Biosynthesis of capsaicinoids in pungent peppers under salinity stress.

The synthesis of capsaicinoids occurs in the placenta of the fruits of pungent peppers. However, the mechanism of capsaicinoids' biosynthesis in pungent peppers under salinity stress conditions is unknown. The Habanero and Maras genotypes, the hottest peppers in the world, were chosen as plant material for this study, and they were grown under normal and salinity (5 dS m-1 ) conditions. The results showed that salinity stress harmed plant growth but increased the capsaicin content by 35.11% and 37.00%, as well as the dihydrocapsaicin content by 30.82% and 72.89% in the fruits of the Maras and Habanero genotypes, respectively, at 30 days after planting. The expression analysis of key genes in capsaicinoids biosynthesis revealed that the PAL1, pAMT, KAS, and PUN1 genes were overexpressed in the vegetative and reproductive organs of pungent peppers under normal conditions. However, under salinity stress, overexpression of PAL1, pAMT, and PUN1 genes was identified in the roots of both genotypes, which was accompanied by an increase in capsaicin and dihydrocapsaicin content. The findings showed that salinity stress caused an enhancement in the capsaicin and dihydrocapsaicin contents in the roots, leaves, and fruits of pungent peppers. Nonetheless, it was found that the production of capsaicinoids is generally not restricted to the fruits of pungent peppers.

Genetic Analysis in Grain Legumes [Vigna radiata (L.) Wilczek] for Yield Improvement and Identifying Heterotic Hybrids.

Six mungbean parental lines and their fifteen F1s produced from half-diallel mating design were investigated for combining ability and heterosis in terms of a yield and its components. Results showed highly significant variations among the parents and F1s, suggesting a wide genetic variability for the studied characters. Analysis of variance indicated that genotypes mean square values, general combining ability (GCA) and specific combining ability (SCA) were highly significant (p ≤ 0.001) for all measured traits except for days to flowering, days to maturity, and pod length indicating genetic diversity of parents and both additive and non-additive gene effects in the inheritance of the measured traits. A higher effect of SCA than GCA for plant height and seeds per pod suggests the preponderance of non-additive gene effects in the expression of characters. Based on per se performance and GCA, BARI Mung-1, PS-7, and BMXK1-14004 were the best general combiners for yield per plant. In the context of SCA, hybrids BMXK1-14004 × Sonali mung, BMXK1-14004 × PS-7, BMXK1-14004 × BINA Mung-8, Sukumar × PS-7, and BARI Mung-1 × BINA Mung-8 were good specific combiners. BMXK1-14004 × Sonali mung and BMXK1-14004 × PS-7 were the best heterotic hybrids for yield and yield-contributing traits. These parents and crosses could be utilized for further use in breeding programs to improve yields in mungbean crops.

Mitigation of salinity stress in cucumber seedlings by exogenous hydrogen sulfide.

This research hypothesized that tolerance of cucumber seedlings to salinity stress could be increased by hydrogen sulfide (H2S) treatments. In pot experiments, the cucumber seedlings were exposed to three levels of salt stress (0, 50 and 100 mM NaCl), and NaHS as H2S donor was foliar applied to the cucumber seedlings at five different doses (0, 25, 50, 75 and 100 µM). The effects of the treatments on cucumber seedlings were tested with plant growth properties as well as physiological and biochemical analyses. As the salinity level increased, plant growth properties and chlorophyll reading value (SPAD) decreased. However, H2S treatments significantly mitigated the impact of salinity. Salt stress elevated the membrane permeability (MP) and decreased the leaf relative water content (LRWC). H2S applied leaves had lower MP and higher LRWC than non-H2S applied leaves. On the other hand, photosynthetic properties (net photosynthetic rate, stomatal conductance, transpiration rate and intercellular CO2 concentration) of the seedlings under salt stress conditions were decreased but this decrease was considerably relieved by H2S treatment. The K/Na and Ca/Na ratios under salt stress conditions were higher in H2S-applied plants than in non-applied plants. Furthermore, antioxidant enzyme activity [(catalase (CAT), peroxidase (POD) and superoxide dismutase (SOD)] and hydrogen peroxide (H2O2), malondialdehyde (MDA), proline, and sucrose concentration in the leaves increased with salinity stress whereas they were reduced with H2S treatments under salt stress. Mitigation of salt stress damage in cucumber using H2S treatment can be expounded via modulation of enzyme activity, nutrient content, reactive oxygen species (ROS) formation, and osmolytes accumulation.

