Abscisic acid (ABA) mediated stomatal closure is a highly effective mode of active stomatal regulation under drought stress. Previous studies on stomatal regulation have primarily focused on the leaves of vascular plants, while research on the stomatal behavior of bulbous plants remains unknown. In addition, ABA-induced stomatal regulation in bulbs has yet to be explored. Therefore, we aim to investigate the ABA-induced active regulation in the bulb of the Lanzhou lily (Lilium davidii var. unicolor). The morphological characteristics of epidermal strips were analyzed along with a stomatal aperture assay to investigate the bulb's stomatal response to ABA. Moreover, the mechanism of ABA signaling was explored using treatments with ABA signaling chemicals and corresponding scavengers. This study revealed that stomata are mainly distributed on the upper part and outer surface of the bulb. The guard cells of the lily bulb are inflated, and the stomata have a nearly circular shape with relatively low stomatal density. Exogenous ABA was found to induce varying degrees of stomatal closure in a dose-dependent manner, with significant stomatal aperture reduction observed after treatment with 10 µM ABA. Overall, the study indicated that both hydrogen peroxide (H₂O₂) and nitric oxide (NO) are involved in the ABA-induced stomatal closure process, with H₂O₂ functioning as an upstream component of NO.

Stomatal pores, controlled by surrounding guard cells, play a crucial role in balancing carbon dioxide (CO₂) uptake and water loss in plants. Recent studies in Arabidopsis thaliana have identified the TARGET OF TEMPERATURE 3 (TOT3)–plasma membrane (PM) H⁺-ATPase (AHA1) module as a key player in stomatal movement, though its exact role in vascular plants is not yet fully understood. TOT3, a transcriptional regulator, influences the activity of AHA1, which regulates ion fluxes essential for stomatal opening. Under high-temperature conditions, TOT3 promotes stomatal opening, while OST1, a key regulator of drought-induced stomatal closure, inactivates TOT3 through phosphorylation. This phosphorylation serves as a molecular switch, adjusting stomatal aperture in response to heat and drought stress. Moreover, light may also impact stomatal movement via the TOT3–AHA1 interaction. This review explores the molecular mechanisms underlying the TOT3–AHA1 module, its integration with abscisic acid (ABA) signaling, and its role in plant adaptation to environmental stresses. Understanding this pathway could contribute to developing crops with enhanced water-use efficiency and resilience to abiotic stress.

Background: Plastid RNA editing is widespread in angiosperms yet remains underexplored in the medicinal non-model species Glycyrrhiza uralensis. This study aimed to (i) comprehensively identify plastid RNA editing sites in G. uralensis, and (ii) compare the detection performance of three library construction strategies: total RNA-seq, rRNA-depleted RNA-seq, and mRNA-seq. Methods: Leaf tissue was used from three wild-sampled individual plants. Plastomes were assembled with GetOrganelle v1.7.0 and annotated using PGA. Strand-specific RNA-seq libraries were mapped to sample-matched plastomes using HISAT2 v2.2.1. Variants were identified using REDItools v2.0 under uniform thresholds. Candidate sites were visually verified in IGV v2.12.3, and read origins were confirmed by BLAST v2.13.0+; artifacts were removed via strand-specific filtering. Results: After stringent filtering, 38 high-confidence RNA editing sites were identified across 19 genes. Total RNA seq performed the best, detecting 37/38 sites consistently, whereas rRNA-depleted libraries detected fewer genuine sites and produced numerous rRNA-linked, noncanonical, noncoding-strand-dominant artifacts. Despite very low rates of plastid mapping, mRNA seq recovered a large fraction of bona fide sites under stringent, strand-aware filtering. Conclusions: We establish a set of 38 high-confidence plastid RNA editing sites in G. uralensis and suggest potential adaptive implications of editing in ndh-related genes. Methodologically, total RNA-seq is recommended for identification using de novo RNA editing due to its high sensitivity and low false-positive rate; publicly available poly(A)-selected mRNA-seq datasets can be repurposed to reliably retrieve plastid RNA editing sites when stringent strand-specific filtering is applied.

In response to drought stress, abscisic acid (ABA) plays a crucial role in regulating stomatal closure in both leaf and floral tissues. Studies on stomatal regulation have primarily focused on the leaves of vascular plants, but stomatal regulation of flowers remains underexplored. The current study was conducted on the petals of ‘Ma Lin’ daylily (Hemerocallis citrina Baroni) to assess the morphological characteristics of petal stomata, stomatal aperture, gas exchange, and the mechanisms of ABA signaling in response to treatments with ABA-related chemicals and their corresponding scavengers. The study showed that stomata are primarily located in the lower epidermis of the petals, arranged in a strip near the central vein, and exhibit relatively low density; the guard cells contain a large number of chloroplasts. Exogenous ABA induced stomatal closure in the petal stomata, and the gas exchange assay indicated that stomatal conductance decreased when exogenous ABA was introduced into the transpiration stream. The stomatal aperture assay revealed a 32.78% decrease following a 10 µM ABA treatment. Furthermore, both hydrogen peroxide (H₂O₂) and nitric oxide (NO) were involved in the ABA-induced stomatal closure process, with H₂O₂ acting as an upstream component of NO. Overall, these results suggest that physiologically active stomatal control is present in the flower of ‘Ma Lin’ daylily under drought stress, consistent with the regulation observed in leaf stomata.

Flowering time is an important trait affecting regional adaptation and yield stability in rapeseed (Brassica napus). To dissect the genetic basis of flowering time and vernalization-type differentiation in B. napus, this study integrated genome-wide SNPs, flowering-time phenotypes, vernalization types, and geographic origin information to establish a candidate QTL discovery framework combining genome-wide association study (GWAS) and machine learning. Based on 8,387,529 high-quality SNPs, GWAS was performed using the FarmCPU model under two covariate settings: a PC-corrected model and a PC + vernalization type-corrected model. These two models identified 32 and 27 suggestive SNPs, respectively. In parallel, ExtraTreesRegressor was used to estimate the feature contribution of SNPs to flowering-time prediction, leading to the identification of 18,854 ML_delta10SD high-contribution SNPs, which were further merged into 997 ML-derived candidate QTL intervals, hereafter referred to as ML-QTLs. By integrating GWAS-derived QTLs and ML-QTLs at the interval level, 34 GWAS- and ML-supported candidate regions were prioritized. Candidate gene annotation revealed that these regions contained genes related to flowering regulation, including FLC, FRIGIDA-like, VIN3-like, SOC1, ELF3, CONSTANS-like, APETALA1-like, and genes involved in the gibberellin pathway. Top-SNP genotypic effect analysis and multi-SNP genotype combination analysis further showed that genetic variation within representative candidate regions was significantly associated with flowering-time differences and vernalization-type differentiation. Predictive modeling indicated that candidate markers selected by GWAS and machine learning showed predictive potential within the present population. Overall, this study prioritized a set of GWAS- and ML-supported candidate regions and putative candidate genes associated with flowering time in B. napus from the complementary perspectives of statistical association and machine learning-based predictive contribution, providing candidate resources for future marker development, functional validation, and adaptive improvement in rapeseed.