Plants apply various molecular, physiological and morphological strategies in response to undesirable environmental conditions. One of the possible responses which may contribute to surviving stressful conditions is the accumulation of ureides. Ureides are recognized as important nitrogen-rich compounds involved in recycling nitrogen in plants to support growth and reproduction. Amongst them, allantoin not only serves as a transportable nitrogen-rich compound, but has also been suggested to protect plants from abiotic stresses via minimizing oxidative damage. This work focuses on the effect of cadmium (Cd) on ureide metabolism in Arabidopsis, in order to clarify the potential role of allantoin in plant tolerance to heavy metals. In response to Cd treatment, allantoin levels increase in Arabidopsis thaliana, ecotype Col-0, due to reduced allantoinase (ALN) gene expression and enzyme activity. This coincides with increases in uricase (UO) transcripts. UO and ALN encode the enzymes for the production and degradation of allantoin, respectively. ALN-negative aln-3 Arabidopsis mutants with elevated allantoin levels demonstrate resistance to soil-applied CdCl, up to 1,500 μM. Although aln-3 mutants take up and store more Cd within their leaf tissue, they contain less damaging superoxide radicals. The protective mechanism of aln-3 mutants appears to involve enhancing the activity of antioxidant enzymes such as superoxide dismutase and ascorbate peroxidase.
We report here the synthesis and biological testing of 3’-phenyl alkynyl abscisic ABA analogs, a new class of potent ABA antagonists. These ABA analogs incorporate a rigid framework of eight...
Nitrous oxide (N2O) is a potent greenhouse gas (GHG). Although it comprises only 0.03% of total GHGs produced, N2O makes a marked contribution to global warming. Much of the N2O in the atmosphere issues from incomplete bacterial denitrification processes acting on high levels of nitrogen (N) in the soil due to fertilizer usage. Using less fertilizer is the obvious solution for denitrification mitigation, but there is a significant drawback (especially where not enough N is available for the crop via N deposition, irrigation water, mineral soil N, or mineralization of organic matter): some crops require high-N fertilizer to produce the yields necessary to help feed the world’s increasing population. Alternatives for denitrification have considerable caveats. The long-standing promise of genetic modification for N fixation may be expanded now to enhance dissimilatory denitrification via genetic engineering. Biotechnology may solve what is thought to be a pivotal environmental challenge of the 21st century, reducing GHGs. Current approaches towards N2O mitigation are examined here, revealing an innovative solution for producing staple crops that can ‘crack’ N2O. The transfer of the bacterial nitrous oxide reductase gene (nosZ) into plants may herald the development of plants that express the nitrous oxide reductase enzyme (N2OR). This tactic would parallel the precedents of using the molecular toolkit innately offered by the soil microflora to reduce the environmental footprint of agriculture.
The COVID-19 pandemic has brought to the forefront an urgent need for the rapid development of highly efficacious vaccines, particularly in light of the ongoing emergence of multiple variants of concern. Plant-based recombinant protein platforms are emerging as cost-effective and highly scalable alternatives to conventional protein production. Viral glycoproteins, however, are historically challenging to produce in plants. Herein, we report the production of plant-expressed wild-type glycosylated SARS-CoV-2 Spike RBD (receptor-binding domain) protein that is recognized by anti-RBD antibodies and exhibits high-affinity binding to the SARS-CoV-2 receptor ACE2 (angiotensin-converting enzyme 2). Moreover, our plant-expressed RBD was readily detected by IgM, IgA, and IgG antibodies from naturally infected convalescent, vaccinated, or convalescent and vaccinated individuals. We further demonstrate that RBD binding to the ACE2 receptor was efficiently neutralized by antibodies from sera of SARS-CoV-2 convalescent and partially and fully vaccinated individuals. Collectively, these findings demonstrate that recombinant RBD produced in planta exhibits suitable biochemical and antigenic features for use in a subunit vaccine platform.
Agroinfiltration is a method used in biopharming to support plant-based biosynthesis of therapeutic proteins such as antibodies and viral antigens involved in vaccines. Major advantages of generating proteins in plants is the low cost, massive scalability and the rapid yield of the technology. Herein, we report the agroinfiltration-based production of glycosylated SARS-CoV-2 Spike receptor-binding domain (RBD) protein. We show that it exhibits high-affinity binding to the SARS-CoV-2 receptor angiotensin-converting enzyme 2 (ACE2) and displays folding similar to antigen produced in mammalian expression systems. Moreover, our plant-expressed RBD was readily detected by IgM, IgA, and IgG antibodies from the serum of SARS-CoV-2 infected and vaccinated individuals. We further demonstrate that binding of plant-expressed RBD to ACE2 is efficiently neutralized by these antibodies. Collectively, these findings demonstrate that recombinant RBD produced via agroinfiltration exhibits suitable biochemical and antigenic features for use in serological and neutralization assays, and in subunit vaccine platforms.
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