Humic + Fulvic acid mitigated Cd adverse effects on plant growth, physiology and biochemical properties of garden cress.

Cadmium (Cd) is a toxic and very mobile heavy metal that can be adsorbed and uptaken by plants in large quantities without any visible sign. Therefore, stabilization of Cd before uptake is crucial to the conservation of biodiversity and food safety. Owing to the high number of carboxyl and phenolic hydroxyl groups in their structure, humic substances form strong bonds with heavy metals which makes them perfect stabilizing agents. The aim of this study was to determine the effects of humic and fulvic acid (HA + FA) levels (0, 3500, 5250, and 7000 mg/L) on alleviation of Cadmium (Cd) toxicity in garden cress (Lepidium sativum) contaminated with Cd (CdSO4.8H2O) (0, 100, and 200 Cd mg/kg) under greenhouse conditions. Our results showed that, Cd stress had a negative effect on the growth of garden cress, decreased leaf fresh, leaf dry, root fresh and root dry weights, leaf relative water content (LRWC), and mineral content except for Cd, and increased the membrane permeability (MP) and enzyme (CAT, SOD and POD) activity. However, the HA + FA applications decreased the adverse effects of the Cd pollution. At 200 mg/kg Cd pollution, HA + FA application at a concentration of 7000 mg/L increased the leaf fresh, leaf dry, root fresh, root dry weights, stem diameter, leaf area, chlorophyll reading value (CRV), MP, and LRWC values by 262%, 137%, 550%,133%, 92%, 104%, 34%, 537%, and 32% respectively, compared to the control. Although the highest H2O2, MDA, proline and sucrose values were obtained at 200 mg/L Cd pollution, HA + FA application at a concentration of 7000 mg/L successfully alleviated the deleterious effects of Cd stress by decreasing H2O2, MDA, proline, and sucrose values by 66%, 68%, 70%, and 56%, respectively at 200 mg/kg Cd pollution level. HA + FA application at a concentration of 7000 mg/L successfully mitigated the negative impacts of Cd pollution by enhanced N, P, K, Ca, Mg, Fe, Mn, Cu, Mn, Zn, and B by 75%, 23%, 84%, 87%, 40%, 85%, 143%, 1%, 65%, and 115%, respectively. In addition, HA + FA application at a concentration of 7000 mg/L successfully reduced Cd uptake by 95% and Cl uptake by 80%. Considering the plant growth parameters, the best results were determined when HA + FA concentration was 7000 mg/L. We have shown that, it is critical to apply a humic substance with high percentage of FA, which was 10% in this study, to mitigate the adverse effects of heavy metal stress on plant growth. In conclusion, the application of HA + FA may be suggested as an effective solution for reducing the Cd uptake of the plants by stabilizing Cd in soil and preventing translocation of Cd from the roots of plant to its shoot and leaves.

Nitric oxide mitigates salt stress effects of pepper seedlings by altering nutrient uptake, enzyme activity and osmolyte accumulation.

This study was planned to evaluate the role of exogenous application of sodium nitroprusside (SNP), a NO donor, on the deleterious effect of salinity in Capsicum annum L. seedlings. Different NO doses (0, 50, 100 and 150 µM SNP) were foliarly applied to pepper seedlings grown under the non-saline and saline conditions (50, 100 and 150 mM of NaCl). The photosynthetic rate (Pn), stomatal conductance (gs), intercellular CO2 concentration (Ci), transpiration rate (Tr), mineral element (Zn, Fe, B, K, Ca and Mg) uptake, plant growth and leaf relative water content (LRWC) were decreased by NaCl treatment, but NO treatments generally improved the observed parameters. 150 mM NaCl treatment caused overaccumulation of hydrogen peroxide (H2O2) and malondialdehyde (MDA) by 87 and 100% respectively as compared to control. However, NO application (150 µM SNP) at 150 mM of NaCl significantly decreased H2O2 and MDA to 34 and 54%, respectively. The present study clarified that the exogenous NO treatment supported pepper seedlings against salinity stress by regulating the mineral nutrient uptake, antioxidant enzyme activity, osmolyte accumulation, and improving the LRWC and photosynthetic activity.