Exploration of Culturable Marine Streptomyces from Southern Coastal Region of India with Antibacterial Properties

The Southern coastal region is a geographically positioned area with rich source of microbial diversity, of which producing broad spectrum of bioactive compounds. The marine sediments are collected from the various sites of south east coastal region of Tamil nadu and are processed. Out of 78 isolates, the 4 strains of actinomycetes are showing broad spectrum activity against Klebsiella pneumoniae (MTCC 1687), Proteus vulgaris (MTCC 3160), Salmonella typhi (MTCC 3231), Shigella dysenteriae (MTCC 3642) and Vibrio cholerae (MTCC 3906). The bioactive isolates are proceeded for further morphological features like growth pattern and mycelial coloration, biochemical and polyphasic taxonomical characterisation were documented. Isolates are investigated for abiotic stress condition to study the growth rate of isolates. Finally, the 16S rRNA molecular identification and phylogenetic analysis of the isolates were explored. Further, bioactive isolates may be potential source for discovery of molecules with industrial applications.

Proteomic analysis reveals different sets of proteins expressed during high temperature stress in two thermotolerant isolates of Trichoderma

Several species of the soil borne fungus of the genus Trichoderma are known to be versatile, opportunistic plant symbionts, and are the most successful biocontrol agents used in today's agriculture. To be successful in the field conditions, the fungus must endure varying climatic conditions. Studies have indicated that high atmospheric temperature coupled with low humidity is a major limitation for the inconsistent performance of Trichoderma under field conditions. Understanding the molecular modulation associated with such Trichoderma that persist and deliver under abiotic stress condition will aid in exploiting the worth of these organisms for such use. In this study, comparative proteomic analysis using two dimensional gel electrophoresis (2DE) and matrix assisted laser desorption/time of flight (MALDI-TOF-TOF) mass spectrometry was used to identify proteins associated with thermotolerance in two thermotolerant isolates of Trichoderma: T. longibrachiatum 673, TaDOR673 and T. asperellum 7316, TaDOR7316 and 32 differentially expressed proteins were identified. Sequence homology and conserved domains were used to identify these proteins and to assign probable function to them. Thermotolerant isolate, TaDOR673, seemed to employ the stress signaling MAPK pathways and heat shock response pathways to combat the stress condition whereas the moderately tolerant isolate, TaDOR7316, seemed to adapt to high temperature conditions by reducing the accumulation of misfolded proteins through unfolded protein response pathway and autophagy. Also, there were unique as well as common proteins that were differentially expressed in the two isolates studied.

Effect of sucrose on the fatty acid metabolism of adventitious root cultures in vitro of Stevia rebaudiana

In this study, the effect of sucrose on the neutral lipid profile of adventitious root cultures of Stevia rebaudiana was evaluated. The cultures were obtained employing a roller bottle system. In this system, Schott-type flasks were used, which contained Murashige and Skoog liquid medium at 33.3% strength (MS/3) supplemented with 30, 60, and 80 g L-1 of sucrose, respectively, and 10.7 mM 1-naphthaleneacetic acid (NAA). The spectroscopic analyzes showed that the portion of polyunsaturated fatty acids (PUFAs) was highest in roots treated with 30 g L-1 of sucrose. The spectrometric analyzes showed that the palmitic acid was found to be present in relatively higher amounts in the roots submitted to the MS/3-30 g L-1 (31.9%) and MS/3-60 g L-1 (29.5%) sucrose treatments, and lower in the treatment with MS/3-80 g L-1 (28.8%) of sucrose. Also, the treatment using 30 g L-1 of sucrose was the best for obtaining unsaturated fatty acids (UFAs) in the culture, with a relative percentage of 62.9%. Our results indicate that the MS medium that received 30 g L-1 of sucrose induced a lesser abiotic stress condition, which favored PUFAs production in the adventitious root cultures of S. rebaudiana.

The Effect of Low Temperature on Physiological, Biochemical and Flowering Functions of Olive Tree in Relation to Genotype

Olive tree growth and reproduction are severely affected by temperature extremes, compromising fruit yield. In that aspect, the olive varieties “Koroneiki” and “Mastoidis” were employed in a mild cold stress experiment, imitating night frost incidents to assess their biochemical, physiological and reproductive functions in relation to genotype. The physiological performance of the stressed plants was not significantly altered, suggesting that both cultivars were well adapted to mild cold night stress. The biochemical response of the plants, regarding antioxidant enzymes, H2O2 and TBARS accumulation, confirmed that both cultivars could cope with the stress applied. The mRNA levels of the PPO gene, which participates in hydroxytyrosol biosynthesis and plant defense, were elevated after 24-h stress at 0 °C, in both cultivars with “Mastoidis” plants exhibiting higher levels for a longer period. Three more genes involved in hydroxytyrosol biosynthesis upregulated their expression levels as a response to cold stress. The numerous plant phenology aspects measured reinforced the conclusion that both cultivars responded to the stress applied. The results of the present study may contribute to better understanding olive tree adaptive responses to low temperature events, an abiotic stress condition that is often present in an open plantation, thus assisting farmers on breeding and cultivar selection.

Role of nitric oxide in seed biology and seed production: A review

Nitric oxide (NO) is an important signalling molecule employed by plants to control many physiological aspects. This review summarizes that crosstalk between NO/H2O2/Ca2+ signalling pathways that drive pollen tube for sexual reproduction in flowering plants. NO is produced in seeds by both enzymatic and non-enzymatic sources that control many physiological aspects of seeds. The interplay of NO and Reactive oxygen species are likely important players in hormonal crosstalk controlling seed germination and dormancy. Mechanism of seed germination and dormancy is mainly regulated by plant hormones like Abscisic acid (ABA) and Gibberellic acid (GA). Based on mode of action of NO with reference to triggering the germination of crop seeds under abiotic stress condition it is infer that there is a linkage between NO and plant growth regulator production. NO cross-talk with reactive oxygen species (ROS) during abiotic stress condition, modulate the light and hormone depended developmental process in the early stage of plant development. NO action to enhancing abiotic stress tolerance by improving antioxidant enzymes and protection against oxidative damage in many crops are discussed in detail.