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Gelsemium elegans (G. elegans) is a Chinese medicinal plant with substantial economic and feeding values. There is a lack of detailed studies on the mitochondrial genome of G. elegans. In this study, the mitochondrial genome of G. elegans was sequenced and assembled, and its substructure was investigated. The mitochondrial genome of G. elegans is represented by two circular chromosomes of 406,009 bp in length with 33 annotated protein-coding genes, 15 tRNA genes, and three rRNA genes. We detected 145 pairs of repeats and found that four pairs of repeats could mediate the homologous recombination into one major conformation and five minor conformations, and the presence of conformations was verified by PCR amplification and Sanger sequencing. A total of 124 SSRs were identified in the G. elegans mitochondrial genome. The homologous segments between the chloroplast and mitochondrial genomes accounted for 5.85% of the mitochondrial genome. We also predicted 477 RNA potential editing sites and found that the nad4 gene was edited 38 times, which was the most frequent occurrence. Taken together, the mitochondrial genome of G. elegans was assembled and annotated. We gained a more comprehensive understanding on the genome of this medicinal plant, which is vital for its effective utilization and genetic improvement, especially for cytoplasmic male sterility breeding and evolution analysis in G. elegans. [ABSTRACT FROM AUTHOR] more...

Gelsemium elegans , a vine plant of Loganiaceae, has both medicinal and forage values. However, it is susceptible to low temperatures during growth. Exploring low temperature response genes is of great significance for cold resistance breeding of G . elegans . Ethylene response factors (ERFs) are the transcription factors of the AP2/ERF superfamily and play a crucial role in plant stress response. In this study, based on the unigene GeERF involved in the response to low temperature stress in the transcriptome of G . elegans , a full-length cDNA sequence of the transcription factor GeERF4B-1 was cloned from the leaves of G . elegans by reverse transcription-polymerase chain reaction (RT-PCR). Bioinformatics analysis showed that GeERF4B-1 had an open reading frame of 759 bp, encoding a protein composed of 252 amino acid residues and with a relative molecular weight of 27 kDa. The deduced protein was predicted to be an unstable, alkaline, and hydrophilic protein. The phylogenetic tree showed that GeERF4B-1 was in the same clade as the B-4 subfamily of the ERF family. The results of the subcellular localization experiment revealed that GeERF4B-1 was located in the nucleus. Real time quantitative PCR (RT-qPCR) analysis indicated that GeERF4B-1 was expressed in the root, stem, and leaf of G . elegans , with the highest expression level in the root. Compared with the control, the treatments with a low temperature (4 ℃), methyl jasmonate (MeJA), and abscisic acid (ABA) up-regulated the expression level of GeERF4B-1 , which reached the peak at 24-48 h. This result revealed that GeERF4B-1 actively responded to low temperature, MeJA, and ABA stresses. However, both sodium chloride (NaCl) and drought treatments down-regulated the expression of GeERF4B-1 . In addition, a prokaryotic expression vector of GeERF4B-1 was constructed, and a fusion protein of approximately 52 kDa was yielded after induced expression. The results of the plate stress assay showed that compared with the control, the prokaryotic strain expressing GeERF4B-1 demonstrated enhanced tolerance to low temperatures and sensitivity to salt and mannitol stresses. This study provides theoretical references and potential genetic resources for breeding G . elegans varieties with stress resistance. more...

Associative nitrogen fixation contributes large portion of N input to agro-ecosystems through monocot-diazotrophic associations. However, the contribution of associative nitrogen fixation is usually neglected in modern agriculture, and the underlying mechanisms of association between monocot and diazotrophs remain elusive. Here, we demonstrated that monocot crops employ mucilage and associated benzoic acid to specially enrich diazotrophic partners in response to nitrogen deficiency, which could be used for enhancing associative nitrogen fixation in monocot crops. To be specific, mucilage and benzoic acid induced in sugarcane roots by nitrogen deficiency mediated enrichment of nitrogen-fixing Paraburkholderia through specific recruitment whereas other bacteria were simultaneously repelled. Further studies suggest maize employs a similar strategy in promoting associations with diazotrophs. In addition, our results also suggest that benzoic acid application significantly increases copy numbers of the nifH gene in soils and enhances associative nitrogen fixation in maize using 15N enrichment assay. Taken together, these results reveal a mechanism regulating the association between monocot crops and nitrogen-fixing bacteria, and, thereby point towards ways to harness these beneficial microbes in efforts to increase nitrogen efficiency in monocot crops through pathways regulated by a specific signaling molecule., (© The Author(s) 2024. Published by Oxford University Press on behalf of the International Society for Microbial Ecology.) more...

Objective: To establish an efficient and high resolution 2-DE (two-dimensional electrophoresis) protocol for root tuber proteome analysis of Rehmannia glutinosa., Method: Proteins from root tuber of R. glutinosa were extracted by using five different methods and their productivity and profiles were assessed by means of SDS-PAGE and two-dimensional electrophoresis., Result: The trichloroacetic acid (TCA)-phenol extraction method was found most effective for the extraction with the highest protein yield, the most spots in protein patterns, and the highest resolution of proteins, and the clearest background could be achieved simultaneously. A 1:5 solution of ampholine pH 3-10 and pH 5-8 for a nonlinear gel and the 170 microg of protein loading dosage obtained maps with more protein spots and higher resolution of separation patterns., Conclusion: This study based on the optimized root tuber proteome preparation and the 2-DE protocol gets a high resolution and reproducibility 2-DE image, which will be expected to have excellent applications in proteomics studies of R. glutinosa tuber root. more...