Genome-wide identification of salinity responsive HSP70s in common bean

Comparative transcriptomic and proteomic analyses of two salt-tolerant alfalfa (Medicago sativa L.) genotypes: investigation of the mechanisms underlying tolerance to salt

Abiotic stressors such as salt stress restrict plant development and output, which lowers agricultural profitability. In this study, alfalfa (Medicago sativa L.) varieties with different levels of salt tolerance were examined using high-throughput RNA sequencing (RNA-Seq) and Tandem Mass Tags (TMT) technologies to study the reactions of the root systems to salt stress, from transcriptomics and proteomics perspectives. The varieties Atlantic (AT) and Zhongmu-1 (ZM-1) were selected and evaluated after 2 h and 6 h of treatment with 150 mM NaCl. The results showed that under salt stress for 2 h, 1810 differentially expressed genes (DEGs) and 160 differentially expressed proteins (DEPs) in AT were screened, while 9341 DEGs and 193 DEPs were screened in ZM-1. Under salt stress for 6 h, 7536 DEGs and 118 DEPs were screened in AT, while 11,754 DEGs and 190 DEPs were screened in ZM-1. Functional annotation and pathway enrichment analyses indicated that the DEGS and DEPs were mainly involved in the glutathione metabolism, biosynthesis of secondary metabolites, glycolysis/gluconeogenesis, carbon fixation in photosynthetic organisms, and photosynthesis pathways. A series of genes related to salt tolerance were also identified, including GSTL3 and GSTU3 of the GST gene family, PER5 and PER10, of the PER gene family, and proteins such as APR and COMT, which are involved in biosynthesis of secondary metabolites. This study provides insights into salt resistance mechanisms in plants, and the related genes and metabolic pathways identified may be helpful for alfalfa breeding in the future.

Comparative genome-wide characterization of salt responsive micro RNA and their targets through integrated small RNA and de novo transcriptome profiling in sugarcane and its wild relative Erianthus arundinaceus

Soil salinity and saline irrigation water are major constraints in sugarcane affecting the production of cane and sugar yield. To understand the salinity induced responses and to identify novel genomic resources, integrated de novo transcriptome and small RNA sequencing in sugarcane wild relative, Erianthus arundinaceus salt tolerant accession IND 99-907 and salt-sensitive sugarcane genotype Co 97010 were performed. A total of 362 known miRNAs belonging to 62 families and 353 miRNAs belonging to 63 families were abundant in IND 99-907 and Co 97010 respectively. The miRNA families such as miR156, miR160, miR166, miR167, miR169, miR171, miR395, miR399, miR437 and miR5568 were the most abundant with more than ten members in both genotypes. The differential expression analysis of miRNA reveals that 221 known miRNAs belonging to 48 families and 130 known miRNAs belonging to 42 families were differentially expressed in IND 99-907 and Co 97010 respectively. A total of 12,693 and 7982 miRNA targets against the monoploid mosaic genome and a total of 15,031 and 12,152 miRNA targets against the de novo transcriptome were identified for differentially expressed known miRNAs of IND 99-907 and Co 97010 respectively. The gene ontology (GO) enrichment analysis of the miRNA targets revealed that 24, 12 and 14 enriched GO terms (FDR < 0.05) for biological process, molecular function and cellular component respectively. These miRNAs have many targets that associated in regulation of biotic and abiotic stresses. Thus, the genomic resources generated through this study are useful for sugarcane crop improvement through biotechnological and advanced breeding approaches.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-023-03867-7.

