Hydrogen sulphide-mediated alleviation and its interplay with other signalling molecules during temperature stress.

The sessile habit of plants does not provide choices to escape the environmental constraints, leading to negative impacts on their growth and development. This causes significant losses in the agriculture sector and raises serious issues on global food security. Extreme temperatures (high or low) influence several aspects of plant life and can cause reproduction malfunction. Therefore, a strategy for temperature amelioration is necessary for the management of agricultural productivity. Supplementation with various chemicals (e.g. phytohormones, gasotransmitters, osmolytes) is considered a good choice to manage plant stress. Gasotransmitters are well-recognized for stress mitigation in plants, among which hydrogen sulphide (H2 S) has proved promising to alleviate stress. Temperature (heat/cold) stress can stimulate the endogenous production of H2 S in plants, and many studies have reported the significance of H2 S for temperature stress amelioration. Here, H2 S led to positive changes in plant physiological, biochemical and molecular responses, which are usually compromised during stress. Further, H2 S also coordinate with other signalling components that act either upstream or downstream during stress mitigation. This review focuses on the significance of H2 S for mitigation of temperature stress, with a comprehensive discussion on cross-talk with other signalling components or supplements (e.g. NO, H2 O2 , salicylic acid, trehalose, proline). Finally, the review provides a rational assessment and holistic understanding of H2 S-mediated mitigation of extreme temperature stress and addresses the prospects for development of an effective strategy to manage temperature stress.

Influence of root-knot nematode infestation on antioxidant enzymes, chlorophyll content and growth in Pogostemon cablin (Blanco) Benth.

Plants adapt themselves to overcome adverse environmental conditions, and this involves a plethora of concurrent cellular activities. Physiological experiments or metabolic profiling can quantify this response. Among several diseases of Pogostemon cablin (Blanco) Benth. (Patchouli), root-knot nematode infection caused by Meloidogyne incognita (Kofoid and White) Chitwood causes severe damage to the plant and hence, the oil production. In the present study, we identified M. incognita morphologically and at molecular level using sequenced characterized amplified region marker (SCAR). M. incognita was artificially inoculated at different levels of second stage juveniles (J2) to examine the effect on Patchouli plant growth parameters. Peroxidase and polyphenol oxidase enzyme activity and changes in the total phenol and chlorophyll contents in M. incognita was also evaluated in response to infection. The results have demonstrated that nematode infestation leads to increased peroxidase activities in the leaves of the patchouli plants and thereby, increase in phenolic content as a means of defence against nematode infestation. Chlorophyll content was also found decreased but no changes in polyphenol oxidase enzyme activity.

Development of an effective and efficient DNA isolation method for Cinnamomum species.

Different species of Cinnamomum are rich in polysaccharide's and secondary metabolites, which hinder the process of DNA extraction. High quality DNA is the pre-requisite for any molecular biology study. In this paper we report a modified method for high quality and quantity of DNA extraction from both lyophilized and non-lyophilized leaf samples. Protocol reported differs from the CTAB procedure by addition of higher concentration of salt and activated charcoal to remove the polysaccharides and polyphenols. Wide utility of the modified protocol was proved by DNA extraction from different woody species and 4 Cinnamomum species. Therefore, this protocol has also been validated in different species of plants containing high levels of polyphenols and polysaccharides. The extracted DNA showed perfect amplification when subjected to RAPD, restriction digestion and amplification with DNA barcoding primers. The DNA extraction protocol is reproducible and can be applied for any plant molecular biology study.

A highly efficient in vitro propagation protocol for elephant tusk cactus: Coryphantha elephantidens (Lem.) Lem.

BACKGROUND: Elephant tusk cactus Coryphantha elephantidens (Lem.) Lem. is an important attractive ornamental cactus. The plant produces offshoots from tubercles very rarely, and the seedlings exhibit slow growth and susceptibility to damping off. Slow growth and high demand in the cactus industry lead to finding an alternate fast propagation method. RESULTS: An innovative in vitro technique based on axillary bud proliferation has been developed for an ornamental cactus C. elephantidens (Lem.) Lem. Four different explant types formed multiple shoots on Murashige and Skoog (MS) medium. Of the two cytokinins, 6-Benzylaminopurine (BAP) and Kinetin (KN), BAP proved to be more effective for multiple shoot induction and shoot growth from different explant types. Longitudinally cut stem explants, when cultured on MS medium supplemented with 6.6 µM BAP give maximum axillary shoot proliferation (12.4 shoots). Type of explant significantly influenced the micropropagation rate. Type of carbon source used in the medium imparted a profound effect on shoot growth and dry weight. The maximum dry weight gain of the shoot was observed with 9% sucrose. CONCLUSION: Development of an efficient micropropagation protocol which can be used to produce more than 10,000 rooted plantlets in 150 days from a single longitudinally divided shoot explant.

High gene flow and genetic diversity in three economically important Zanthoxylum Spp. of Upper Brahmaputra Valley Zone of NE India using molecular markers.

The genetic diversity in Zanthoxylum species viz.  Zanthoxylum nitidum, Zanthoxylum oxyphyllum and Zanthoxylum rhesta collected from the Upper Brahmaputra Valley Zone of Assam (NE India) was amplified using 13 random amplified polymorphic DNA (RAPD) markers and 9 inter-simple sequence repeat (ISSR) markers. RAPD markers were able to detect 81.82% polymorphism whereas ISSR detected 98.02% polymorphism. The genetic similarities were analyzed from the dendrogram constructed by RAPD and ISSR fingerprinting methods which divided the 3 species of Zanthoxylum into 3 clear different clusters. The principle component analysis (PCA) was carried out to confirm the clustering pattern of RAPD and ISSR analysis. Analysis of molecular variance (AMOVA) revealed the presence of significant variability between different Zanthoxylum species and within the species by both RAPD and ISSR markers. Z. nitidum was found to be sharing a high degree of variation with the other two Zanthoxylum species under study. The Nei's gene diversity (h), Shannon's information index (I), observed number of alleles (na) and effective number of alleles (ne) were also found to be higher in ISSR markers (0.3526, 0.5230, 1.9802 and 1.6145) than in RAPD markers (0.3144, 0.4610, 1.8182 and 1.5571). The values for total genotype diversity for among population (HT), within population diversity (Hs) and gene flow (Nm) were more in ISSR (0.3491, 0.2644 and 1.5610) than RAPD (0.3128, 0.2264 and 1.3087) but the mean coefficient of gene differentiation (GST) was more in RAPD (0.2764) than ISSR (0.2426). A comparison of this two finger printing methods was done by calculating MR, EMI and MI. The correlation coefficient between data matrices of RAPD and ISSR based on Mantel test was found to be significant (r = 0.65612).

Ty1-copia retrotransposon-based SSAP marker development in cashew (Anacardium occidentale L.).

The most popular retrotransposon-based molecular marker system in use at the present time is the sequence-specific amplification polymorphism (SSAP) system . This system exploits the insertional polymorphism of long terminal repeat (LTR) retrotransposons around the genome. Because the LTR sequence is used to design primers for this method, its successful application requires sequence information from the terminal region of the mobile elements . In this study, two LTR sequences were isolated from the cashew genome and used successfully to develop SSAP marker systems. These were shown to have higher levels of polymorphism than amplified fragment length polymorphic markers for this species.