Developmental variation during seed germination and biochemical responses of Brassica rapa exposed to various colored lights.

Light acting as elicitor or stress inducer, it plays a pivotal role in all developmental processes of plant providing necessary building blocks for growth and primary and secondary metabolites production. The main objective of the current study was to investigate the individual effect of colored lights on developmental processes and production of polyphenolics contents in Brassica rapa. In this study, the red and white lights (control) were found to be the most effective sources for seed germination (91%) in Brassica rapa. Similarly, red light enhanced radicle growth (102 mm), while green light suppressed radicle growth (60 mm) as compared to control (67 mm). The red light also promoted the plumule growth (50 mm) as compared to control (37 mm). The maximum biomass gain (67 mg) was observed under red light as compared to control (55 mg). Currently, the maximum total phenolics content (9.49 mg/g-DW) and phenolics production (379.616 mg/L) was observed under the influence of blue lights as compared to control (0.23 mg/g-DW and 8.91 mg/L). Similarly, the blue lights also enhanced the biosynthesis of total flavonoids content (2.2611 mg/g-DW) and flavonoids production (90.44 mg/L) as compared to control (0.0318 md/g-DW and 0.8268 mg/L). The current results represents that red and blue lights are the most effective sources for plantlets development and production of polyphenolics content in Brassica rapa.

Selection of suitable propagation method for consistent plantlets production in Stevia rebaudiana (Bertoni).

Stevia rebaudiana (Bert.) is an emerging sugar alternative and anti-diabetic plant in Pakistan. That is why people did not know the exact time of propagation. The main objective of the present study was to establish feasible propagation methods for healthy biomass production. In the present study, seed germination, stem cuttings and micropropagation were investigated for higher productivity. Fresh seeds showed better germination (25.51-40%) but lost viability after a few days of storage. In order to improve the germination percentage, seeds were irradiated with 2.5, 5.0, 7.5 and 10 Gy gamma doses. But gamma irradiation did not show any significant change in seed germination. A great variation in survival of stem cutting was observed in each month of 2012. October and November were found the most suitable months for stem cutting survival (60%). In order to enhance survival, stem cuttings were also dipped in different plant growth regulators (PGRs) solution. Only indole butyric acid (IBA; 1000 ppm) treated cutting showed a higher survival (33%) than control (11.1%). Furthermore, simple and feasible indirect regeneration system was established from leaf explants. Best callus induction (84.6%) was observed on MS-medium augmented with 6-benzyladenine (BA) and 2,4-dichlorophenoxyacetic acid (2,4-D; 2.0 mg l(-1)). For the first time, we obtained the highest number of shoots (106) on a medium containing BA (1.5 mg l(-1)) and gibberellic acid (GA3; 0.5 mg l(-1)). Plantlets were successfully acclimatized in plastic pots. The current results preferred micropropagation (85%) over seed germination (25.51-40%) and stem cutting (60%).

Antioxidant activity via DPPH, gram-positive and gram-negative antimicrobial potential in edible mushrooms.

Edible mushrooms (EMs) are nutritionally rich source of proteins and essential amino acids. In the present study, the antioxidant activity via 1,1-diphenyl-2-picrylhydrazyl (DPPH) and antimicrobial potential in EMs (Pleurotus ostreatus, Morchella esculenta, P. ostreatus (Black), P. ostreatus (Yellow) and Pleurotus sajor-caju) were investigated. The DPPH radical scavenging activity revealed that the significantly higher activity (66.47%) was observed in Morchella esculenta at a maximum concentration. Similarly, the dose-dependent concentrations (200, 400, 600, 800 and 1000 µg) were also used for other four EMs. Pleurotus ostreatus exhibited 36.13% activity, P. ostreatus (Black (B)) exhibited 30.64%, P. ostreatus (Yellow (Y)) exhibited 40.75% and Pleurotus sajor-caju exhibited 47.39% activity at higher concentrations. Furthermore, the antimicrobial potential were investigated for its toxicity against gram-negative bacterial strains (Escherichia coli, Pseudomonas aeroginosa, Salmonella typhi, Klebsiella pneumonia, Erwinia carotovora and Agrobacterium tumifaciens), gram-positive bacterial strains (Bacillus subtilis, Bacillus atrophaeus and Staphylococcus aureus) and a fungal strain (Candida albicans) in comparison with standard antibiotics. Antimicrobial screening revealed that the ethanol extract of P. ostreatus was active against all microorganism tested except E. coli. Maximum zone of inhibition (13 mm) was observed against fungus and A. tumifaciens. P. sajor-caju showed best activities (12.5 mm) against B. subtilis, B. atrophaeus and K. pneumonia. P. ostreatus (Y) showed best activities against P. aeroginosa (21.83 mm), B. atrophaeus (20 mm) and C. albicans (21 mm). P. ostreatus (B) exhibited best activities against C. albicans (16 mm) and slightly lower activities against all other microbes except S. typhi. M. esculenta possess maximum activities in terms of inhibition zone against all microorganisms tested except S. typhi.

Efficient regeneration for enhanced steviol glycosides production in Stevia rebaudiana (Bertoni).

An efficient method of regeneration for antidiabetic plant (Stevia rebaudiana) has been established for healthy biomass and main steviol glycosides (SGs) production, using different PGRs and agar concentrations. Higher callus induction (93.3%) was recorded when leaf explants were placed on an MS medium supplemented with 3.5 gL(-1) agar and 2.0 mgL(-1) 2,4-D. The addition of 7.0 gL(-1) agar and BA (1.0, 2.0 and 4.0 mgL(-1)) significantly (P<0.01) influences shooting response (100%). A maximum mean shoot length (13.03 cm) and 28 shoots per explant were observed on a medium containing 1.0 mgL(-1) BA. However, the maximum number of leaves (132.67) was encouraged by the addition of BA (1.0 mgL(-1)) and Kin (1.0 mgL(-1)). Lower agar (3.5 gL(-1)), IAA (2.0 mgL(-1)), and NAA (2.0 mgL(-1)) concentrations significantly influence the rooting percent (100%), the mean root length (2.9 cm), and the number of roots per plantlet (26.3). These plantlets were successfully acclimatized in the soil. The BA (3.0 mgL(-1)) in combination with Kin (3.0 mgL(-1)) and 3.5 gL(-1) agar increases dulcoside-A content (Dul-A; 71.8 µg/g-DW) in shoots compared to control (50.81 µg/g-DW). Similar PGRs with 7.0 gL(-1) significantly increases the production of steviosides (Stev. 82.48 µg/g-DW). A higher rebaudioside-A content (Reb-A; 12.35 µg/g-DW) was observed in shoots that underwent the addition of BA (1.0 mgL(-1)) and 7.0 gL(-1) agar than in control (07.39 µg/g-DW). Hereby, we developed an efficient and cost-effective method for regeneration and major SGs production, which could be helpful for future studies on this species.