Comprehensive investigation of cucumber heat shock proteins under abiotic stress conditions: A multi-omics survey

Heat-shock proteins (Hsps) are a family of proteins essential in preserving the vitality and functionality of proteins under stress conditions. Cucumber (Cucumis sativus) is a widely grown plant with high nutritional value and is used as a model organism in many studies. This study employed a genomics, transcriptomics, and metabolomics approach to investigate cucumbers' Hsps against abiotic stress conditions. Bioinformatics methods were used to identify six Hsp families in the cucumber genome and to characterize family members. Transcriptomics data from the Sequence Read Archive (SRA) database was also conducted to select CsHsp genes for further study. Real-time PCR was used to evaluate gene expression levels under different stress conditions, revealing that CssHsp-08 was a vital gene for resistance to stress conditions; including drought, salinity, cold, heat stresses, and ABA application. Gas Chromatography-Mass Spectrometry (GC-MS) analysis of plant extracts revealed that amino acids accumulate in leaves under high temperatures and roots under drought, while sucrose accumulates in both tissues under applied most stress factors. The study provides valuable insights into the structure, organization, evolution, and expression profiles of the Hsp family and contributes to a better understanding of plant stress mechanisms. These findings have important implications for developing crops that can withstand environmental stress conditions better.

Salt stress responses and alleviation strategies in legumes: a review of the current knowledge

Salinity is one of the most significant environmental factors limiting legumes development and productivity. Salt stress disturbs all developmental stages of legumes and affects their hormonal regulation, photosynthesis and biological nitrogen fixation, causing nutritional imbalance, plant growth inhibition and yield losses. At the molecular level, salt stress exposure involves large number of factors that are implicated in stress perception, transduction, and regulation of salt responsive genes' expression through the intervention of transcription factors. Along with the complex gene network, epigenetic regulation mediated by non-coding RNAs, and DNA methylation events are also involved in legumes' response to salinity. Different alleviation strategies can increase salt tolerance in legume plants. The most promising ones are Plant Growth Promoting Rhizobia, Arbuscular Mycorrhizal Fungi, seed and plant's priming. Genetic manipulation offers an effective approach for improving salt tolerance. In this review, we present a detailed overview of the adverse effect of salt stress on legumes and their molecular responses. We also provide an overview of various ameliorative strategies that have been implemented to mitigate/overcome the harmful effects of salt stress on legumes.

Characterization of HSP70 family in watermelon (Citrullus lanatus): identification, structure, evolution, and potential function in response to ABA, cold and drought stress

Watermelon (Citrullus lanatus) as a crop with important economic value, is widely cultivated around the world. The heat shock protein 70 (HSP70) family in plant is indispensable under stress conditions. However, no comprehensive analysis of watermelon HSP70 family is reported to date. In this study, 12 ClHSP70 genes were identified from watermelon, which were unevenly located in 7 out of 11 chromosomes and divided into three subfamilies. ClHSP70 proteins were predicted to be localized primarily in cytoplasm, chloroplast, and endoplasmic reticulum. Two pairs of segmental repeats and 1 pair of tandem repeats existed in ClHSP70 genes, and ClHSP70s underwent strong purification selection. There were many abscisic acid (ABA) and abiotic stress response elements in ClHSP70 promoters. Additionally, the transcriptional levels of ClHSP70s in roots, stems, true leaves, and cotyledons were also analyzed. Some of ClHSP70 genes were also strongly induced by ABA. Furthermore, ClHSP70s also had different degrees of response to drought and cold stress. The above data indicate that ClHSP70s may be participated in growth and development, signal transduction and abiotic stress response, laying a foundation for further analysis of the function of ClHSP70s in biological processes.

Genome-wide identification of NHX (Na+/H+ antiporter) gene family in Cucurbita L. and functional analysis of CmoNHX1 under salt stress

