The use of neurotrophic factors to treat Alzheimer’s disease (AD) is hindered by their blood–brain barrier impermeability, short half-life, and severe side effects. Peptide 021 (P021) is a neurotrophic/neurogenic tetra-peptide that was derived from the most active region of the ciliary neurotrophic factor (CNTF) by epitope mapping. Admantylated glycine was added to its C-terminal to increase its blood–brain barrier permeability and decrease its degradation by exopeptidases to make it druggable. Here, we report on the preventive effect of P021 in 3 × Tg-AD, a transgenic mouse model of AD. P021 was administered in the diet at 3 months, i.e., 6–9 months before any overt amyloid beta (Aβ) or tau pathology, and during the period of synaptic compensation, and was continued until 21 months in 3 × Tg-AD mice. The 3 × Tg-AD mice and wild-type (WT) mice were treated identically but with a vehicle-only diet serving as controls. The effects of P021 on neurogenesis, dendritic and synaptic markers, and cognitive performance were investigated. We found that P021 treatment was able to rescue dendritic and synaptic deficits, boost neurogenesis, and reverse cognitive impairment in 3 × Tg-AD mice. Availability of appropriate neurotrophic support during the period of synaptic compensation can prevent synaptic deficit and cognitive impairment, and P021 is a promising neurotrophic compound for this purpose.

Unlike orthodox species, seed recalcitrance is poorly understood, especially at the molecular level. In this regard, seed maturation and germination were studied in the non-orthodox Quercus ilex by using a proteomics strategy based on two-dimensional gel electrophoresis coupled to matrix-assisted laser desorption ionization/time of flight (2-DE-MALDI-TOF).Cotyledons and embryo/radicle were sampled at different developmental stages, including early (M1–M3), middle (M4–M7), and late (M8–M9) seed maturation, and early (G1–G3) and late (G4–G5) germination. Samples corresponding to non-germinating, inviable, seeds were also included. Protein extracts were subjected to 2-dimensional gel electrophoresis (2-DE) and changes in the protein profiles were analyzed. Identified variable proteins were grouped according to their function, being the energy, carbohydrate, lipid, and amino acid metabolisms, together with protein fate, redox homeostasis, and response to stress are the most represented groups. Beyond the visual aspect, morphometry, weight, and water content, each stage had a specific protein signature. Clear tendencies for the different protein groups throughout the maturation and germination stages were observed for, respectively, cotyledon and the embryo axis. Proteins related to metabolism, translation, legumins, proteases, proteasome, and those stress related were less abundant in non-germinating seeds, it related to the loss of viability. Cotyledons were enriched with reserve proteins and protein-degrading enzymes, while the embryo axis was enriched with proteins of cell defense and rescue, including heat-shock proteins (HSPs) and antioxidants. The peaks of enzyme proteins occurred at the middle stages (M6–M7) in cotyledons and at late ones (M8–M9) in the embryo axis. Unlike orthodox seeds, proteins associated with glycolysis, tricarboxylic acid cycle, carbohydrate, amino acid and lipid metabolism are present at high levels in the mature seed and were maintained throughout the germination stages. The lack of desiccation tolerance in Q. ilex seeds may be associated with the repression of some genes, late embryogenesis abundant proteins being one of the candidates.

Rapid global modernization, urbanization, and industrialization have accelerated the release of heavy metals, causing soil pollution. These highly noxious environmental pollutants induce oxidative stress in plants via stimulation of the production of reactive oxygen species (ROS). Thioredoxin (Trxs) is a highly conserved disulfide reductase that plays a crucial role in intracellular redox homeostasis in both eukaryotes and prokaryotes. Herein, the presence of heavy metals highly upregulated LmTrxh2 transcription in Lobularia maritima seedlings and its overexpression-conferred tolerance to Cd, Cu, Mn, and Zn in Saccharomyces cerevisiae. In addition, LmTrxh2-overexpressing tobacco plants had higher seedling survival rates than non-transgenic plants (NT), with enhanced root length and biomass production and reduced ROS accumulation, following Cd and Cu stress. These plants also accumulated more Cd, Cu, and Mn than the NT plants. Moreover, LmTrxh2 overexpression stimulated the transcription of genes encoding metallothioneins (Met-1, Met-2, Met-3, and Met-4), a copper transport protein, a Snakin/GASA protein (Snakin-2), and ROS-scavenging enzymes (SOD, APX1, and CAT), which might contribute to heavy metal tolerance in tobacco plants. These results suggest that LmTrxh2 overexpression helps to improve heavy metal tolerance by stimulating antioxidant capacities and the expression of several stress-responsive genes in plants.

