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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. [ABSTRACT FROM AUTHOR]

NAC (NAM, ATAF, CUC) is a class of transcription factors involved in plant growth regulation, abiotic stress responses, morphogenesis and metabolism. Salvia miltiorrhiza is an important Chinese medicinal herb, but the characterization of NAC genes in this species is limited. In this study, based on the Salvia miltiorrhiza genomic databases, 82 NAC transcription factors were identified, which were divided into 14 groups. Meanwhile, phylogenetic analysis, gene structure, chromosomal localization and potential role of SmNACs in abiotic stress conditions were also studied. The results revealed that some SmNACs had different structures than others, which advised that these genes may have multiple/distinct functions. Real-time quantitative polymerase chain reaction (RT-qPCR) analysis showed that SmNACs exhibited differential expression patterns under salt and drought stress. The NaCl induced salinity treatments modulated the expression of several SmNAC genes more in roots compared with leaves. Conversely, under drought stress conditions, more genes were upregulated in leaves compared with roots. These results will be useful for the further study involved in the functional characteristics of SmNAC genes, especially in response to salt and drought stresses, thereby may facilitate genetic breeding in Salvia miltiorrhiza. [ABSTRACT FROM AUTHOR]

Protoplast transient expression is a powerful strategy for gene functional characterization, especially in biochemical mechanism studies. We herein developed a highly efficient transient expression system for apple protoplasts. The abilities of the Arabidopsis thaliana and Malus domestica ubiquitin-10 (AtUBQ10 and MdUBQ10) promoters to drive the expression of multiple genes were compared with that of the CaMV 35S promoter, and the results revealed that the AtUBQ10 and MdUBQ10 promoters were more efficient in apple protoplasts. With this system, we demonstrated that active AtMKK7ac could activate MAPK6/3/4 signaling cascades, which further regulated MdWRKY33 phosphorylation and stability in apple. Furthermore, the ligand-induced interaction between the immune receptor AtFLS2 and the coreceptor AtBAK1 was reconstituted in apple protoplasts. We also found that the stability of the bacterial effector AvrRpt2 was regulated by feedback involving auxin and the immune regulator RIN4. The system established herein will serve as a useful tool for the molecular and biochemical analyses of apple genes. [ABSTRACT FROM AUTHOR]

Heat stress is an environmental challenge that reduces plant productivity and growth. Plants have developed corresponding mechanisms to survive this adverse environmental stress. To demonstrate the mechanisms of how plants adapt to the environmental challenge, the heat response experiments involving Arabidopsis thaliana were retrieved from the GEO database. After quantile normalization of the GEO raw data, the differentially expressed genes (DEGs) in response to heat stress were identified by robust rank aggregation (RRA) algorithm, including 384 up-regulated and 302 down-regulated genes. Then, systematic bioinformatics analyses disclosed that the up-regulated DEGs were mainly related to protein refolding, abscisic acid catabolic process, potassium ion import, response to hydrogen peroxide, cytochrome complex assembly, and apoptotic process, and the down-regulated DEGs were involved in microsporocyte differentiation, syncytium formation, adventitious development, glutathione metabolism, and glycine metabolic process. The up-regulated DEGs also had more complicated PPI interactions than the down-regulated DEGs, and potential core genes of heat stress tolerance were provided. Furthermore, the mRNA expression of core genes Hsp70-2 (At5g02490), Hsp70-3 (At3g09440), and Hsp70-4 (At3g12580) has been measured to validate the outcome of integrated bioinformatics analysis. Our work will extend our understanding of heat-responsive mechanisms and these DEGs might be potential markers for plant heat stress-resistance studies.