Active O-acetylserine-(thiol) lyase A and B confer improved selenium resistance and degrade l-Cys and l-SeCys in Arabidopsis.

The roles of cytosolic O-acetylserine-(thiol)-lyase A (OASTLA), chloroplastic OASTLB, and mitochondrial OASTLC in plant selenate resistance were studied in Arabidopsis. Impairment in OASTLA and OASTLB resulted in reduced biomass, chlorophyll and soluble protein content compared with selenate-treated OASTLC-impaired and wild-type plants. The generally lower total selenium (Se), protein-Se, organic-sulfur and protein-sulfur (S) content in oastlA and oastlB compared with wild-type and oastlC leaves indicated that Se accumulation was not the main cause for the stress symptoms in these mutants. Notably, the application of selenate positively induced S-starvation markers and the OASTLs, followed by increased sulfite reductase, sulfite oxidase activities, and increased sulfite and sulfide concentrations. Taken together, our results indicate a futile anabolic S-starvation response that resulted in lower glutathione and increased oxidative stress symptoms in oastlA and oastlB mutants. In-gel assays of l-cysteine and l-seleno-cysteine, desulfhydrase activities revealed that two of the three OASTL activity bands in each of the oastl single mutants were enhanced in response to selenate, whereas the impaired proteins exhibited a missing activity band. The absence of differently migrated activity bands in each of the three oastl mutants indicates that these OASTLs are major components of desulfhydrase activity, degrading l-cysteine and l-seleno-cysteine in Arabidopsis.

Chickpea glutaredoxin (CaGrx) gene mitigates drought and salinity stress by modulating the physiological performance and antioxidant defense mechanisms.

Glutaredoxins (Grxs) are short, cysteine-rich glutathione (GSH)-mediated oxidoreductases. In this study, a chickpea (Cicer arietinum L.) glutaredoxin [LOC101493651 (CaGrx)] gene has been selected based on screening experiments with two contrasting varieties of chickpea, PUSA-362 (drought-tolerant) and ICC-1882 (drought-sensitive) under drought and salinity. The tolerant variety showed higher CaGrx gene expression, as compared to less in the sensitive variety, under both the stresses. The CaGrx gene was then over-expressed in Arabidopsis thaliana and were exposed to drought and salinity. The over-expression of CaGrx elevated the activity of glutaredoxin, which induced antioxidant enzymes (glutathione reductase; GR, glutathione peroxidase; GPX, catalase; CAT, ascorbate peroxidase; APX, glutathione-S-transferase; GST, superoxide dismutase; SOD, monodehydroascorbate reductase; MDHAR, and dehydroascorbate reductase; DHAR), antioxidants (GSH and ascorbate) and stress-responsive amino acids (cysteine and proline). Enhancement in the antioxidant defense system possibly administered tolerance in transgenics against both stresses. CaGrx reduced stress markers (H2O2, TBARS, and electrolyte leakage) and enhanced root growth, seed germination, and survival against both stresses. The physiological parameters (net photosynthesis; P N, water use efficiency; WUE, stomatal conductance; g s, transpiration; E, electron transport rate; ETR, and photochemical quenching; qP), chlorophylls and carotenoids, were improved in the transgenics during both stresses, that maintained the photosynthetic apparatus and protected the plants from damage. The enhanced activity of the cysteine biosynthesis enzyme, o-acetylserine (thiol) lyase (OAS-TL), increased the cysteine level in the transgenics, which elevated glutathione biosynthesis to maintain the ascorbate-glutathione cycle under both stresses. This investigation verified that the CaGrx gene provides tolerance against salinity and drought, maintaining physiological and morphological performances, and could be exploited for genetic engineering approaches to overcome both the stresses in various crops. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s12298-021-00999-z.

Over-expression of chickpea metallothionein 1 gene confers tolerance against major toxic heavy metal stress in Arabidopsis.