Soil salinization, which is the accumulation of salt in soil, can have a negative impact on crop growth and development by creating an osmotic stress that can reduce water uptake and cause ion toxicity. The NHX gene family plays an important role in plant response to salt stress by encoding for Na⁺/H⁺ antiporters that help regulate the transport of sodium ions across cellular membranes. In this study, we identified 26 NHX genes in three cultivars of Cucurbita L., including 9 Cucurbita moschata NHXs (CmoNHX1-CmoNHX9), 9 Cucurbita maxima NHXs (CmaNHX1-CmaNHX9) and 8 Cucurbita pepo NHXs (CpNHX1-CpNHX8). The evolutionary tree splits the 21 NHX genes into three subfamilies: the endosome (Endo) subfamily, the plasma membrane (PM) subfamily, and the vacuole (Vac) subfamily. All the NHX genes were irregularly distributed throughout the 21 chromosomes. 26 NHXs were examined for conserved motifs and intron-exon organization. These findings suggested that the genes in the same subfamily may have similar functions while genes in other subfamilies may have functional diversity. The circular phylogenetic tree and collinearity analysis of multi-species revealed that Cucurbita L. had a substantially greater homology relationship than Populus trichocarpa and Arabidopsis thaliana in terms of NHX gene homology. We initially examined the cis-acting elements of the 26 NHXs in order to investigate how they responded to salt stress. We discovered that the CmoNHX1, CmaNHX1, CpNHX1, CmoNHX5, CmaNHX5, and CpNHX5 all had numerous ABRE and G-box cis-acting elements that were important to salt stress. Previous transcriptome data showed that in the mesophyll and veins of leaves, many CmoNHXs and CmaNHXs, such as CmoNHX1, responded significantly to salt stress. In addition, we heterologously expressed in A. thaliana plants in order to further confirm the response of CmoNHX1 to salt stress. The findings demonstrated that during salt stress, A. thaliana that had CmoNHX1 heterologously expression was found to have decreased salt tolerance. This study offers important details that will aid in further elucidating the molecular mechanism of NHX under salt stress.

The genome-wide characterization of WOX gene family in Phaseolus vulgaris L. during salt stress

The WUSCHEL-Related Homeobox (WOX) family is a type of homeobox transcription factor superfamily and its members perform many functions ranging from plant embryonic growth to organ formation in plants. Although the WOX proteins have been identified and characterized in many plant species, genome-wide identification and characterization of WOX proteins in the Phaseolus vulgaris genome has been performed for the first time in this study. Accordingly, 18 WOX proteins were identified using bioinformatics tools and biochemical/physicochemical properties of these proteins were investigated. Phvul-WOX genes were found to be categorized into three major phylogenetic groups according to the phylogenetic analysis and a total of five segmental duplication events were detected after duplication analysis. Moreover, the Phvul-WOX genes were found to be expressed in different plant tissues at different levels and some stress-related miRNAs have been found to target the Phvul-WOX genes based on miRNA analysis. Additionaly, MDA content, total protein level and catalase enzyme activity analyses were conducted in two P. vulgaris cultivars namely Yakutiye cv. and Zulbiye cv. subjected to 150 mM salt stress. Next, these cultivars were used for screening the expression levels of Phvul-WOX-1, Phvul-WOX-9, Phvul-WOX-11, Phvul-WOX-15 and Phvul-WOX-16 genes in response to salt stress. The insights gained from this study may be of assistance to the researchers who work in this area.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12298-022-01208-1.

Identification and Characterization of SRS Genes in Phaseolus vulgaris Genome and Their Responses Under Salt Stress

SHI-Related Sequence (SRS) transcription factors comprise a protein family with important roles in growth and development. However, the genome-wide study of the SRS protein family has not yet been carried out in the common bean. For this reason, the SRS family has been characterized in depth at both gene and protein levels and several bioinformatics methods have been used. As a result, 10 SRS genes have been identified and their proteins have been phylogenetically categorized into three major groups within the common bean. By investigating duplications that play a major role in the development of gene families, 19 duplication events have been identified in the SRS family (18 segmental and 1 tandem). In addition, using available RNAseq data, comparative expression analysis of Pvul-SRS genes was performed and expression changes in Pvul-SRS-1, 2, 4, 6, 7, and 10 genes were observed under both salt and drought stress. Five Pvul-SRS genes were selected based on RNAseq data (Pvul-SRS-1, 2, 4, 6, and 10) and screened with RT-qPCR in two common bean cultivars (Yakutiye 'salt-resistant' and Zulbiye 'salt-susceptible' cv.). These genes also showed different levels of expression between two common bean cultivars under salt stress conditions and this may explain the responses of Pvul-SRS genes against abiotic stress. In summary, this work is the first study in which in silico identification and characterization of Pvul-SRS genes have been examined at gene expression level. The results could therefore provide the basis for future studies of functional characterization of Pvul-SRS genes.

