Abiotic stresses such as salinity and low temperature have serious impact on peanut growth and yield. The present work investigated the function of a MYB-related transcription factor gene AhMYB30 obtained from peanut under salt and low temperature stresses by transgenic methods. The results indicated that the overexpression of AhMYB30 in Arabidopsis could enhance the resistance of transgenic plants to freezing and salt stresses. The expression of stress-response genes RD29A (Response-to-Dehydration 29A), COR15A (Cold-Regulated 15A), KIN1 (Kinesin 1) and ABI2 (Abscisic acid Insensitive 2) increased in transgenic plants compared with in wild-type. Subcellular localization and transcriptional autoactivation validation demonstrated that AhMYB30 has essential features of transcription factors. Therefore, AhMYB30 may increase salt and freezing stress tolerance as the transcription factor (TF) in Arabidopsis through both DREB/CBF and ABA-signaling pathways. Our results lay the theoretical foundation for exploring stress resistance mechanisms of peanut and offering novel genetic resources for molecular breeding.

Soil sickness is the progressive loss of soil quality due to continuous monocropping. The bacterial populations are critical to sustaining agroecosystems, but their responses to long-term peanut monocropping have not been determined. In this study, based on a previously constructed gradient of continuous monocropped plots, we tracked the detailed feedback responses of soil bacteria to short- and long-term continuous monocropping of four different peanut varieties using high-throughput sequencing techniques. The analyses showed that soil samples from 1- and 2-year monocropped plots were grouped into one class, and samples from the 11- and 12-year plots were grouped into another. Long-term consecutive monocropping could lead to a general loss in bacterial diversity and remarkable changes in bacterial abundance and composition. At the genera level, the dominant genus Bacillus changed in average abundance from 1.49% in short-term monocropping libraries to 2.96% in the long-term libraries. The dominant species Bacillus aryabhattai and Bacillus funiculus and the relatively abundant species Bacillus luciferensis and Bacillus decolorationis all showed increased abundance with long-term monocropping. Additionally, several other taxa at the genus and species level also presented increased abundance with long-term peanut monocropping; however, several taxa showed decreased abundance. Comparing analyses of predicted bacterial community functions showed significant changes at different KEGG pathway levels with long-term peanut monocropping. Combined with our previous study, this study indicated that bacterial communities were obviously influenced by the monocropping period, but less influenced by peanut variety and growth stage. Some bacterial taxa with increased abundance have functions of promoting plant growth or degrading potential soil allelochemicals, and should be closely related with soil remediation and may have potential application to relieve peanut soil sickness. A decrease in diversity and abundance of bacterial communities, especially beneficial communities, and simplification of bacterial community function with long-term peanut monocropping could be the main cause of peanut soil sickness.

In search of efficient salt-tolerant phosphate solubilizing bacteria (PSB), we conducted a survey of PSB that naturally colonize the rhizosphere of peanuts in Xinjiang, China, a typical inland saline area. A total of 23 PSB were isolated, which included 12 Bacillus strains, three Acinetobacter strains, two Pseudomonas strains, two Brevibacillus, and one strain of Gordonia terrae, Chryseobacterium lathyri, Ensifer sesbaniae, and Paenibacillus illinoisensis. All PSB have high potential for dissolving calcium phosphate [Ca₃(PO₄)₂] within the range of 65–496 mg·L⁻¹, but relatively weak ability to dissolve AlPO₄ in amounts ranging from 0.4 to 11.4 mg·L⁻¹, FePO₄ ranging from 0.1 to 5.5 mg·L⁻¹, and lecithin ranging from 2.1 to 10.3 mg·L⁻¹. The maximum tolerance for pH is 10, and the maximum tolerance for Na₂CO₃ is 50 mm. Six isolates that can grow under the condition of 1.5 M NaCl (YMX5, YMX11, TPMX5, TPMX16, TPMX18, and TPMX19) were selected to determine their ability to dissolve Ca₃(PO₄)₂ and tolerate pH changes. This study characterized salt-tolerant PSB isolates that can be used as bioinoculants to protect plants against salt stress. In addition, we describe the phosphate-solubilizing ability of Gordonia terrae at high NaCl concentrations.