Genome-Wide Analysis of the DUF4228 Family in Soybean and Functional Identification of GmDUF4228 -70 in Response to Drought and Salt Stresses.

Domain of unknown function 4228 (DUF4228) proteins are a class of proteins widely found in plants, playing an important role in response to abiotic stresses. However, studies on the DUF4228 family in soybean (Glycine max L.) are sparse. In this study, we identified a total of 81 DUF4228 genes in soybean genome, named systematically based on their chromosome distributions. Results showed that these genes were unevenly distributed on the 20 chromosomes of soybean. The predicted soybean DUF4228 proteins were identified in three groups (Groups I-III) based on a maximum likelihood phylogenetic tree. Genetic structure analysis showed that most of the GmDUF4228 genes contained no introns. Expression profiling showed that GmDUF4228 genes were widely expressed in different organs and tissues in soybean. RNA-seq data were used to characterize the expression profiles of GmDUF4228 genes under the treatments of drought and salt stresses, with nine genes showing significant up-regulation under both drought and salt stress further functionally verified by promoter (cis-acting elements) analysis and quantitative real-time PCR (qRT-PCR). Due to its upregulation under drought and salt stresses based on both RNA-seq and qRT-PCR analyses, GmDUF4228-70 was selected for further functional analysis in transgenic plants. Under drought stress, the degree of leaf curling and wilting of the GmDUF4228-70-overexpressing (GmDUF4228-70-OE) line was lower than that of the empty vector (EV) line. GmDUF4228-70-OE lines also showed increased proline content, relative water content (RWC), and chlorophyll content, and decreased contents of malondialdehyde (MDA), H2O2, and O2-. Under salt stress, the changes in phenotypic and physiological indicators of transgenic plants were the same as those under drought stress. In addition, overexpression of the GmDUF4228-70 gene promoted the expression of marker genes under both drought and salt stresses. Taken together, the results indicated that GmDUF4228 genes play important roles in response to abiotic stresses in soybean.

Genomic Analysis of Stress Associated Proteins in Soybean and the Role of GmSAP16 in Abiotic Stress Responses in Arabidopsis and Soybean.

Stress associated proteins (SAPs) containing A20/AN1 zinc finger domains have emerged as novel regulators of stress responses. In this study, 27 SAP genes were identified in soybean. The phylogenetic relationships, exon-intron structure, domain structure, chromosomal localization, putative cis-acting elements, and expression patterns of SAPs in various tissues under abiotic stresses were analyzed. Among the soybean SAP genes, GmSAP16 was significantly induced by water deficit stress, salt, and abscisic acid (ABA) and selected for further analysis. GmSAP16 was located in the nucleus and cytoplasm. The overexpression of GmSAP16 in Arabidopsis improved drought and salt tolerance at different developmental stages and increased ABA sensitivity, as indicated by delayed seed germination and stomatal closure. The GmSAP16 transgenic Arabidopsis plants had a higher proline content and a lower water loss rate and malondialdehyde (MDA) content than wild type (WT) plants in response to stresses. The overexpression of GmSAP16 in soybean hairy roots enhanced drought and salt tolerance of soybean seedlings, with higher proline and chlorophyll contents and a lower MDA content than WT. RNA inference (RNAi) of GmSAP16 increased stress sensitivity. Stress-related genes, including GmDREB1B;1, GmNCED3, GmRD22, GmDREB2, GmNHX1, and GmSOS1, showed significant expression alterations in GmSAP16-overexpressing and RNAi plants under stress treatments. These results indicate that soybean SAP genes play important roles in abiotic stress responses.

Genome-Wide Characterization and Expression Analysis of Soybean TGA Transcription Factors Identified a Novel TGA Gene Involved in Drought and Salt Tolerance.

The TGA transcription factors, a subfamily of bZIP group D, play crucial roles in various biological processes, including the regulation of growth and development as well as responses to pathogens and abiotic stress. In this study, 27 TGA genes were identified in the soybean genome. The expression patterns of GmTGA genes showed that several GmTGA genes are differentially expressed under drought and salt stress conditions. Among them, GmTGA17 was strongly induced by both stress, which were verificated by the promoter-GUS fusion assay. GmTGA17 encodes a nuclear-localized protein with transcriptional activation activity. Heterologous and homologous overexpression of GmTGA17 enhanced tolerance to drought and salt stress in both transgeinc Arabidopsis plants and soybean hairy roots. However, RNAi hairy roots silenced for GmTGA17 exhibited an increased sensitivity to drought and salt stress. In response to drought or salt stress, transgenic Arabidopsis plants had an increased chlorophyll and proline contents, a higher ABA content, a decreased MDA content, a reduced water loss rate, and an altered expression of ABA- responsive marker genes compared with WT plants. In addition, transgenic Arabidopsis plants were more sensitive to ABA in stomatal closure. Similarly, measurement of physiological parameters showed an increase in chlorophyll and proline contents, with a decrease in MDA content in soybean seedlings with overexpression hairy roots after drought and salt stress treatments. The opposite results for each measurement were observed in RNAi lines. This study provides new insights for functional analysis of soybean TGA transcription factors in abiotic stress.

