Strigolactone signaling gene from soybean GmMAX2a enhances the drought and salt-alkaline resistance in Arabidopsis via regulating transcriptional profiles of stress-related genes.

Strigolactone (SL) is a new plant hormone, which not only plays an important role in stimulating seed germination, plant branching, and regulating root development, but also plays an important role in the response of plants to abiotic stresses. In this study, the full-length cDNA of a soybean SL signal transduction gene (GmMAX2a) was isolated, cloned and revealed an important role in abiotic stress responses. Tissue-specific expression analysis by qRT-PCR indicated that GmMAX2a was expressed in all tissues of soybean, but highest expression was detected in seedling stems. Moreover, upregulation of GmMAX2a transcript expression under salt, alkali, and drought conditions were noted at different time points in soybean leaves compared to roots. Additionally, histochemical GUS staining studies revealed the deep staining in PGmMAX2a: GUS transgenic lines compared to WT indicating active involvement of GmMAX2a promoter region to stress responses. To further investigate the function of GmMAX2a gene in transgenic Arabidopsis, Petri-plate experiments were performed and GmMAX2a OX lines appeared with longer roots and improved fresh biomass compared to WT plants to NaCl, NaHCO3, and mannitol supplementation. Furthermore, the expression of several stress-related genes such as RD29B, SOS1, NXH1, AtRD22, KIN1, COR15A, RD29A, COR47, H+-APase, NADP-ME, NCED3, and P5CS were significantly high in GmMAX2a OX plants after stress treatment compared to WT plants. In conclusion, GmMAX2a improves soybean tolerance towards abiotic stresses (salt, alkali, and drought). Hence, GmMAX2a can be considered a candidate gene for transgenic breeding against various abiotic stresses in plants.

[Identification of heat shock protein hsp70 family genes from Rana amurensis and its expression profiles upon infection].

Heat shock proteins (HSPs) widely exist in all organisms, the structures of which are usually extraordinarily conservative. They are also well-known stress proteins that are involved in response to physical, chemical and biological stresses. HSP70 is an important member of the HSPs family. In order to study the roles of amphibians HSP70 during infection, the cDNA sequence of Rana amurensis hsp70 family genes were cloned by homologous cloning method. The sequence characteristics, three-dimensional structure and genetic relationship of Ra-hsp70s were analyzed by bioinformatics methods. The expression profiles under bacterial infection were also analyzed by real-time quantitative PCR (qRT-PCR). Expression and localization of HSP70 protein were tested by immunohistochemical techniques. The results showed that three conservative tag sequences of HSP70 family, HSPA5, HSPA8 and HSPA13, were found in HSP70. Phylogenetic tree analysis indicated four members are distributed in four different branches, and members with the same subcellular localization motif are distributed in the same branch. The relative expression levels of the mRNA of four members were all significantly upregulated (P < 0.01) upon infection, but the time for up-regulating the expression levels were diverse in different tissues. The immunohistochemical analysis showed that HSP70 was expressed to different degrees in the cytoplasm of liver, kidney, skin and stomach tissue. The four members of Ra-hsp70 family have ability to respond bacterial infection to varying degrees. Therefore, it was proposed that they are involved in biological processes against pathogen and play different biological functions. The study provides a theoretical basis for functional studies of HSP70 gene in amphibians.

Exogenous strigolactones enhance tolerance in soybean seedlings in response to alkaline stress.

The plant hormone strigolactones (SLs) play crucial roles in regulating plant development and adaptations to abiotic stresses. Even though the functional roles of SLs have been identified in response to abiotic stresses, the function, and mechanism of SLs are not fully established under alkaline stress. In this study, we identified that exogenous SL could improve alkaline tolerance of soybean seedlings, especially when treated with 0.5 µM SL. The application of SL remarkably reduced the malondialdehyde content, hydrogen peroxide content, and increased the activity of antioxidant enzymes under alkaline stress, suggesting that SL improved the alkaline tolerance by regulating the antioxidant defense capacity. The RNA sequencing data showed 530 special differentially expressed genes under SL treatment and alkaline stress, mainly were associated with antioxidant processes and phenylpropanoid biosynthetic pathway. Some transcription factors were also induced by SL under alkaline stress as confirmed by quantitative real-time PCR (qRT-PCR). Furthermore, SL largely increased the Na content in leaves and decreased Na content in roots under alkaline stress, which suggested that SL might promote the transport of Na from the roots to the leaves of the soybean seedlings. Meanwhile, exogenous SL decreased the content of other elements such as K, Mg, Fe, and Cu in leaves or roots under alkaline stress. Collectively, our results suggested a role of SL in regulating antioxidant defense capacity, specific gene expression, and alterations in ionic contents to alleviate harmful effects of alkaline stress in soybean seedlings.

[Separation of protein and isoflavone in soybean whey by ultrafiltration].

The study on the technical conditions of separating protein and isoflavone in soybean whey by ultrafiltration showed that before ultrafiltration, soybean whey should be pretreated to reduce membrane contamination. The orthogonal experiment of 2 factors and 3 levels indicated that the optimum pretreatment conditions were 5% of CaCl, addition based on the solid substance content in soybean whey, and heating up at 85 degrees C for 15 minutes. Under these conditions, the precipitation rate of whey protein was 49. 8% , while the reservation rate of isoflavone was 90.4%. Single factor experiment showed that the optimum ultrafiltration conditions were poly (ether sulfone) membrane of 10 kDa molecular weight cut-off (MWCO), 51-68 kPa, and 30 degrees C-40 degrees C. Under these conditions, the retention rate of whey protein and isoflavone was 83.9% and 7.6% , respectively.