Hydrogen Sulfide: A Novel Gaseous Molecule for Plant Adaptation to Stress

Hydrogen sulfide (H₂S) has emerged as a novel gaseous signal molecule with multifarious effects on seed germination, plant growth, development, and physiological processes. Due to its dominant role in plant stress tolerance and cross-adaptation, it is getting more attention nowadays, although it has been largely referred as toxic and environmental hazardous gas. In this review work, we are highlighting the importance of H₂S as an essential gaseous molecule to help in signaling, metabolism, and stress tolerance in plants. Firstly, production of H₂S from different natural and artificial sources were discussed with its transformation from sulfur (S) to sulfate (SO₄²⁻) and then to sulfite (SO₃²⁻). The importance of different kinds of transporters that helps to take SO₄²⁻ from the soil solution was presented. Mainly, these transporters are SULTRs (H⁺/SO₄²⁻ cotransporters) and multigene family encodes them. Furthermore, these SULTRs have LAST (Low affinity transport proteins), HAST (High affinity transport proteins), vacuole transporters, and plastid transporters. Since it is well known that there is strong relationship between SO₄²⁻ and synthesis of hydrogen sulfide or dihydrogen sulfide or sulfane in plant cells. Thus, cysteine (Cys) metabolism through which H₂S could be generated in plant cell with the role of different enzymes has been presented. Furthermore, H₂S in interaction with other molecules could help to mitigate biotic and abiotic stress. Based on this review work, it can be concluded that H₂S has potential to induce cross-adaptation to biotic and abiotic stress; thus, it is recommended that it should be considered in future studies to answer the questions like what are the receptors of H₂S in plant cell, where in plants the physiological concentration of H₂S is high in response to multiple stress and how it induces cross-adaptation by interaction with other signal molecules.

     

Enhancement of resistance by poultry manure and plant hormones (salicylic acid & citric acid) against tobacco mosaic virus

Virus is the most menacing factor for plant, which causes enormous economic losses in agriculture worldwide. Tobacco mosaic virus is most hazardous virus among the plants that can spread through biological and non-biological sources. TMV is ancient virus that causes huge economic losses to pepper cucumber ornamental crops and tobacco. It can be controlled by reducing the population of vector through pesticide application. However, the rapid usage of synthetic chemicals causes environmental pollution and destroys our ecosystem. Consequently, different approaches just like natural derivatives should be adopted for the environmental friendly management for TMV. This in vitro study demonstrated the potential role of natural metabolites such as poultry manure and plant extracts such as salicylic acid and citric acid for the control of TMV. Two different concentrations of poultry manure 60G and 30G were used. Poultry manure was mixed with the soil at the time of sowing. Disease severity was minimum at maximum concentration as compared to the control. Meanwhile, two different concentrations of salicylic acid and citric acid 60% and 90% were applied by foliar sprayer after three-leaf stages. Disease severity was observed after 5, 10, 15, 20, 25, and 30 days after disease inoculation. Here also maximum concentration showed the minimum disease severity and higher concentration of both animal and plants extracts were used for following experiment. Quantitative real-time PCR (RT-qPCR) results demonstrated that different plant defense-related genes such as PR1a, PAL, PR5, NPR1, PRIb, and PDF1.2 were up-regulated. Furthermore, applications of each treatment-induced systemic resistance against a wide range of pathogen including TMV and fungal pathogen Botrytis cinerea.     

Activity of Fluorinated Curcuminoids against Leishmania major and Toxoplasma gondii Parasites

A new 3,4-difluorobenzylidene analog of curcumin, CDF, was recently reported, which demonstrated significantly enhanced bioavailability and in vivo anticancer activity compared with curcumin. For highlighting the antiparasitic behavior of CDF, we tested this compound together with its new O-methylated analog MeCDF against Leishmania major and Toxoplasma gondii parasites. Both CDF and MeCDF were tested in vitro against L. major and T. gondii. In addition, the in vitro cytotoxicity against Vero cells and macrophages was determined and selectivity indices were calculated. The DPPH radical scavenging activity assay was carried out in order to determine the antioxidant activity of the test compounds. Both compounds showed high activities against both parasite forms with EC₅₀ values in the (sub-)micromolar range (0.35 to 0.8 μM for CDF, 0.31 to 1.2 μM for MeCDF). The higher activity of CDF against L. major amastigotes when compared with MeCDF can in parts be attributed to the antioxidant activity of CDF while MeCDF lacking any antioxidant activity was more active than CDF against T. gondii parasites. In conclusion, CDF and MeCDF are promising antiparasitic drug candidates due to their high activities against L. major and T. gondii parasites.     