Genome-wide analysis of the YABBY family in soybean and functional identification of GmYABBY10 involvement in high salt and drought stresses.

YABBY family is a plant specific transcription factor family, with the typical N-terminal C2C2 type zinc finger domain and the C-terminal YABBY conservative structure domain, which plays important biological roles in plant growth, development and morphogenesis. In this study, a total of 17 YABBY genes were identified in the soybean genome. The results of this research showed that 17 soybean YABBY genes were located on 11 chromosomes. Analysis of putative cis-acting elements showed that soybean YABBY genes contained lots of MYB and MYC elements. Quantitative Real-time PCR (qRT-PCR) showed that the expressions of GmYABBY3, GmYABBY10 and GmYABBY16 were more highly sensitive in drought, NaCl and ABA stresses. And the transient expression in Arabidopsis protoplasts showed that GmYABBY3 protein distributed uniformly the whole cells, while GmYABBY10 protein was mainly localized in the membranes and cytoplasm and GmYABBY16 protein was localized the nucleus and membranes. To further identify the function of GmYABBY10, we obtained the transgenic Arabidopsis overexpression GmYABBY10. Based on germination and seedling root arrays in transgenic Arabidopsis, we found that the rates of wild type seeds was a litter higher than that of GmYABBY10 transgenic seeds under both PEG and NaCl treatment. While the root length and root surface of wild type seedlings were bigger than those of GmYABBY10 transgenic seedlings. When seedlings were grown in soil, the survival rates of wild type were higher than those of transgenic plants under both PEG and NaCl treatment, which indicated that GmYABBY10 may be a negatively regulator in plant resistances to drought and salt stresses. This study provided valuable information regarding the classification and functions of YABBY genes in soybean.

The soybean GmDi19-5 interacts with GmLEA3.1 and increases sensitivity of transgenic plants to abiotic stresses.

Drought-induced (Di19) proteins played important roles in plant growth, development, and abiotic stress responses. In the present study, a total of seven Di19 genes were identified in soybean. Each soybean Di19 gene showed specific responses to salt, drought, oxidative, and ABA stresses based on expression profiles. With a relatively higher transcript level among Di19 members under four stress treatments, GmDi19-5 was selected for detailed analysis. Inhibitor assays revealed that ABA inhibitor (Fluridone) or H2O2 inhibitor (DMTU) was involved in the drought- or salt-induced transcription of GmDi19-5. The GUS activity driven by the GmDi19-5 promoter was induced by salt, PEG, ABA, and MV treatments and tended to be accumulated in the vascular bundles and young leaves. A subcellular localization assay showed that GmDi19-5 protein localized in the nucleus. Further investigation showed that GmDi19-5 protein was involved in the interaction with GmLEA3.1. Overexpression of GmDi19-5 increased sensitivity of transgenic Arabidopsis plants to salt, drought, oxidative, and ABA stresses and regulated expression of several ABA/stress-associated genes. This present investigation showed that GmDi19-5 functioned as a negative factor under abiotic stresses and was involved in ABA and SOS signaling pathway by altering transcription of stress-associated genes.

[Monthly dynamics and distribution of major cations in Iris lactea].

The study on the monthly absorption, transportation, and distribution of Na+, K+, Ca2+ and Mg2+ in Iris lactea under saline-alkali field conditions showed that the contents of test cations in I. lactea varied with months. After June, the cations contents in plant increased with growth. Root Ca2+ and Na+ contents were the highest in July, being 2.30% and 0.51%, respectively, while root K+ and Mg2+ contents were the highest in September (0.27%) and October (0.28%), respectively. Leaf Na+ content was the highest in July (0.57%), while leaf K+, Ca2+ and Mg2+ contents were the highest in August, being 1.30%, 2.69% and 0.47%, respectively. In July and August, the selective absorption (SA) of K+ was higher than that of Na+, while the selective transport (ST) was in adverse. The cations contents in I. lactea were significantly higher than those in soil, suggesting that I. lactea had high accumulation capacity to these cations. The cations were mainly accumulated in the 0-30 cm aboveground part and 0-40 cm underground part of I. lactea, and the average contents of Na+, K+, Ca2+ and Mg2+ in aboveground part were 9.11, 4.07, 0.98 and 2.27 times of those in underground part, respectively.