Cold stress is a key environmental factor affecting plant growth and development, crop productivity, and geographic distribution. Thioredoxins (Trxs) are small proteins that are ubiquitously expressed in all organisms and implicated in several cellular processes, including redox reactions. However, their role in the regulation of cold stress in the halophyte plant Lobularia maritima remains unknown. We recently showed that overexpression of LmTrxh2, which is the gene that encodes the h-type Trx protein previously isolated from L. maritima, led to an enhanced tolerance to salt and osmotic stress in transgenic tobacco. This study functionally characterized the LmTrxh2 gene via its overexpression in tobacco and explored its cold tolerance mechanisms. Results of the RT-qPCR and western blot analyses indicated differential temporal and spatial regulation of LmTrxh2 in L. maritima under cold stress at 4 °C. LmTrxh2 overexpression enhanced the cold tolerance of transgenic tobacco, as evidenced by increased germination rate, fresh weight and catalase (CAT), superoxide dismutase (SOD) and peroxidase (POD) activities; reduced malondialdehyde levels, membrane leakage, superoxide anion (O₂⁻), and hydrogen peroxide (H₂O₂) levels; and higher retention of chlorophyll than in non-transgenic plants (NT). Furthermore, the transcript levels of reactive oxygen species (ROS)-related genes (NtSOD and NtCAT1), stress-responsive late embryogenis abundant protein 5 (NtLEA5), early response to dehydration 10C (NtERD10C), DRE-binding proteins 1A (NtDREB1A), and cold-responsive (COR) genes (NtCOR15A, NtCOR47, and NtKIN1) were upregulated in transgenic lines compared with those in NT plants under cold stress, indicating that LmTrxh2 conferred cold stress tolerance by enhancing the ROS scavenging ability of plants, thus enabling them to maintain membrane integrity. These results suggest that LmTrxh2 promotes cold tolerance in tobacco and provide new insight into the improvement of cold-stress resistance to cold stress in non-halophyte plants and crops.

A sufficient and mature vegetative growth is an essential condition for production in the following season and consequently affects the alternate bearing (AB) behavior. However, little is known about its interaction with the crop load and water supply. Herein, we studied the effect of different water regimes and bearing status on the vegetative intensity and flush and its consequence on the flowering parameters of the following season. Rainfed (RF) and fully irrigated (FI) treatments were applied for bearing (ON) and non-bearing (OFF) trees of the ‘Zalmati’ olive orchard in south Tunisia during 2018. The water deficit condition (RF) and the high crop load (ON) have caused a similar decrease in the total node number and shoots length by about 65%. Furthermore, the flowering parameters in 2019, especially the percentage of floral buds (i.e., floral induction intensity), were differentially affected by water supply according to the bearing status of the previous season. FI reduced the percentage of floral buds in 2019 by about 37% for OFF trees, while it increased it by more than four times for the ON trees. Concerning the growth flush, the second (i.e., autumnal) flush seems to respond better to water supply than the first (i.e., spring) one, for both vegetative and flowering parameters. The second flush of growth provided 28% of the total vegetative growth but contributed about 35% to the total number of floral buds for RF OFF trees. Besides, FI makes the first and the second flushes contribute equally to total vegetative growth and to the flowering parameters of the following season. On the other hand, the bearing status of the trees does not affect the contribution of each flush to the total vegetative growth.