Effect of gibberellic acid on the vase life and oxidative activities in senescing cut gladiolus flowers

Cut flowers face the problem of short display life and lose their aesthetic value rapidly. In order to enhance the vase life of gladiolus, its cut spikes were subjected to different levels of gibberellic acid (GA₃), viz., 0, 25, 50, 100 and 200 mg L^?1 in vase solution, during two consecutive years 2010 and 2011. The GA₃ treatment significantly influenced the vase quality attributes and antioxidants capacity of gladiolus cut flowers. Gibberellic acid at 25 mg L^?1 caused the longest time taken to open the floret and increased the floret opening, vase life duration and fresh weight. The highest antioxidative activities of superoxide dismutase and free radicals scavenging were also recorded with GA₃ at 25 mg L^?1. The highest peroxidase, catalase activity and the lowest membrane leakage were recorded with GA₃ at 50 mg L^?1. Present study concludes that GA₃ applied at lower concentrations (25 mg L^?1) renders greater beneficial effects on vase life quality, membrane stability and antioxidant activities in gladiolus cut spike, and further higher application rates cause no improvement in the flower longevity.     

Autosomal Recessive Transmission of a Rare KRT74 Variant Causes Hair and Nail Ectodermal Dysplasia: Allelism with Dominant Woolly Hair/Hypotrichosis

Pure hair and nail ectodermal dysplasia (PHNED) comprises a heterogeneous group of rare heritable disorders characterized by brittle hair, hypotrichosis, onychodystrophy and micronychia. Autosomal recessive (AR) PHNED has previously been associated with mutations in either KRT85 or HOXC13 on chromosome 12p11.1-q14.3. We investigated a consanguineous Pakistani family with AR PHNED linked to the keratin gene cluster on 12p11.1 but without detectable mutations in KRT85 and HOXC13. Whole exome sequencing of affected individuals revealed homozygosity for a rare c.821T>C variant (p.Phe274Ser) in the KRT74 gene that segregates AR PHNED in the family. The transition alters the highly conserved Phe274 residue in the coil 1B domain required for long-range dimerization of keratins, suggesting that the mutation compromises the stability of intermediate filaments. Immunohistochemical (IHC) analyses confirmed a strong keratin-74 expression in the nail matrix, the nail bed and the hyponychium of mouse distal digits, as well as in normal human hair follicles. Furthermore, hair follicles and epidermis of an affected family member stained negative for Keratin-74 suggesting a loss of function mechanism mediated by the Phe274Ser substitution. Our observations show for the first time that homozygosity for a KRT74 missense variant may be associated with AR PHNED. Heterozygous KRT74 mutations have previously been associated with autosomal dominant woolly hair/hypotrichosis simplex (ADWH). Thus, our findings expand the phenotypic spectrum associated with KRT74 mutations and imply that a subtype of AR PHNED is allelic with ADWH.     

Characterization of <Emphasis Type="Italic">VvPAL-like</Emphasis> promoter from grapevine using transgenic tobacco plants

A 2000-bp 5′-flanking region of VvPAL-like was isolated from ‘Summer Black’ grapevine by PCR amplification, named pVvPAL-like. To gain a better understanding of the expression and regulatory mechanism of VvPAL-like, a chimeric expression unit consisting of the β-glucuronidase (GUS) reporter gene under the control of a 2000-bp fragment of the VvPAL-like promoter was transformed into tobacco via Agrobacterium tumefaciens. Histochemical staining showed that the full-length promoter directs efficient expression of the reporter gene in cotyledons and hypocotyls, stigma, style, anthers, pollen, ovary, trichomes, and vascular bundles of transgenic plants. A series of 5′ progressive deletions of the promoter revealed the presence of a negative regulatory region (?424 to ?292) in the VvPAL-like promoter. Exposure of the transgenic tobacco plants to various abiotic stresses demonstrated that the full-length construct could be induced by light, copper (Cu), abscisic acid (ABA), indole-3-acetic (IAA), methyl jasmonate (MeJA) (N-1-naphthylphthalamic acid), ethylene, and drought. Furthermore, the ethylene-responsive region was found to be located in the ?1461/?930 fragment, while the element(s) for the MeJA-responsive expression may be present in the ?424/?292 region in the VvPAL-like promoter. These findings will help us to better understand the molecular mechanisms by which VvPAL-like participates in biosynthesis of flavonoids and stress responses.     