Genome-Wide Characterization and Expression Analysis of CAMTA Gene Family Under Salt Stress in Cucurbita moschata and Cucurbita maxima

Cucurbita Linn. vegetables have a long history of cultivation and have been cultivated all over the world. With the increasing area of saline–alkali soil, Cucurbita Linn. is affected by salt stress, and calmodulin-binding transcription activator (CAMTA) is known for its important biological functions. Although the CAMTA gene family has been identified in several species, there is no comprehensive analysis on Cucurbita species. In this study, we analyzed the genome of Cucurbita maxima and Cucurbita moschata. Five C. moschata calmodulin-binding transcription activators (CmoCAMTAs) and six C. maxima calmodulin-binding transcription activators (CmaCAMTAs) were identified, and they were divided into three subfamilies (Subfamilies I, II, and III) based on the sequence identity of amino acids. CAMTAs from the same subfamily usually have similar exon–intron distribution and conserved domains (CG-1, TIG, IQ, and Ank_2). Chromosome localization analysis showed that CmoCAMTAs and CmaCAMTAs were unevenly distributed across four and five out of 21 chromosomes, respectively. There were a total of three duplicate gene pairs, and all of which had experienced segmental duplication events. The transcriptional profiles of CmoCAMTAs and CmaCAMTAs in roots, stems, leaves, and fruits showed that these CAMTAs have tissue specificity. Cis-acting elements analysis showed that most of CmoCAMTAs and CmaCAMTAs responded to salt stress. By analyzing the transcriptional profiles of CmoCAMTAs and CmaCAMTAs under salt stress, it was shown that both C. moschata and C. maxima shared similarities against salt tolerance and that it is likely to contribute to the development of these species. Finally, quantitative real-time polymerase chain reaction (qRT-PCR) further demonstrated the key role of CmoCAMTAs and CmaCAMTAs under salt stress. This study provided a theoretical basis for studying the function and mechanism of CAMTAs in Cucurbita Linn.

Genome-wide identification and phylogenetic relationships of the Hsp70 gene family of Aegilops tauschii, wild emmer wheat (Triticum dicoccoides) and bread wheat (Triticum aestivum)

Heat shock protein 70 (Hsp70) plays an important role in plant development. It is closely related to the physiological process of cell development and the response to abiotic and biological stress. However, the classification and evolution of Hsp70 genes in bread wheat, wild emmer wheat and Aegilops tauschii are still unclear. Therefore, this study conducted a comprehensive bioinformatics analysis of Hsp70 gene in three species. Among these three species, 113, 79 and 36 Hsp70 genes were identified. They are divided into six subfamilies. Group vi-1 is different from Arabidopsis thaliana. It may be the result of early evolutionary segregation. The number of exons in different subfamilies (from 1 to 13) was different, but the distribution patterns of exons / introns in the same subfamily were similar. The results of Hsp70 promoter region analysis showed that the cis-regulatory elements of A. tauschii and wild emmer wheat were different from those of wheat. In addition, CpG island proportion of wild emmer Hsp70 was higher than that of wheat, which may be the molecular basis of heat resistance of wild wheat relative to cultivated wheat. Further comprehensive analysis of chromosome location and repeat events of Hsp70 gene showed that whole-genome duplication and tandem duplication events contributed to the evolution and expansion of Hsp70 gene in wheat. The results of non-synonymous substitution and synonymous substitution analysis showed that Hsp70 genes of three species had undergone purification selection. The expression profile analysis showed that Hsp70 gene was highly expressed in the roots during the vegetative growth period. In addition, TaHsp70 gene was highly expressed under various stress. The identification, classification and evolution of Hsp70 in wheat and its relatives provided a basis for further research on its evolution and its molecular mechanism in response to stress.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s13205-021-02639-5.

