The NPR1 (nonexpressor of pathogenesis-related genes 1) gene is an activator of the systemic acquisition of resistance (SAR) in plants and is one of the central factors in their response to pathogenic bacterial infestation, playing an important role in plant disease resistance. Potato (Solanum tuberosum) is a crucial non-grain crop that has been extensively studied. However, the identification and analysis of the NPR1-like gene within potato have not been understood well. In this study, a total of six NPR1-like proteins were identified in potato, and phylogenetic analysis showed that the six NPR1-like proteins in Solanum tuberosum could be divided into three major groups with NPR1-related proteins from Arabidopsis thaliana and other plants. Analysis of the exon–intron patterns and protein domains of the six NPR1-like genes from potato showed that the exon–intron patterns and protein domains of the NPR1-like genes belonging to the same Arabidopsis thaliana subfamily were similar. By performing quantitative real-time PCR (qRT-PCR) analysis, we found that six NPR1-like proteins have different expression patterns in different potato tissues. In addition, the expression of three StNPR1 genes was significantly downregulated after being infected by Ralstonia solanacearum (RS), while the difference in the expression of StNPR2/3 was insignificant. We also established potato StNPR1 overexpression lines that showed a significantly increased resistance to R. solanacearum and elevated activities of chitinase, β-1,3-glucanase, and phenylalanine deaminase. Increased peroxidase (POD), superoxide dismutase (SOD), and catalase (CAT) activities, as well as decreased hydrogen peroxide, regulated the dynamic balance of reactive oxygen species (ROS) in the StNPR1 overexpression lines. The transgenic plants activated the expression of the genes associated with the Salicylic acid (SA) defense response but suppressed the expression of the genes associated with Jasmonic acid (JA) signaling. This resulted in resistance to Ralstonia solanacearum.

Expansin is a cell wall relaxant protein that is common in plants and directly or indirectly participates in the whole process of plant root growth, development and morphogenesis. A well-developed root system helps plants to better absorb water and nutrients from the soil while effectively assisting them in resisting osmotic stress, such as salt stress. In this study, we observed and quantified the morphology of the roots of Arabidopsis overexpressing the TaEXPAs gene obtained by the research group in the early stage of development. We combined the bioinformatics analysis results relating to EXPA genes in five plants and identified TaEXPA7-B, a member of the EXPA family closely related to root development in winter wheat. Subcellular localization analysis of the TaEXPA7-B protein showed that it is located in the plant cell wall. In this study, the TaEXPA7-B gene was overexpressed in rice. The results showed that plant height, root length and the number of lateral roots of rice overexpressing the TaEXPA7-B gene were significantly higher than those of the wild type, and the expression of the TaEXPA7-B gene significantly promoted the growth of lateral root primordium and cortical cells. The plants were treated with 250 mM NaCl solution to simulate salt stress. The results showed that the accumulation of osmotic regulators, cell wall-related substances and the antioxidant enzyme activities of the overexpressed plants were higher than those of the wild type, and they had better salt tolerance. This paper discusses the effects of winter wheat expansins in plant root development and salt stress tolerance and provides a theoretical basis and relevant reference for screening high-quality expansin regulating root development and salt stress resistance in winter wheat and its application in crop molecular breeding.

Background: Iva xanthiifolia, native to North America, is now widely distributed in northeastern China and has become a vicious invasive plant. This article aims to probe the role of leaf extract in the invasion of I. xanthiifolia. Methods: We collected the rhizosphere soil of Amaranthus tricolor and Setaria viridis in the invasive zone, the noninvasive zone and the noninvasive zone treated with extract from I. xanthiifolia leaf, and obtained I. xanthiifolia rhizosphere soil in the invasive zone. All wild plants were identified by Xu Yongqing. I. xanthiifolia (collection number: RQSB04100), A. tricolor (collection number: 831,030) and S. viridis (collection number: CF-0002-034) are all included in Chinese Virtual Herbarium (https://www.cvh.ac.cn/index.php). The soil bacterial diversity was analyzed based on the Illumina HiSeq sequencing platform. Subsequently, taxonomic analysis and Faprotax functional prediction were performed. Results: The results showed that the leaf extract significantly reduced the diversity of indigenous plant rhizosphere bacteria. A. tricolor and S. viridis rhizobacterial phylum and genus abundances were significantly reduced under the influence of I. xanthiifolia or its leaf extract. The results of functional prediction showed that bacterial abundance changes induced by leaf extracts could potentially hinder nutrient cycling in native plants and increased bacterial abundance in the A. tricolor rhizosphere related to aromatic compound degradation. In addition, the greatest number of sensitive Operational Taxonomic Units (OTUs) appeared in the rhizosphere when S. viridis was in response to the invasion of I. xanthiifolia. It can be seen that A. tricolor and S. viridis have different mechanisms in response to the invasion of I. xanthiifolia. Conclusion: I. xanthiifolia leaves material has potential role in invasion by altering indigenous plant rhizosphere bacteria.

BackgroundLow temperature is an important factor that influences the ability of winter wheat to safely overwinter. Excessive low temperatures restrict the regrowth of winter wheat, thus decreasing agricultural output. Non-enzymatic expansins, which are related to plant growth, have been reported to respond to drought, salinity, and low temperature stress. We obtained an expansin gene, TaEXPA9, that is induced by low temperature from a transcriptome analysis of ‘Dongnong winter wheat no. 2’—a winter wheat with high cold hardiness—but the expression pattern and function of this gene were unknown. We therefore analyzed the expression patterns of TaEXPA9-A/B/D in D2 in response to different abiotic stresses and exogenous phytohormone treatments in different organs. The entire length of TaEXPA9-A/B/D was obtained, and green fluorescent labeling was used for subcellular localization analysis of TaEXPA9-A/B/D on onion epidermis. The 35S::TaEXPA9-A/B/D expression vector was constructed, and an overexpression transgenic Arabidopsis thaliana line was obtained to examine the effects of the homologs of this expansin on plant growth and low temperature stress resistance. ResultsThe results showed that TaEXPA9-A/B/D transcription significantly increased at 4°C low temperature stress, its expression level was higher in the roots, and TaEXPA9-A/B/D was localized to the cell wall. The roots were well-developed in the overexpression A. thaliana, and the growth-related markers and setting rate were better than in the wild-type. Recovery was stronger in the overexpression plants after frost stress. At 4°C low temperature stress, the antioxidant enzyme activity and osmoregulatory substance content in the TaEXPA9-A/B/D-overexpressing A. thaliana plants were significantly higher than in the wild-type plants, and the degree of membrane lipid peroxidation was lower. ConclusionsIn summary, TaEXPA9-A/B/D participates in the low-temperature stress response and may increase the scavenging of reactive oxygen species caused by low temperature stress through the protective enzyme system. Additionally, TaEXPA9-A/B/D can increase the levels of small molecular organic substances to resist osmotic stress caused by low temperature.