Changes in Body Wall of Sea Cucumber (<Emphasis Type="Italic">Stichopus japonicus</Emphasis>) during a two-Step Heating Process Assessed by Rheology,LF-NMR,and Texture Profile Analysis

Sea cucumber (Stichopus japonicus) is regarded as a highly priced delicacy in Japan and China owing to its unique elasticity and palatability. Heating is an essential step to process sea cucumber with desired texture. In the present study, sea cucumber body wall was pre-heated at 40 °C, followed by post-heating at 80 °C. Changes in body wall were assessed by rheology, LF-NMR, and texture profile analysis. The small strain rheological analysis indicated that there were significant structural changes of body wall at about 40 °C during pre-heating. Large strain texture profile analysis and the storage modulus showed a good correlation. LF-NMR analysis displayed only one water population in samples pre-heated at 40 °C for up to 120 min, and the population did not change significantly with the heating duration. This demonstrated that structural changes and moisture loss from the inter collagen fibrils were not significant. As for samples post-heated at 80 °C, three distinct peaks were found and the T ₂ relaxation time and area of the bulk water decreased significantly, revealing significant changes of internal structures and loss of water-holding capacity. T ₂ parameters had a good correlation to texture profile analysis parameters for samples after both pre-heating and post-heating.     

Inhibiting Tyrosine Phosphorylation of Protein Kinase Cδ (PKCδ) Protects the Salivary Gland from Radiation Damage

Radiation therapy for head and neck cancer can result in extensive damage to normal adjacent tissues such as the salivary gland and oral mucosa. We have shown previously that tyrosine phosphorylation at Tyr-64 and Tyr-155 activates PKCδ in response to apoptotic stimuli by facilitating its nuclear import. Here we have identified the tyrosine kinases that mediate activation of PKCδ in apoptotic cells and have explored the use of tyrosine kinase inhibitors for suppression of irradiation-induced apoptosis. We identify the damage-inducible kinase, c-Abl, as the PKCδ Tyr-155 kinase and c-Src as the Tyr-64 kinase. Depletion of c-Abl or c-Src with shRNA decreased irradiation- and etoposide-induced apoptosis, suggesting that inhibitors of these kinases may be useful therapeutically. Pretreatment with dasatinib, a broad spectrum tyrosine kinase inhibitor, blocked phosphorylation of PKCδ at both Tyr-64 and Tyr-155. Expression of “gate-keeper” mutants of c-Abl or c-Src that are active in the presence of dasatinib restored phosphorylation of PKCδ at Tyr-155 and Tyr-64, respectively. Imatinib, a c-Abl-selective inhibitor, also specifically blocked PKCδ Tyr-155 phosphorylation. Dasatinib and imatinib both blocked binding of PKCδ to importin-α and nuclear import, demonstrating that tyrosine kinase inhibitors can inhibit nuclear accumulation of PKCδ. Likewise, pretreatment with dasatinib also suppressed etoposide and radiation induced apoptosis in vitro. In vivo, pre-treatment of mice with dasatinib blocked radiation-induced apoptosis in the salivary gland by >60%. These data suggest that tyrosine kinase inhibitors may be useful prophylactically for protection of nontumor tissues in patients undergoing radiotherapy of the head and neck.     

Phylogenetic analysis of Aedes species distributed in Taif Province,Saudi Arabia,based on mitochondrial COX1 sequences

As Aedes mosquitoes are the predominant carriers of arboviruses responsible for global dengue fever and chikungunya outbreaks, understanding their genetic diversity and population structure can enhance dengue prevention and vector control efforts. Although sympatric cryptic species have been acknowledged in Aedes species subgroups in Southeast Asia, little information is available regarding the occurrence and dispersal of cryptic Aedes species in Saudi Arabia. In the present investigation, we intend to analyze genetic variations and perform a phylogenetic study of sympatric Aedes samples collected from various locations in Taif Province, Saudi Arabia. The locus of mitochondrial DNA cytochrome c oxidase subunit 1 (COX1, analyzed with DNA barcoding) was utilized to determine genetic variance and to build phylogenetic trees. For species identification, the COX1 sequences of Aedes samples from Taif Province were compared with those of Aedes samples from GenBank (National Center for Biotechnology Information, NCBI). To identify phylogenetic relationships and genetic variability, phylogenetic trees were created using Taif Province samples, GenBank A. albopictus samples, and GenBank A. aegypti samples. The phylogenetic analysis revealed that some Taif samples (A3, A7, F2, F4, F1, A4, A1, F9 and F6) were closer to A. aegypti and A. albopictus samples from Africa and East Asia, especially Kenya and Malaysia. Whereas other samples (F9, F6, A4, F1 and A1) were closer to the GenBank A. aegypti samples KP843383 (Thailand), HM399357(Australia), MK533632 (Kenya), KX420460 (Kenya), KU495081 (Australia) and MF179160 (China) than the remaining Taif samples. Overall, our findings demonstrate that examining the genetic diversity and phylogenetic linkages of Aedes samples can aid in understanding the evolution of Aedes cryptic species in the western regions of Saudi Arabia.