StCaM2, a calcium binding protein, alleviates negative effects of salinity and drought stress in tobacco

KEY MESSAGE

Overexpression of StCaM2 in tobacco promotes plant growth and confers increased salinity and drought tolerance by enhancing the photosynthetic efficiency, ROS scavenging, and recovery from membrane injury. Calmodulins (CaMs) are important Ca2+ sensors that interact with effector proteins and drive a network of signal transduction pathways involved in regulating the growth and developmental pattern of plants under stress. Herein, using in silico analysis, we identified 17 CaM isoforms (StCaM) in potato. Expression profiling revealed different temporal and spatial expression patterns of these genes, which were modulated under abiotic stress. Among the identified StCaM genes, StCaM2 was found to have the largest number of abiotic stress responsive promoter elements. In addition, StCaM2 was upregulated in response to some of the selected abiotic stress in potato tissues. Overexpression of StCaM2 in transgenic tobacco plants enhanced their tolerance to salinity and drought stress. Accumulation of reactive oxygen species was remarkably decreased in transgenic lines compared to that in wild type plants. Chlorophyll a fluorescence analysis suggested better performance of photosystem II in transgenic plants under stress compared to that in wild type plants. The increase in salinity stress tolerance in StCaM2-overexpressing plants was also associated with a favorable K+/Na+ ratio. The enhanced tolerance to abiotic stresses correlated with the increase in the activities of anti-oxidative enzymes in transgenic tobacco plants. Overall, our results suggest that StCaM2 can be a novel candidate for conferring salt and drought tolerance in plants.

Understanding salt tolerance mechanism using transcriptome profiling and de novo assembly of wild tomato Solanum chilense

Soil salinity affects the plant growth and productivity detrimentally, but Solanum chilense, a wild relative of cultivated tomato (Solanum lycopersicum L.), is known to have exceptional salt tolerance. It has precise adaptations against direct exposure to salt stress conditions. Hence, a better understanding of the mechanism to salinity stress tolerance by S. chilense can be accomplished by comprehensive gene expression studies. In this study 1-month-old seedlings of S. chilense and S. lycopersicum were subjected to salinity stress through application of sodium chloride (NaCl) solution. Through RNA-sequencing here we have studied the differences in the gene expression patterns. A total of 386 million clean reads were obtained through RNAseq analysis using the Illumina HiSeq 2000 platform. Clean reads were further assembled de novo into a transcriptome dataset comprising of 514,747 unigenes with N50 length of 578 bp and were further aligned to the public databases. Genebank non-redundant (Nr), Viridiplantae, Gene Ontology (GO), KOG, and KEGG databases classification suggested enrichment of these unigenes in 30 GO categories, 26 KOG, and 127 pathways, respectively. Out of 265,158 genes that were differentially expressed in response to salt treatment, 134,566 and 130,592 genes were significantly up and down-regulated, respectively. Upon placing all the differentially expressed genes (DEG) in known signaling pathways, it was evident that most of the DEGs involved in cytokinin, ethylene, auxin, abscisic acid, gibberellin, and Ca²⁺ mediated signaling pathways were up-regulated. Furthermore, GO enrichment analysis was performed using REVIGO and up-regulation of multiple genes involved in various biological processes in chilense under salinity were identified. Through pathway analysis of DEGs, “Wnt signaling pathway” was identified as a novel pathway for the response to the salinity stress. Moreover, key genes for salinity tolerance, such as genes encoding proline and arginine metabolism, ROS scavenging system, transporters, osmotic regulation, defense and stress response, homeostasis and transcription factors were not only salt-induced but also showed higher expression in S. chilense as compared to S. lycopersicum. Thus indicating that these genes may have an important role in salinity tolerance in S. chilense. Overall, the results of this study improve our understanding on possible molecular mechanisms underlying salt tolerance in plants in general and tomato in particular.

