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Mycobacterium avium subsp. paratuberculosis (MAP) is the etiological agent of Paratuberculosis, a contagious, untreatable, and chronic granulomatous enteritis that results in diarrhea, emaciation, and death in farmed ruminants (i.e., cattle, sheep, and goats). In this study, the Ag85B antigen from MAP was expressed in transgenic alfalfa as an attractive vaccine candidate. Agrobacterium-mediated transformation allowed the rescue of 56 putative transformed plants and transgenesis was confirmed in 19 lines by detection of the Ag85B gene (MAP1609c) by PCR. Line number 20 showed the highest Ag85B expression [840 ng Ag85B per gram of dry weight leaf tissue, 0.062% Total Soluble Protein (TSP)]. Antigenicity of the plant-made Ag85B was evidenced by its reactivity with a panel of sera from naturally MAP-infected animals, whereas immunogenicity was assessed in mice immunized by either oral or subcutaneous routes. The plant-made Ag85B antigen elicited humoral responses by the oral route when co-administered with cholera toxin as adjuvant; significant levels of anti-85B antibodies were induced in serum (IgG) and feces (IgA). Long-lasting immunity was evidenced at day 180 days post-first oral immunization. The obtained alfalfa lines expressing Ag85B constitute the first model of a plant-based vaccine targeting MAP. The initial immunogenicity assessment conducted in this study opens the path for a detailed characterization of the properties of this vaccine candidate. Supplementary Information The online version contains supplementary material available at 10.1007/s12033-021-00307-w.

β-glucosidases participate (EC 3.2.1.21) in the activation of glycosylated and inactive forms of various compounds during plant response to the environmental conditions. The understanding of regulatory mechanisms for β-glucosidases in each plant species and their functionality is the purpose of various investigations. Our study reports the expression analysis of 10 β-glucosidase genes in corn seedlings after a challenge infection ith Fusarium proliferatum and Ustilago maydis compared with the gene expression analysis after mechanical damage and without damage to the seedlings under in vitro culture conditions. Likewise, the heterologous sequence comparison of the β-glucosidases from Zea mays and the characterized β-glucosidases of Oryza sativa and Arabidopsis thaliana were reported. Our results suggest a potential similitude in the functionality of this group of β-glucosidase genes in maize during the response to biotic stress and the mechanical damage that also showed possible tissue-specific regulation. Our results suggest the transcription regulation of these β-glucosidases and their possible influence in the defence mechanism against fungal infections in maize.

Plants exhibit several mechanisms to survive under high salinity conditions. The uptake and compartmentalization of Na+ ion by the NHX antiporter is a crucial mechanism in homeostasis maintenance. Therefore, we evaluated McNHX2 gene expression and several physiological responses induced in three natural genetic variants of ice plants under salt stress. Based on morphology and growth behavior of wild type populations from an arid region of northwestern Mexico, we identified three ice plant natural genetic variants and called P0, P9, and P11. Several physiological parameters, such as water potential, relative water content, chlorophyll, and Na+ and K+ ion contents from all natural genetic variants exhibited a differential response under high salinity conditions. Specifically, the P0 variant showed lower water potential changes and least perturbation of Na+/K+ ratio than those of the P9 and P11 variants under saline conditions, suggesting that the P0 variant is the most salt tolerant. Unexpectedly, McNHX2 expression was repressed in the P11 variant while it was upregulated in the P0 and P9 variants under saline treatments. The McNHX2 gene was sequenced showing 15 introns and 16 exons; polymorphisms were found among the cDNAs sequences from the three natural genetic variants. All these data suggest that differential responses to high salinity involve different mechanisms operating in each variant for counteracting saline stress effects.