Enhanced In Vitro Plant Morphogenesis of Tobacco: Unveiling Indoleamine-Modulated Adaptogenic Properties of Tulsi (Ocimum sanctum L.).

The medicinal plant tulsi (Ocimum sanctum L.) is acknowledged for its invigorating and healing properties that enhance resilience to stress in various human and animal models by modulating antioxidant compounds. While extensive research has documented these effects in humans, the adaptogenic potential of tulsi in stressful in vitro plant systems has not been explored. This study aimed to elucidate the adaptogenic properties of tulsi leaf extract on the in vitro regeneration of tobacco leaf explants through an investigation of the indoleamines at different developmental stages. Shoot regeneration from leaf explants on the medium supplemented with tulsi extract (20%) was compared to the control, and the differences in indoleamine compounds were analyzed using ultra-performance liquid chromatography. Treatment of the explants with the extract resulted in an almost two-fold increase in the number of regenerants after four weeks of culture, and 9% of the regenerants resembled somatic embryo-like structures. The occurrence of browning in the extract-treated explants stopped on day 10, shoots began to develop, and a significant concentration of tryptamine and N-acetyl-serotonin accumulated. A comparative analysis of indoleamine compounds in intact and cut tobacco leaves also revealed the pivotal role of melatonin and 2-hydroxymelatonin functioning as antioxidants during stress adaptation. This study demonstrates that tulsi is a potent adaptogen that is capable of modulating plant morphogenesis in vitro, paving the way for further investigations into the role of adaptogens in plant stress biology.

Preharvest Spray Hexanal Formulation Enhances Postharvest Quality in 'Honeycrisp' Apples by Regulating Phospholipase D and Calcium Sensor Proteins Genes.

'Honeycrisp' (Malus domestica Borkh.), a premium applecultivar, is highly susceptible to bitter pit and decline in quality during long-term storage. In order to enhance the quality, an aqueous composition containing hexanal was applied as a preharvest spray. The effects of hexanal were assessed on the treated fruit and compared with HarvistaTM (a sprayable 1-Methylcyclopropene based commercial formulation) applied and control fruit under both cold (2.5 °C; four months) and cold after room temperature storage (20 °C; 14 days) conditions. Color, firmness, and total soluble solids (TSS) did not show a significant change in response to any treatment at harvest, while abscisic acid (ABA) significantly reduced and tryptophan increased in response to hexanal, compared to HarvistaTM and control. The treatment effects on quality traits were observed during storage. Both hexanal and HarvistaTM sprayed apples had higher TSS under both cold and room temperature storage. In addition, both sprays enhanced firmness at room temperature storage. However, the effects of sprays on other quality traits showed a different pattern. Apples sprayed with hexanal had lower phospholipase D enzyme (PLD) activity, lower incidence of bitter pit, and decreased expression of MdPLDα1 compared to HarvistaTM and control. On the other hand, HarvistaTM treated fruit produced lower ethylene. Both sprays decreased the expression of MdPLDα4, MdCaM2, MdCaM4 and MdCML18 genes. Generally, PLD alpha has a direct role in promoting fruit senescence, whereas the calcium senor proteins (CaM/CMLs) may involve in fruit ripening process via calcium and ethylene interactions. Therefore, improved postharvest qualities, including the lower incidence of bitter pit in hexanal treated 'Honeycrisp', may be associated with lower membrane damage due to lower PLD enzyme activity and decreased expression of MdPLDα1 and MdPLDα4 genes throughout the storage period.

Transcriptomics of Improved Fruit Retention by Hexanal in 'Honeycrisp' Reveals Hormonal Crosstalk and Reduced Cell Wall Degradation in the Fruit Abscission Zone.

Apples (Malus domestica Borkh) are prone to preharvest fruit drop, which is more pronounced in 'Honeycrisp'. Hexanal is known to improve fruit retention in several economically important crops. The effects of hexanal on the fruit retention of 'Honeycrisp' apples were assessed using physiological, biochemical, and transcriptomic approaches. Fruit retention and fruit firmness were significantly improved by hexanal, while sugars and fresh weight did not show a significant change in response to hexanal treatment. At commercial maturity, abscisic acid and melatonin levels were significantly lower in the treated fruit abscission zone (FAZ) compared to control. At this stage, a total of 726 differentially expressed genes (DEGs) were identified between treated and control FAZ. Functional classification of the DEGs showed that hexanal downregulated ethylene biosynthesis genes, such as S-adenosylmethionine synthase (SAM2) and 1-aminocyclopropane-1-carboxylic acid oxidases (ACO3, ACO4, and ACO4-like), while it upregulated the receptor genes ETR2 and ERS1. Genes related to ABA biosynthesis (FDPS and CLE25) were also downregulated. On the contrary, key genes involved in gibberellic acid biosynthesis (GA20OX-like and KO) were upregulated. Further, hexanal downregulated the expression of genes related to cell wall degrading enzymes, such as polygalacturonase (PG1), glucanases (endo-ß-1,4-glucanase), and expansins (EXPA1-like, EXPA6, EXPA8, EXPA10-like, EXPA16-like). Our findings reveal that hexanal reduced the sensitivity of FAZ cells to ethylene and ABA. Simultaneously, hexanal maintained the cell wall integrity of FAZ cells by regulating genes involved in cell wall modifications. Thus, delayed fruit abscission by hexanal is most likely achieved by minimizing ABA through an ethylene-dependent mechanism.

Acquired salinity tolerance in rice: Plant growth dataset.

This article describes the growth of 18 acclimatized and 11 non-acclimatized rice varieties grown in a hydroponic nutrient solution in a glasshouse. Four plants from each variety were grown under control conditions, salinity stress following control conditions (salinity), and salinity stress following acclimation (salinity/acclimation) conditions. Sampling was performed at the end of the salinity treatment (36 days of growth). Growth traits such as shoot and root biomass accumulation and lengths were measured for each variety, and the average was calculated using four replicates. This dataset may aid interested researchers in making comparisons with their data and further advance the research on the salinity acclimation process in rice.

Contribution of two different Na+ transport systems to acquired salinity tolerance in rice.

To elucidate the mechanisms of salt acclimation, physiological parameters of 70 rice varieties were compared under control and salt stress conditions after the acclimation treatment. The results indicated that some rice varieties had the ability to acclimatize to salt stress, exhibiting improved growth following the acclimation treatment under subsequent salinity stress compared to those without acclimation treatment. Conversely, some varieties exhibited reduced growth both with and without acclimation treatment under subsequent salinity stress. Acclimatized varieties had differential patterns of Na+ accumulation in the leaf blades because some varieties reduced Na+ accumulation under salinity stress, whereas others did not. Under salt stress, the acclimatized varieties with low Na+ accumulation in the leaf blades highly induced the expression of the OsHKT1;5 gene in the roots, which may contribute to Na+ exclusion from the shoots. On the other hand, the acclimatized varieties with high Na+ accumulation in the leaf blades exhibited higher induction of the OsNHX1 gene, whose gene product participates in the compartmentalization of Na+ into vacuoles. Thus, rice develops different mechanisms of salinity acclimation using two Na+ transport systems, and active regulation of Na+ transport at the transcription level may be involved in the salt acclimation process and enhance salinity tolerance.