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Plant root border cells (RBCs) prevent the colonization of plant growth‐promoting rhizobacteria (PGPR) at the root tip, rendering the PGPR unable to effectively control pathogens infecting the root tip. In this study, we engineered four strains of Pseudomonas sp. UW4, a typical PGPR strain, each carrying an enhanced green fluorescent protein (EGFP)‐expressing plasmid. The UW4E strain harboured only the plasmid, whereas the UW4E‐flg22 strain expressed a secreted EGFP‐Flg22 fusion protein, the UW4E‐Flg(flg22) strain expressed a non‐secreted Flg22, and the UW4E‐flg22‐D strain expressed a secreted Flg22‐DNase fusion protein. UW4E‐flg22 and UW4E‐flg22‐D, which secreted Flg22, induced an immune response in wheat RBCs and colonized wheat root tips, whereas the other strains, which did not secrete Flg22, failed to elicit this response and did not colonize wheat root tips. The immune response revealed that wheat RBCs synthesized mucilage, extracellular DNA, and reactive oxygen species. Furthermore, the Flg22‐secreting strains showed a 33.8%–93.8% higher colonization of wheat root tips and reduced the root rot incidence caused by Rhizoctonia solani and Fusarium pseudograminearum by 24.6%–35.7% compared to the non‐Flg22‐secreting strains in pot trials. There was a negative correlation between the incidence of wheat root rot and colonization of wheat root tips by these strains. In contrast, wheat root length and dry weight were positively correlated with the colonization of wheat root tips by these strains. These results demonstrate that engineered secretion of Flg22 by PGPR is an effective strategy for controlling root rot and improving plant growth. [ABSTRACT FROM AUTHOR]

The 1-aminocyclopropane-1-carboxylic acid (ACC) pathway that synthesizes ethylene is shared in seed plants, fungi and probably other organisms. However, the evolutionary relationship of the key enzyme ACC oxidase (ACO) in the pathway among organisms remains unknown. Herein, we cloned, expressed and characterized five ACOs from the straw mushroom (Volvariella volvacea) and the oyster mushroom (Pleurotus ostreatus): VvACO1-4 and PoACO. The five mushroom ACOs and the previously identified AbACO of the button mushroom contained all three conserved residues that bound to Fe(II) in plant ACOs. They also had variable residues that were conserved and bound to ascorbate and bicarbonate in plant ACOs and harbored only 1–2 of the five conserved ACO motifs in plant ACOs. Particularly, VvACO2 and AbACO had only one ACO motif 2. Additionally, VvACO4 shared 44.23% sequence identity with the cyanobacterium Hapalosiphon putative functional ACO. Phylogenetic analysis showed that the functional ACOs of monocotyledonous and dicotyledonous plants co-occurred in Type I, Type II and Type III, while putative functional gymnosperm ACOs also appeared in Type III. The putative functional bacterial ACO, functional fungi and slime mold ACOs were clustered in ancestral Type IV. These results indicate that ACO motif 2, ACC and Fe(II) are essential for ACO activity. The ACOs of the other organisms may come from the horizontal transfer of fungal ACOs, which were found ordinarily in basidiomycetes. It is mostly the first case for the horizontal gene transfers from fungi to seed plants. The horizontal transfer of ACOs from fungi to plants probably facilitates the fungal-plant symbioses, plant–land colonization and further evolution to form seeds. [ABSTRACT FROM AUTHOR]

To examine the role of T cell receptor (TCR) in γδ T cells in adaptive immunity, a macaque model was used to follow Vγ2Vδ[2.sup.+] T cells responses to mycobacterial infections. These phosphoantigen-specific γδ T cells displayed major expansion during Mycobacterium bovis Bacille Calmette-Guerin (BCG) infection and a clear memory-type response after BCG reinfection. Primary and recall expansions of Vγ2Vδ[2.sup.+] T cells were also seen during Mycobacterium tuberculosis infection of naive and BCG-vaccinated macaques, respectively. This capacity to rapidly expand coincided with a clearance of BCG bacteremia and immunity to fatal tuberculosis in BCG-vaccinated macaques. Thus, Vγ2Vδ[2.sup.+] T cells may contribute to adaptive immunity to mycobacterial infections., The majority of circulating γδ T cells in humans express a TCR heterodimer comprised of Vγ2 and Vδ2 segments. Recent in vitro studies have demonstrated that human Vγ2Vδ[2.sup.+] T cells [...]

The 11α-hydroxylation of 16α, 17-epoxyprogesterone (EP) catalyzed by Rhizopus nigricans is crucial for the steroid industry. However, lower conversion rate of the biohydroxylation restricts its potential industrial application. The 11α-steroid hydroxylase CYP509C12 from R. oryzae were reported to play a crucial role in the 11α-hydroxylation in recombinant fission yeast. In the present study, the CYP509C12 of R. oryzae (RoCYP) was introduced into R. nigricans using the liposome-mediated mycelial transformation. Heterologous expression of RoCYP resulted in increased fungal growth and improved intracellular reactive oxygen species content in R. nigricans. The H2O2 levels in RoCYP transformants were approximately 2-folder that of the R. nigricans wild type (RnWT) strain, with the superoxide dismutase activities increased approximately 45% and catalase activities decreased approximately 68%. Furthermore, the 11α-hydroxylation rates of EP in RoCYP transformants (C4, C6 and C9) were 39.7%, 38.3% and 38.7%, which were 12.1%, 8.2% and 9.4% higher than the rate of the RnWT strain, respectively. This paper investigated the effect of heterologous expression of RoCYP in R. nigricans, providing an effective genetic method to construct the engineered strains for steroid industry. [ABSTRACT FROM AUTHOR]