Comparative Transcriptome Analysis Reveals Molecular Defensive Mechanism of Arachis hypogaea in Response to Salt Stress

Abiotic stresses comprise all nonliving factors, such as soil salinity, drought, extreme temperatures, and metal toxicity, posing a serious threat to agriculture and affecting the plant production around the world. Peanut (Arachis hypogaea L.) is one of the most important crops for vegetable oil, proteins, minerals, and vitamins in the world. Therefore, it is of importance to understand the molecular mechanism of peanut against salt stress. Six transcriptome sequencing libraries including 24-hour salt treatments and control samples were constructed from the young leaves of peanut. A comprehensive analysis between two groups detected 3,425 differentially expressed genes (DEGs) including 2,013 upregulated genes and 1,412 downregulated genes. Of these DEGs, 141 transcription factors (TFs) mainly consisting of MYB, AP2/ERF, WRKY, bHLH, and HSF were identified in response to salinity stress. Further, GO categories of the DEGs highly related to regulation of cell growth, cell periphery, sustained external encapsulating structure, cell wall organization or biogenesis, antioxidant activity, and peroxidase activity were significantly enriched for upregulated DEGs. The function of downregulated DEGs was mainly enriched in regulation of metabolic processes, oxidoreductase activity, and catalytic activity. Fourteen DEGs with response to salt tolerance were validated by real-time PCR. Taken together, the identification of DEGs' response to salt tolerance of cultivated peanut will provide a solid foundation for improving salt-tolerant peanut genetic manipulation in the future.

Genome-wide analysis of HSP70 family genes in cabbage (Brassica oleracea var. capitata) reveals their involvement in floral development

BACKGROUND

Heat shock proteins have important functions in regulating plant growth and response to abiotic stress. HSP70 family genes have been described in several plant species, but a comprehensive analysis of the HSP70 family genes in cabbage has not been reported to date, especially their roles in floral development.

RESULTS

In this study, we identified 52 BoHSP70 genes in cabbage. The gene structures, motifs, and chromosome locations of the BoHSP70 genes were analyzed. The genes were divided into seven classes using a phylogenetic analysis. An expression analysis showed that the BoHSP70 genes were highly expressed in actively growing tissues, including buds and calluses. In addition, six BoHSP70 genes were highly expressed in the binuclear-pollen-stage buds of a male fertile line compared with its near isogenic sterile line. These results were further verified using qRT-PCR. Subcellular localization analysis of the bud-specific gene BoHSP70-5 showed that it was localized in the cytoplasm.

CONCLUSIONS

Our results help to elucidate the involvement of the BoHSP70 family genes in cabbage floral development and establish the groundwork for future research on the functions of these genes.

Genome-wide identification of CAMTA gene family members in Phaseolus vulgaris L. and their expression profiling during salt stress