Heavy metals are ubiquitously present in nature, including soil, water, and thus in plants, thereby causing a potential health risk. This study has investigated the role and efficiency of the chickpea metallothionein 1 (MT1) gene against the major toxic heavy metals, i.e., As [As(III) and As(V)], Cr(VI), and Cd toxicity. MT1 over-expressing transgenic lines had reduced As(V) and Cr(VI) accumulation, whereas Cd accumulation was enhanced in the L3 line. The physiological responses (WUE, A, Gs, E, ETR, and qP) were noted to be enhanced in transgenic plants, whereas qN was decreased. Similarly, the antioxidant molecules and enzymatic activities (GSH/GSSG, Asc/DHA, APX, GPX, and GRX) were higher in the transgenic plants. The activity of antioxidant enzymes, i.e., SOD, APX, GPX, and POD, were highest in the Cd-treated lines, whereas higher CAT activity was observed in As(V)-L1 and GRX in Cr-L3 line. The stress markers TBARS, H2O2, and electrolyte leakage were lower in transgenic lines in comparison to WT, while RWC was enhanced in the transgenic lines, and the transcript of MT1 gene was accumulated in the transgenic lines. Similarly, the level of stress-responsive amino acid cysteine was higher in transgenic plants as compared to WT plants. Among all the heavy metals, MT1 over-expressing lines showed a highly increased accumulation of Cd, whereas a non-significant effect was observed with As(III) treatment. Overall, the results demonstrate that Arabidopsis thaliana transformed with the MT1 gene mitigates heavy metal stress by regulating the defense mechanisms in plants. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s12298-021-01103-1.

Selenite supplementation reduces arsenate uptake greater than phosphate but compromises the phosphate level and physiological performance in hydroponically grown Oryza sativa L.

The present study evaluates the reduction of arsenate (As[V]) uptake in rice seedlings through individual and combined supplementation of phosphate (PO4(3-)) and selenite (Se[IV]) in a hydroponic condition. The toxic response in seedlings receiving As(V) manifested as inhibition in physiological parameters such as water use efficiency, stomatal conductance, photosynthetic assimilation rate, transpiration rate, photochemical quenching, and electron transport rate, along with growth. Arsenic accumulation significantly decreased with Se(IV) treatment (0.5 µg mL(-1), 1 µg mL(-1), and 2 µg mL(-1)) in a dose-dependent manner (20%, 35%, and 53%, respectively); however, it compromised the PO4(3-) level and physiological performance. The lower level of Se(IV), (0.5 µg mL(-1)), was relatively beneficial in terms of reduction in As accumulation than the higher level of Se(IV), (2 µg mL(-1)), which was rather toxic. Further, decrease in As uptake, replenished the level of PO4(3-) and physiological performance in seedlings treated with As+Se+P compared with those treated with As+Se. However, supplementation with only PO4(3-) (10 µg mL(-1) and 20 µg mL(-1)) along with As(V) was less effective in reducing As accumulation compared with As+Se. Seedlings receiving As+Se+P also exhibited lower thiobarbituric acid-reactive substances (TBARS) and electrical conductivity levels compared with both As+Se and As+P. Among all the treatments, the activity of antioxidant enzymes was highest in plants treated with As+Se+P. Hence, the higher antioxidant enzyme activity in As+Se+P along with lower levels of TBARS, H2 O2 , and As accumulation are attributed to the competitive reduction in As uptake in the presence of Se(IV) and PO4(3-).

Comparative clinical efficacy of Ashtangavaleha and Vyaghreehareetakee Avaleha on Tamaka Shwasa (bronchial asthma) in children.

BACKGROUND: Tamaka Shwasa is a chronic inflammatory condition of the lung airways resulting in episodic airflow obstruction. This disease is more predominant in children and aged population. Apart from being the leading cause of hospitalization for children, it is one of the most important chronic conditions causing elementary school absenteeism. The parallel disease entity in contemporary medical science to this disorder is Bronchial Asthma. AIM: This study was aimed to evaluate the clinical efficacy of Ashtangavaleha and Vyaghreehareetakee Avaleha on Tamaka Shwasa (Bronchial Asthma) in Children. MATERIALS AND METHODS: The study was therapeutic interventional randomized clinical trial. Totally 100 patients suffering from Tamaka Shwasa were selected, and 74 patients completed the course of treatment. Patients were divided into two groups. Ashtangavaleha was administered in group AG and Vyaghreehareetakee Avaleha was administerd in group VG (5-15g in divided doses) for 8 weeks duration. Comaprative assesment of both the drugs was done on the signs and symptoms of the disease, pulmonary function test and quality of life parameters. RESULTS: When the individualized overall effect of therapy was considered, more number of patients treated with Ashtangavaleha reached moderate improvement zone than the patients treated with Vyaghreehareetakee Avaleha. CONCLUSIONS: The trial showed a marginal better efficacy of Ashtangavaleha (66.66%) in comparison to Vyaghreehareetakee Avaleha (63.15%) on the overall condition of the patients even though the superiority was statistically insignificant (>0.05).