Melatonin (N-acetyl-5-methoxytryptamine) plays an important role in plant growth and development, and in the response to various abiotic stresses. However, its role in the responses of barley to low phosphorus (LP) stress remains largely unknown. In the present study, we investigated the root phenotypes and metabolic patterns of LP-tolerant (GN121) and LP-sensitive (GN42) barley genotypes under normal P, LP, and LP with exogenous melatonin (30 μM) conditions. We found that melatonin improved barley tolerance to LP mainly by increasing root length. Untargeted metabolomic analysis showed that metabolites such as carboxylic acids and derivatives, fatty acyls, organooxygen compounds, benzene and substituted derivatives were involved in the LP stress response of barley roots, while melatonin mainly regulated indoles and derivatives, organooxygen compounds, and glycerophospholipids to alleviate LP stress. Interestingly, exogenous melatonin showed different metabolic patterns in different genotypes of barley in response to LP stress. In GN42, exogenous melatonin mainly promotes hormone-mediated root growth and increases antioxidant capacity to cope with LP damage, while in GN121, it mainly promotes the P remobilization to supplement phosphate in roots. Our study revealed the protective mechanisms of exogenous MT in alleviating LP stress of different genotypes of barley, which can be used in the production of phosphorus-deficient crops.

Leaf color mutants are commonly characterized by altered chlorophyll content and aberrant chloroplast development, making them valuable models for investigating photosynthetic mechanisms and chloroplast biogenesis. In this study, an albino mutant was isolated from a population of transgenic maize breeding lines. Genetic analysis indicated that the mutant phenotype is inherited in a Mendelian manner and is controlled by a single nuclear locus. This was supported by a χ² test performed on the T₂ generation, which confirmed a segregation ratio consistent with 3:1 (176:68, χ² = 1.07 < χ²_0.05 = 3.84, p > 0.05). Microscopic examination revealed the absence of normally developed chloroplasts in mutant cells. Further expression analysis of chloroplast genes via Northern blotting and quantitative real-time PCR (qRT-PCR) suggested that the mutation impairs the regulation of plastid-encoded polymerase (PEP)-dependent chloroplast gene expression. Notably, PCR-based co-segregation analysis indicated that the mutant phenotype is associated with the entire inserted vector sequence, rather than a point mutation or a small genomic deletion. In conclusion, this paper reports the isolation and phenotypic characterization of an etiolated mutant from a transgenic maize breeding population, including comparative ultrastructural analysis of chloroplasts, co-segregation validation, and chloroplast gene expression profiling. These results enhance our understanding of the physiological and molecular mechanisms underlying chlorophyll-deficient mutations in plants.

Malic enzyme (ME), a key enzyme involved in various metabolic pathways, catalyzes the oxidative decarboxylation of malate to generate pyruvate, CO₂, and NADPH. This enzyme plays essential roles in plant growth, development, and stress responses. In this study, 13 maize ME genes were identified by performing homologous sequence alignment using the sequences of the Arabidopsis ME gene family as references. Chromosomal localization analysis demonstrated that ME genes were not detected on chromosomes 9 and 10, whereas the remaining eight chromosomes exhibited an uneven distribution of these genes. Phylogenetic analysis indicated a high degree of conservation between maize ME genes and their orthologs in teosinte (Zea luxurians L.) throughout the evolutionary history of Poaceae crops. Furthermore, cis-acting element analysis of promoters demonstrated that members of the maize ME gene family harbor regulatory elements associated with stress responses, phytohormones signaling, and light responsiveness, which suggests their potential role in abiotic stress adaptation. Expression profiling under stress conditions revealed differential expression levels of maize ME genes, with ZmME13 emerging as a promising candidate gene for enhancing stress resistance. These results lay a solid foundation for further investigation into the biological functions of the maize ME gene family.

Understanding the recovery of soil fauna communities in reclaimed mining areas is essential for evaluating the ecological effectiveness of restoration practices in alpine ecosystems. However, the combined effects of altitudinal gradients and soil physicochemical filters on soil fauna assembly during the early stages of coal mine reclamation remain poorly understood. Here, we investigated soil fauna communities across altitudinal gradients (2260–3070 m) in the Gansu Qilian Mountain Nature Reserve, integrating linear mixed-effects models (LMM), non-metric multidimensional scaling (NMDS), permutational multivariate analysis of variance (PERMANOVA), similarity percentage (SIMPER) analysis, hierarchical partitioning (HP), and Bayesian structural equation modeling (BSEM) to disentangle the direct and indirect drivers of community composition and diversity. Our results revealed that A total of 41 families from 15 orders were identified, with Hymenoptera and Coleoptera dominant. LMM revealed a significant altitude × reclamation interaction on activity density and taxonomic richness. PERMANOVA showed altitude as the primary community driver. Diversity indices showed no significant differences between reclaimed and natural sites at equivalent elevations. Hierarchical partitioning identified total phosphorus (24.85%), sand (13.00%), and pH (12.15%) as the top environmental predictors, while BSEM indicated that altitude influenced fauna indirectly through soil properties, with electrical conductivity exerting a direct positive effect (β = 0.62). Our findings demonstrate that reclamation promotes partial recovery of soil fauna, with several community-level metrics converging toward natural reference levels, although full restoration has not been achieved. Recovery outcomes are strongly elevation-dependent, emphasizing the need for altitude-specific management strategies in alpine mining regions.