The increase in environmental temperature due to global warming is a critical threat to plant growth and productivity. Heat stress can cause impairment in several biochemical and physiological processes. Plants sense and respond to this adverse environmental condition by activating a plethora of defense systems. Among them, the heat stress response (HSR) involves an intricate network of heat shock factors (HSFs) and heat shock proteins (HSPs). However, a growing amount of evidence suggests that reactive oxygen species (ROS), besides potentially being responsible for cellular oxidative damage, can act as signal molecules in HSR, leading to adaptative responses. The role of ROS as toxic or signal molecules depends on the fine balance between their production and scavenging. Enzymatic and non-enzymatic antioxidants represent the first line of defense against oxidative damage and their activity is critical to maintaining an optimal redox environment. However, the HS-dependent ROS burst temporarily oxidizes the cellular environment, triggering redox-dependent signaling cascades. This review provides an overview of the redox-activated mechanisms that participate in the HSR.

Cereals are the most broadly produced crops and represent the primary source of food worldwide. Nitrogen (N) is a critical mineral nutrient for plant growth and high yield, and the quality of cereal crops greatly depends on a suitable N supply. In the last decades, a massive use of N fertilizers has been achieved in the desire to have high yields of cereal crops, leading to damaging effects for the environment, ecosystems, and human health. To ensure agricultural sustainability and the required food source, many attempts have been made towards developing cereal crops with a more effective nitrogen use efficiency (NUE). NUE depends on N uptake, utilization, and lastly, combining the capability to assimilate N into carbon skeletons and remobilize the N assimilated. The glutamine synthetase (GS)/glutamate synthase (GOGAT) cycle represents a crucial metabolic step of N assimilation, regulating crop yield. In this review, the physiological and genetic studies on GS and GOGAT of the main cereal crops will be examined, giving emphasis on their implications in NUE.

Background and aims: The quantification of plant roots from soil represents a pivotal step in many studies in plant ecology and soil science. However, the substantial time investment required for this process often represents a considerable impediment to research progress. The objective of this study is to evaluate and propose a time-saving method to minimize the time required for collecting roots without compromising data integrity compared to traditional approaches. Methods: The proposed Sub-sample Approach (SA) requires collecting fine roots from a sub-sample and subsequently leading calculations to estimate total root traits (mass, length, and length distribution among diameters) within the sampled soil core. A comparative analysis was carried out on root harvesting time between meticulous sample cleaning (Conventional Approach, CA) and SA. Moreover, these methods were assessed across different sites including grassland, oak forest, and olive orchard. Results: The analysis conducted across many sites resulted in high heterogeneity of processing time when employing the CA (ranging from 2.6 to 27.6 h per sample). Conversely, the adoption of SA reduced processing time and resulted in less variation between samples (ranging from 37 to 112 min per sample). Remarkably, root trait data obtained using SA showed similarity to those obtained through the CA. Conclusion: The SA offers a remarkable advantage over the CA by significantly reducing the time needed for root collection from soil core samples. Moreover, SA exhibits lower variability among different collection sites, while maintaining consistency in qualitative and quantitative data compared to the CA.

ATP-binding cassette (ABC) transporters mediate substrate translocation across membranes by using energy from ATP hydrolysis. While ABC peptide exporters have been characterized in the mitochondria of metazoans and yeast, corresponding chloroplast peptide transport systems in plants remain uncharacterized. Using in silico and experimental approaches, we identify three previously uncharacterized Arabidopsis thaliana ABCB half-transporters - TAP1, NAP8, and ATH12 - that localize to the chloroplast inner envelope and form homodimers. These proteins are phylogenetically related to known peptide exporters, and functional complementation in Saccharomyces cerevisiae demonstrates that each plant transporter can rescue the heat sensitivity of a Δmdl1 mutant, indicating conserved peptide export activity. In chloroplast peptide efflux assays, peptide export upon heat stress was strongly reduced only in the tap1 nap8 ath12 triple mutant, but not in single or double mutants, indicating functional redundancy. Furthermore, mass spectrometry of chloroplast supernatants revealed an abundance of thylakoid-derived hydrophilic peptides in the wild type, predicted to have antioxidant activity. Under heat stress, the triple mutant displayed increased sensitivity, characterized by reduced biomass, chlorophyll and carotenoid content, and compromised photosynthetic efficiency. Comprehensive analyses revealed altered redox homeostasis in the triple mutant, including modified antioxidant dynamics, differential antioxidant enzyme activities, and distinct gene expression profiles compared with the wild type. Our findings demonstrate that TAP1, NAP8, and ATH12 constitute a chloroplast peptide export system required for efficient peptide release under heat stress, with a role in Arabidopsis thermotolerance. These results provide new insights into organellar peptide transport and its integration with stress mitigation mechanisms in plants.

Soil degradation can strongly constrain plant establishment and ecosystem restoration, highlighting the need for amendments able to improve both soil functionality and plant–microbiome interactions. This study evaluated whether biochar preconditioned for six months in healthy pine forest soil could enhance the early growth of Pinus halepensis Mill. compared with untreated biochar in degraded agricultural soil. Seedlings were grown for 85 days under controlled conditions in five substrates, including pine forest soil, non-intensively cultivated agricultural soil, degraded agricultural soil, and degraded soil amended with either untreated or bioactivated biochar. Above- and below-ground plant morphological traits, soil chemistry, and rhizosphere microorganism communities were assessed. Untreated biochar markedly promoted root development, increasing absorptive fine-root length, root biomass, and stem diameter compared with degraded soil and forest-conditioned biochar. In contrast, bioactivated biochar resulted in more limited early seedling growth. Microbial community composition varied among treatments, whereas Shannon diversity did not differ significantly. Bacterial communities showed partial overlap among treatments, while fungal communities displayed clearer treatment-associated separation. Overall, forest-soil conditioning did not improve biochar effectiveness during early seedling development. Further drought and field trials are required to determine whether these contrasting growth and rhizosphere responses influence long-term establishment and restoration performance.