The calmodulin-binding transcriptional activator (CAMTA) family was first observed in tobacco (NtER1) during a screening for the CaM-binding proteins, which are known to be one of the fast response stress proteins. Due to the increased importance of plant transcription factors in recent years; genome-wide identification of CAMTA genes has been performed in several plant species, except for Phaseolus vulgaris. Therefore, our aim was to identify and characterize CAMTA genes in P. vulgaris via in silico genome-wide analysis approach. Our results showed a total of eight CAMTA genes that were identified and observed on five out of 11 chromosomes of P. vulgaris. Four gene couples were found to be segmentally-duplicated and these segmental duplication events were shown to occur from 29.97 to 92.06 MYA. The phylogenetic tree of CAMTA homologs from P. vulgaris, A. thaliana, and G. max. revealed three groups based on their homology and the intron numbers of Pvul-CAMTA genes, ranged from 11 to 12. According to the syteny analysis; CAMTA genes of P. vulgaris and G. max revealed higher similarity, because they have highly similar genomes compared to A. thaliana. All Pvul-CAMTA genes were targeted by miRNAs, which play a role in response mechanism of salt stress. To detect expression levels in different plant tissues, mRNA analysis of Pvul-CAMTA genes were performed using publicly available expression data in Phytozome v12.1. In addition, responses of Pvul-CAMTA genes to salt stress, were also examined via both RNAseq and qRT-PCR analysis. To identify and to obtain insight into biological functions of CAMTA genes in the genome of P. vulgaris, several analyses were conducted using many online and offline bioinformatic tools, genome databases and qRT-PCR analyses. Due to this study being the first in the identification of CAMTA genes in P. vulgaris, this study could be considered as an useful source for future CAMTA genes studies in either P. vulgaris or comparative different plant species.

Salinity stress response and 'omics' approaches for improving salinity stress tolerance in major grain legumes

Sustaining yield gains of grain legume crops under growing salt-stressed conditions demands a thorough understanding of plant salinity response and more efficient breeding techniques that effectively integrate modern omics knowledge. Grain legume crops are important to global food security being an affordable source of dietary protein and essential mineral nutrients to human population, especially in the developing countries. The global productivity of grain legume crops is severely challenged by the salinity stress particularly in the face of changing climates coupled with injudicious use of irrigation water and improper agricultural land management. Plants adapt to sustain under salinity-challenged conditions through evoking complex molecular mechanisms. Elucidating the underlying complex mechanisms remains pivotal to our knowledge about plant salinity response. Improving salinity tolerance of plants demand enriching cultivated gene pool of grain legume crops through capitalizing on 'adaptive traits' that contribute to salinity stress tolerance. Here, we review the current progress in understanding the genetic makeup of salinity tolerance and highlight the role of germplasm resources and omics advances in improving salt tolerance of grain legumes. In parallel, scope of next generation phenotyping platforms that efficiently bridge the phenotyping-genotyping gap and latest research advances including epigenetics is also discussed in context to salt stress tolerance. Breeding salt-tolerant cultivars of grain legumes will require an integrated "omics-assisted" approach enabling accelerated improvement of salt-tolerance traits in crop breeding programs.

Transcriptome profiling of a beach-adapted wild legume for dissecting novel mechanisms of salinity tolerance

Strophostyles helvola is a close relative to common bean (Phaseolus vulgaris) and inhabits both coastal and non-coastal regions in North America. However, the mechanism of saline adaptation in S. helvola remains unclear. A transcriptome profiling would facilitate dissecting the underlying molecular mechanisms in salinity-adapted S. helvola. In this study, we reported the RNA-seq analyses of two genotypes (a salt-tolerant beach genotype and a salt-sensitive inland genotype) of S. helvola stressed with salt. S. helvola plants were grown in pots and treated with half lethal-guided dose of NaCl solution for 3 h, 24 h, and 7d. The plants supplied with the same amount of water were used as controls. The whole roots sampled from the three time points were equally pooled as one biological replicate, and three replicates were used for library construction and transcriptome sequencing on Illumina Hiseq 2500. The comparative analyses of root transcriptomes presented here provides a valuable resource for discovery of genes and networks involved in salt tolerance in S. helvola.

