional electrophoresis was performed using purified chloroplasts, which resulted in the identification of 26 unique chloroplast proteins responsive to drought stress. These drought-responsive proteins are predominantly related to photosynthesis, carbon and nitrogen metabolism, and amino acid metabolism. Among them, most photosynthesis-related proteins are downregulated, with decreases in photosynthetic parameters upon drought stress. Several proteins associated with carbon and nitrogen metabolism, including rubisco and carbonic anhydrase, were upregulated, which might promote drought tolerance in cassava by enhancing the carbohydrate conversion efficiency and protecting the plant from oxidative stress. Our proteomic data not only provide insight into the complement of proteins in cassava chloroplasts but also further our overall understanding of drought-responsive proteins in cassava chloroplasts.

Physiology and proteomics of two maize genotypes with different drought resistance

The aim of this study was to investigate the physiological basis and molecular mechanism of genotypic variation in drought response of maize seedlings. Comparative physiological and proteomic analyses were conducted in the leaves of drought-tolerant Liyu 35 (LY) and drought-sensitive Denghai 605 (DH) maize genotype seedlings. Drought induced a significant decrease of relative water content and osmotic potential of leaves, length and volume of roots, and total dry weight, but significantly increased malondialdehyde in DH seedlings. However, root dry weight , proline content and antioxidant enzyme activities increased more in LY than in DH. Forty-two spots in LY and 17 spots in DH that showed significant abundance variations were identified by matrix-assisted laser desorption/ionization time-of-flight/time-of-flight mass spectrometry. These drought-responsive proteins were mainly involved in biological processes of photosynthesis, defense and oxidative stress, carbohydrate and energy metabolism, protein synthesis and processing, and cell wall biogenesis and degradation. Among them, proteins involved in defense and oxidative stress, and protein synthesis and processing were largely enriched in the LY genotype, which may contribute to a natural variation of drought resistance between LY and DH genotypes. The altered protein abundance and corresponding physiological-biochemical response shed some light on molecular mechanisms related to drought tolerance in drought-tolerant maize and provide key candidate proteins for genetic improvement of maize.

Identification of drought responsive proteins and related proteomic QTLs in barley.

Drought is a major abiotic stress that negatively influences crop yield. Breeding strategies for improved drought resistance require an improved knowledge of plant drought responses. We therefore applied drought to barley recombinant inbred lines and their parental genotypes shortly before tillering. A large-scale proteomic analysis of leaf and root tissue revealed proteins that respond to drought in a genotype-specific manner. Of these, Rubisco activase in chloroplast, luminal binding protein in endoplasmic reticulum, phosphoglycerate mutase, glutathione S-transferase, heat shock proteins and enzymes involved in phenylpropanoid biosynthesis showed strong genotype×environment interactions. These data were subjected to genetic linkage analysis and the identification of proteomic QTLs that have potential value in marker-assisted breeding programs.

Drought stress induces a biphasic NO accumulation in Arabidopsis thaliana

ABSTRACTWe have recently reported the proteomic signature of the early (≤30 min) drought stress responses in Arabidopsis thaliana suspension cells challenged with PEG. We found an over-representation in the gene ontology categories “Ribosome” and “Oxidative stress along with an increased abundance of late embryogenesis abundant (LEA) and early response to dehydration (ERD) proteins. Since nitric oxide (NO) plays a pivotal role in plant responses to drought stress and induces LEA and DREB proteins, here we monitored the levels of NO in Arabidopsis cell suspensions and leaf disks challenged with PEG, and performed comparative analyses of the proteomics and transcriptomics data in public domain to search for a common set of early drought and NO responsive proteins.We show that under drought-stress, NO shows a biphasic time course, much like in response to ozone stress and that among the early drought and NO responsive proteins, the categories “DNA binding”, “Nucleotide binding” and “Transcription regulator activity” are enriched. Taken together, present study suggests that in Arabidopsis the changing NO levels may play a critical role in early drought responsive processes and notably in the transcriptional and translational reprograming observed under drought stress.

Identification of drought stress-responsive proteins in common bean

Proteomics has emerged as a vital tool for high throughput systematic analysis of protein expression which helps to unlock various biochemical pathways. Keeping in view the relevance of differential expression studies at the post transcriptional level, we attempted to explore the candidate proteins that are triggered under low water stress conditions at vegetative and reproductive stages in common bean. The evaluation of drought-responsive proteins was performed by resolving the quantified protein extracted from leaf samples using SDS PAGE for detection of differential bands followed by trypsin digestion and MALDI-MS analysis. We report the presence of seven significant proteins where five proteins (Glucan endo-1.3 beta-glucosidase, Auxin-responsive protein, Endochitinase, Endochitinase CH5B and L-type lectin domain containing receptor kinase IV.3) were upregulated and two proteins (Ribulose bisphosphate carboxylase/oxygenase activase, ADP-ribosylation factor-like protein 8a) were down regulated. The study conducted herein indicates the strong interaction and varied activation of proteins at both the developmental stages. The identified proteins are primarily localized in nucleus, cell membrane, cytoskeleton, vacuole and chloroplast and play significant roles in plant defense, photosynthesis, and various molecular regulatory processes.

Comparative proteomic investigation of drought responses in foxtail millet

BackgroundFoxtail millet (Setaria italica L. P. Beauv) has been considered as a tractable model crop in recent years due to its short growing cycle, lower amount of repetitive DNA, inbreeding nature, small diploid genome, and outstanding abiotic stress-tolerance characteristics. With modern agriculture facing various adversities, it’s urgent to dissect the mechanisms of how foxtail millet responds and adapts to drought and stress on the proteomic-level.ResultsIn this research, a total of 2474 differentially expressed proteins were identified by quantitative proteomic analysis after subjecting foxtail millet seedlings to drought conditions. 321 of these 2474 proteins exhibited significant expression changes, including 252 up-regulated proteins and 69 down-regulated proteins. The resulting proteins could then be divided into different categories, such as stress and defense responses, photosynthesis, carbon metabolism, ROS scavenging, protein synthesis, etc., according to Gene Ontology annotation. Proteins implicated in fatty acid and amino acid metabolism, polyamine biosynthesis, hormone metabolism, and cell wall modifications were also identified. These obtained differential proteins and their possible biological functions under drought stress all suggested that various physiological and metabolic processes might function cooperatively to configure a new dynamic homeostasis in organisms. The expression patterns of five drought-responsive proteins were further validated using western blot analysis. The qRT-PCR was also carried out to analyze the transcription levels of 21 differentially expressed proteins. The results showed large inconsistency in the variation between proteins and the corresponding mRNAs, which showed once again that post-transcriptional modification performs crucial roles in regulating gene expression.ConclusionThe results offered a valuable inventory of proteins that may be involved in drought response and adaption, and provided a regulatory network of different metabolic pathways under stress stimulation. This study will illuminate the stress tolerance mechanisms of foxtail millet, and shed some light on crop germplasm breeding and innovation.