Plants

The thioredoxin h-type (Trxh) proteins play a crucial role as convergence points within plants’ responses to abiotic and biotic stresses. Previously, we demonstrated that the protein TdTrxh2 of durum wheat (Triticum durum Desf.) has a chaperone function and it promotes tolerance to abiotic stress. The aim of this study was to evaluate the antimicrobial effect of TdTrxh2 and its role in the response of durum wheat to Fusarium graminearum attack. First, we demonstrated the involvement of TdTrxh2 in the response of durum wheat to this fungus via the analysis of its expression profile under this fungus attack. In fact, the outcomes showed that the induction of TdTrxh2 expression is spatiotemporal in leaves and roots of durum wheat under F. graminearum infection. Interestingly, this induction was accompanied by H₂O₂ accumulation under short- and long-term stress in roots and leaves, respectively. Besides, the cis elements related to the two phytohormones ET and MeJA, and those implicated in defense and wound stress, were identified in the TdTrxh2 promoter’s sequence. Second, the purified TdTrxh2 protein possessed antimicrobial effects against a diverse range of bacteria and fungi in vitro. Finally, the expression of TdTrxh2 in transgenic Arabidopsis plants enhanced their tolerance to F. graminearum attack through the activation of the two H₂O₂-scavenging enzymes, CAT and POD, and via the induction of a subset of SA- and ABA-related genes. Moreover, the exogenous SA and ABA applications improved the growth of the transgenic lines compared to the non-transformed plants. Taken together, the results highlighted that TdTrxh2 generates tolerance of durum wheat’s response to F. graminearum attack, via the regulation of H₂O₂ homeostasis and the induction of hormone-associated genes. Thus, the TdTrxh2 gene could be considered as an interesting candidate gene to improve wheat tolerance to F. graminearum attack.

Ammonium transporters (AMTs) are a class of membrane-associated proteins that play crucial roles in the uptake and transport of ammonium (NH₄⁺ or NH₃). In this study, an ammonium transporter-encoding gene VviAMT4;1 was isolated and identified from table grape ‘Yanpu No.2’. Notably, the expression level of VviAMT4;1 varied significantly across different organs or tissues of ‘Yanpu No.2’, and the highest expression level was detected in the roots of both tissue-cultured seedlings and 5-year-old mature trees. Expression of VviAMT4;1 was significantly up-regulated under NH₄⁺ depletion throughout the whole of tissue-cultured seedlings. Yeast mutant functional complementation indicates that the recombinant strain pYES2-VviAMT4;1/31019b restored growth under different pH conditions. ¹⁵N isotope-labeled uptake kinetics analysis demonstrated that VviAMT4;1 is a typical high-affinity ammonium transporter, with a Kₘ value of 49.58 ± 4.66 μmol·L⁻¹ and a Vₘₐₓ value of 3.29 μmoles·min⁻¹·μg⁻¹ cells. Moreover, VviAMT4;1 can mediate the weak uptake and utilization of methyl amine (MeA⁺) in yeast cells. The VviAMT4;1-mediated NH₄⁺ uptake process may suffer from feedback inhibition by endogenous NH₄⁺ enrichment. This study provides insights into understanding the molecular mechanisms of N transport and utilization in fruit trees.

Agricultural productivity currently faces challenges such as soil fertility issues, climatic instability, pests and diseases, and anthropization. This drives a shift towards sustainable agricultural practices, including biopreparations—products derived from living organisms or their metabolites that serve as biofertilizers, biopesticides, biostimulants, or biodegradation agents. Among these, the genus Bacillus is a primary candidate for sustainable agriculture; however, this review primarily covers rhizosphere-isolated organisms referred to as plant growth-promoting rhizobacteria. Bacillus strains possess a suite of direct and indirect mechanisms to promote plant development and biocontrol, as well as to tolerate various abiotic stresses. This review aims to describe all the mechanisms attributed to strains of this genus and their impact on different crops to promote plant growth, hormonal regulation (indole-3-acetic acid (IAA), abscisic acid (ABA), and ethylene), tolerance to abiotic stresses such as drought, heavy metals, salinity and heat stress, as well as resistance to pests and diseases. Furthermore, this work analyzes quantitative data regarding yield improvements and the environmental variables that influence the consistency of Bacillus performance in the field. Finally, to provide a balanced perspective, the review incorporates future directions in research on biosafety and risk assessment frameworks.