Plant secondary biosynthetic pathways are exceedingly inducible by elicitors and facilitate enhanced metabolite production using plant cell tissue and organ cultures. Elicitors can regulate large number of control points and trigger the expression of key genes with increased cellular activities at biochemical and molecular level involving signal compounds. A large number of chemical elicitors viz: jasmonic acid (JA), methyl jasmonate (MeJA), salicylic acid (SA), acetyl salicylic acid (ASA), ethylene (ET) and ethrel (Ethe), heavy metals (HM), many types of chemical compounds (natural or synthetic) and their combinations are used for elicitation studies. Cell suspensions and hairy roots are commonly used culture systems followed by adventitious roots and multiple shoots for elicitation experiments. Amongst the elicitors and concentrations used 100 µM MeJA was found optimum for secondary metabolite enhancement in majority of experiments compared to SA and JA. Elicitor treatments promoted yield enhancements starting from 1.0 to maximum of 2230-fold across plant species studied. Elicitors singly with media additives, combination of elicitors and elicitors other than signal compounds along with hormones were found beneficial for enhanced secondary metabolite production. Further, a combination of target gene over expression and elicitor treatment also supported higher secondary product yield. The present communication presents information exclusively about the use of chemical elicitors for secondary metabolites production in vitro covering approximately more than a decade of research at one place in one review. Further, this extensive appraisal will be useful for the understanding and manipulation of secondary metabolites for enhanced production in vitro.

Chemical elicitors versus secondary metabolite production in vitro using plant cell, tissue and organ cultures: recent trends and a sky eye view appraisal

The effects of yeast extract and selected polysaccharide elicitors on secondary metabolite production, particularly of anthocyanin and phenolic acid, in cell suspension cultures of Vitis vinifera were investigated. All elicitors either maintained or promoted cell growth in culture. Overall, secondary metabolite production in V. vinifera cell suspension cultures responded differently to different elicitors. Chitosan, pectin, and alginate enhanced production of anthocyanin within 13 days of culture with levels of 2.5-, 2.5-, and 2.6-fold increase, respectively, over that of control. Chitosan, alginate, and gum arabic significantly promoted accumulation of phenolic acids, particularly 3-O-glucosyl-resveratrol, in V. vinifera cultures, as well as in the culture medium. Intracellular phenolic acid production was significantly enhanced by alginate and chitosan, with 1.7- and 1.5-fold levels, respectively, of that of control. Extracellular phenolic acid production was also significantly increased in the presence of chitosan and gum arabic, with levels of 3.3- and 1.7-fold higher, respectively, than those of control. In addition, DPPH (1,1-diphenyl-2-picrylhydrazyl) radical scavenging activity was enhanced in the presence of elicitors, and this was positively correlated with increased accumulation of anthocyanin in V. vinifera cell suspension cultures.

Polysaccharide elicitors enhance anthocyanin and phenolic acid accumulation in cell suspension cultures of Vitis vinifera

This study was undertaken to investigate the effects of salicylic acid (SA) and methyl jasmonate (MeJA) on anthocyanin induction, biomass accumulation, and color value (CV) indices for both pigment content (PC) and pigment production (PP) in callus cultures of Rosa hybrida cv. Pusa Ajay. A concentration-dependent response was exhibited by cultures on SA and MeJA at different concentrations individually or in combinations to Euphorbia millii medium supplemented with 204.5 mM sucrose, 2.45 μM indole butyric acid and 2.33 μM kinetin. There was positive influence on both callus biomass and anthocyanin accumulation. Treatment with 0.5 μM MeJA was most effective in inducing anthocyanin biosynthesis in callus cultures. Anthocyanin accumulation in callus cultures was enhanced with the addition of SA and MeJA, but these did not differ significantly from control for the number of days required for pigment initiation and for color intensification. Moreover, the addition of 0.5 μM MeJA alone resulted in a higher frequency of color response (97.25 %), PC (3.48 ± 0.07 CV g−1 FW), and PP (1.56 ± 0.03 CV test tube−1) over control. In contrast, the presence of higher levels of SA (400 μM) and MeJA (5.0 μM) reduced frequency of color response, as well as levels of PC and PP. MeJA did not increase biomass accumulation but promoted frequency of color response, PC and PP. Hence, it was suggested that 0.5 μM MeJA promoted anthocyanin production in rose callus cultures. Significant correlation was found between frequency of response and each of the PC (r = 0.988) and PP (r = 0.990). Furthermore, PC and PP were also highly correlated (r = 0.998).

Influence of salicylic acid and methyl jasmonate elicitation on anthocyanin production in callus cultures of Rosa hybrida L.

Gymnema sylvestre is a natural source of gymnemic acids—a group of closely related triterpenoid saponins used in the treatment of diabetes. The present study is aimed at enhancing gymnemic acid production in G. sylvestre cell suspension cultures using the signaling molecules—methyl jasmonate and salicylic acid. Methyl jasmonate yielded the maximum gymnemic acid content of 135.41 ± 0.43 mg g−1 dry cell weight (DCW), 72 h after elicitor application. Salicylic acid, on the other hand, evoked a moderate response reaching a maximum of 43.27 ± 0.80 mg g−1 DCW, 48 h after application. The results of the present study increase the possibility for commercial production of gymnemic acids on a large scale using G. sylvestre cell suspensions.

https://link.springer.com/content/pdf/10.1007%2Fs11627-014-9655-8.pdf

Gymnemic acid enhancement in the suspension cultures of Gymnema sylvestre by using the signaling molecules—methyl jasmonate and salicylic acid

Effects of chitosan and salicylic acid on the production of pharmacologically attractive secondary metabolites in callus cultures of Fagonia indica.