Genome-wide analysis of Phaseolus vulgaris C2C2-YABBY transcription factors under salt stress conditions

The aim of this study was to identify and characterize the C2C2-YABBY family of genes by a genome-wide scale in common bean. Various in silico approaches were used for the study and the results were confirmed through common molecular biology techniques. Quantitative real-time PCR (qPCR) analysis was performed for identified putative PvulYABBY genes in leaf and root tissues of two common bean cultivars, namely Yakutiye and Zulbiye under salt stress condition. Eight candidate PvulYABBY proteins were discovered and the length of these proteins ranged from 173 to 256 amino acids. The isoelectric points (pIs) of YABBY proteins were between 5.18 and 9.34 and ranged from acidic to alkaline, and the molecular weight of PvulYABBYs were between 18978.4 and 28916.8 Da. Three segmentally duplicated gene couples among the identified eight PvulYABBY genes were detected. These segmentally duplicated gene couples were PvulYABBY-1/PvulYABBY-3, PvulYABBY-5/PvulYABBY-7 and PvulYABBY-6/PvulYABBY-8. The predicted number of exons among the PvulYABBY genes varied from 6 to 8 exons. Additionally, all genes found included introns within ORFs. PvulYABBY-2, -4, -5 and -7 genes were targeted by miRNAs of five plant species and a total of five miRNA families (miR5660, miR1157, miR5769, miR5286 and miR8120) were detected. According to RNA-seq analysis, all genes were up- or down-regulated except for PvulYABBY-1 and PvulYABBY-6 after salt stress treatment in leaf and root tissues of common bean. According to the qPCR analysis, six out of eight genes were expressed in the leaves but only four out of eight genes were expressed in the roots and these genes exhibited tissue- and cultivar-specific expression patterns.

RNAseq analysis reveals pathways and candidate genes associated with salinity tolerance in a spaceflight-induced wheat mutant

Salinity stress has become an increasing threat to food security worldwide and elucidation of the mechanism for salinity tolerance is of great significance. Induced mutation, especially spaceflight mutagenesis, is one important method for crop breeding. In this study, we show that a spaceflight-induced wheat mutant, named salinity tolerance 1 (st1), is a salinity-tolerant line. We report the characteristics of transcriptomic sequence variation induced by spaceflight, and show that mutations in genes associated with sodium ion transport may directly contribute to salinity tolerance in st1. Furthermore, GO and KEGG enrichment analysis of differentially expressed genes (DEGs) between salinity-treated st1 and wild type suggested that the homeostasis of oxidation-reduction process is important for salt tolerance in st1. Through KEGG pathway analysis, "Butanoate metabolism" was identified as a new pathway for salinity responses. Additionally, key genes for salinity tolerance, such as genes encoding arginine decarboxylase, polyamine oxidase, hormones-related, were not only salt-induced in st1 but also showed higher expression in salt-treated st1 compared with salt-treated WT, indicating that these genes may play important roles in salinity tolerance in st1. This study presents valuable genetic resources for studies on transcriptome variation caused by induced mutation and the identification of salt tolerance genes in crops.

RNAseq analysis reveals pathways and candidate genes associated with salinity tolerance in a spaceflight-induced wheat mutant

Salinity stress has become an increasing threat to food security worldwide and elucidation of the mechanism for salinity tolerance is of great significance. Induced mutation, especially spaceflight mutagenesis, is one important method for crop breeding. In this study, we show that a spaceflight-induced wheat mutant, named salinity tolerance 1 (st1), is a salinity-tolerant line. We report the characteristics of transcriptomic sequence variation induced by spaceflight, and show that mutations in genes associated with sodium ion transport may directly contribute to salinity tolerance in st1. Furthermore, GO and KEGG enrichment analysis of differentially expressed genes (DEGs) between salinity-treated st1 and wild type suggested that the homeostasis of oxidation-reduction process is important for salt tolerance in st1. Through KEGG pathway analysis, "Butanoate metabolism" was identified as a new pathway for salinity responses. Additionally, key genes for salinity tolerance, such as genes encoding arginine decarboxylase, polyamine oxidase, hormones-related, were not only salt-induced in st1 but also showed higher expression in salt-treated st1 compared with salt-treated WT, indicating that these genes may play important roles in salinity tolerance in st1. This study presents valuable genetic resources for studies on transcriptome variation caused by induced mutation and the identification of salt tolerance genes in crops.