The influence of varied concentrations of sucrose and ammonical (NH4+) nitrogen on in vitro induction and expression of anthocyanin pigments from Rosa hybrida cv. ‘Pusa Ajay’ was investigated. Of two explants (petal and leaf discs) selected and cultured under two different conditions (light and dark), leaf discs were found to be most suitable for callus initiation. Profuse and early callus induction was observed when leaf discs of rose were cultured under total dark conditions on solid Murashige and Skoog (MS) medium supplemented with 4.0 mg l−1 2,4-dichlorophenoxyacetic acid (2,4-D). Early pigment initiation, enhancement and maximum anthocyanin production from calluses were recorded when leaf discs were cultured on Euphorbia millii (EM) medium supplemented with 7% sucrose compared with calluses cultured at 4% sucrose concentration under 16/8 h (light/dark) photoperiod regime. Reducing the concentration of NH4+ nitrogen in the solid MS medium led to slight improvement in anthocyanin production in rose leaf calluses.

Induction of anthocyanin pigments in callus cultures of Rosa hybrida L. in response to sucrose and ammonical nitrogen levels

Lesser Florican Sypheotides indicus , a Critically Endangered bustard species, now breeds in only a few restricted and fragmented ranges, comprising a mosaic of grasslands and croplands, in northwest and peninsular India. The global population estimates range between 300-600 males. The migration patterns and habitat utilisation across non-breeding habitats are poorly known, and in this study, we aimed to estimate the home ranges, migratory patterns, and non-breeding habitat of a male (RSD-1) and female (RSD-2) Lesser Florican in Blackbuck National Park (BNP), Gujarat, which were fitted with solar-powered Platform Transmitter Terminal (PTT). The breeding and non-breeding home ranges were determined by the minimum convex polygon (MCP) and fixed kernel methods. The breeding home range of the male (RSD-1) varied from 16.39 sq. km (95% MCP) in 2020 to 0.23 sq. km (95% MCP) in 2021, and 16.13 sq. km (95% MCP) in non-breeding season. For the female (RSD-2), the breeding home range size was 5.40 sq. km (95% MCP home-range), and it varied from about 7 sq. km to 1.57 sq. km in the non-breeding season. This study provides new insights into home range and dispersal behaviour in Lesser Florican across the mosaic of its fragmented habitats, and we recommend long-term telemetry studies to be taken up across non-breeding habitats. 

Breeding and Non-Breeding Home Range, and Dispersal Patterns of The Critically Endangered Lesser Florican Sypheotides indicus (Miller, 1782)

To establish a resourceful tissue culture system to induce anthocyanin pigments, research was conducted to obtain high quality callus from leaf explant of Rosa hybrida cv. Pusa Ajay. Of the different treatments employed for callus induction using Murashige and Skoog (MS) medium, a treatment combination of 19.60 μM indole3-butyric acid (IBA) + 4.65 μM kinetin (Kin) + 108.6 mM adenine sulphate (AdS) gave the maximum induction coefficient (97.75 ± 1.11%) along with maximum gain in callus biomass accumulation. This treatment also resulted in the lowest fresh-and dry-cell weight ratio (26.52) suggesting actual gain in callus biomass accumulation. Correlation analysis indicated a significant positive correlation between callus induction coefficient and cell fresh-(r = 0.939) and dry-(r = 0.951) weight.

Callus induction and proliferation from Rosa hybrida leaf explants

Endangered Asiatic lions (Panthera leo persica) are renowned for their resilience and as a flagship of successful conservation and management. Lions dispersing out of the Gir forest have established themselves in the coastal habitats for about 25 years. We propose that the home range and spatial distribution of lions inhabiting the coastal habitats would be distinct from the forested habitats of the protected area. Each individual was monitored for an average of 367.2 ± 99.05 days from 2019 to 2021. The mean core area was 33.8 km2 (50% FK, SE 8.7 km2) and the overall average range was 171.8 km2 (90% FK, SE 40.5 km2). The home ranges were significantly larger for lions residing in the coastal area compared to lions in the protected area. The lion distribution model was built on MaxEnt, and inputs included location fixes of lions and variables, including 18 land use categories and Euclidean distance to linear infrastructures and human settlements. Lions were shown to use forest habitat patches extensively, followed by available habitats around water sources and wasteland. The study highlights the importance of corridors connecting to the Gir protected area and the importance of coastal forest patches for lion conservation and management. 

/pdf/living-on-the-sea-coast-ranging-and-habitat-distribution-of-1fntd4h6.pdf

Mohan Ram

Papers

Influence of salicylic acid and methyl jasmonate elicitation on anthocyanin production in callus cultures of Rosa hybrida L.

Induction of anthocyanin pigments in callus cultures of Rosa hybrida L. in response to sucrose and ammonical nitrogen levels

Breeding and Non-Breeding Home Range, and Dispersal Patterns of The Critically Endangered Lesser Florican Sypheotides indicus (Miller, 1782)

Callus induction and proliferation from Rosa hybrida leaf explants

Living on the sea-coast: ranging and habitat distribution of Asiatic lions