AgNO3: a potential regulator of ethylene activity and plant growth modulator

The aim of this review is to critically analyze the role of silver nitrate (AgNO3) in modulating plant growth and development. In recent years, basic studies on ethylene regulation opened new vistas for applied research in the area of micro-propagation, somatic embryogenesis, in vitro flowering, growth promotion, fruit ripening, and sex expression. Silver nitrate has proved to be a very potent inhibitor of ethylene action and is widely used in plant tissue culture. Few properties of silver nitrate such as easy availability, solubility in water, specificity and stability make it very useful for various applications in exploiting plant growth regulation and morphogenesis in vivo and in vitro. Silver ion mediated responses seem to be involved in polyamines, ethylene- and calcium- mediated pathways, and play a crucial role in regulating physiological process including morphogenesis. The molecular basis for regulation of morphogenesis under the influence of silver nitrate is completely lacking. This review compiles published reports of silver nitrate-mediated in vitro and in vivo studies and focuses on fundamental and applied aspects of plant growth modulation under the influence of silver nitrate.

Induction of in vitro flowering in Capsicum frutescens under the influence of silver nitrate and cobalt chloride and pollen transformation

The influence of silver nitrate (AgNO3) and cobalt chloride (CoCl2) on shoot multiplication and in vitro flowering in Capsicum frutescens Mill. was investigated. Exogenous administration of AgNO3 and CoCl2 at a concentration of 30 micronM resulted in the maximum tissue response in terms of shoot length and number of shoots after 45 days culturing on MS medium. Both silver nitrate (40 micronM) and cobalt chloride (30 micronM) influenced in vitro flowering after 25 and 45 days respectively. This is the first report on in vitro flowering in C. frutescens. The study also demonstrated successful transformation of pollen obtained from the in vitro flowers. Since capsicum is highly recalcitrant to in vitro plant regeneration, the results of the study may be highly useful in transformation of capsicum using germ free in vitro flowers.

Isolation and characterization of hydrocarbon producing green alga Botryococcus braunii from Indian freshwater bodies

Samples of green colonial unicellular microalga Botryococcus braunii were collected from Bear Shola Falls at Kodaikanal (latitude 10.31 N and longitude 77.32 E), Tamil Nadu, India. Specimens were isolated, cultured and examined for its hydrocarbon content, morphological features and DNA structural resemblance with the known strain to confirm its identity. Inter simple sequence repeats (ISSR) finger printing revealed strong genetic similarity among the authentic strain (B. braunii N-836) and the Indian isolated strain (B. braunii CFTRI- Bb1) from Kodaikanal. The type of hydrocarbons produced by the Kodaikanal isolates were analyzed and identified as saturated hydrocarbons in the range of C21 to C33 by GCMS. Tetracosane and octacosane were found as the major components among the saturated hydrocarbons produced by this alga, constituting 17.6 percent and 14.8 percent respectively. Hydrocarbon content of the organism was in the range of 13-18 percent of its dry biomass. The fat content of the organism was found to be 22 percent (w/w). Palmitic and oleic acids were found to be major fatty acids produced by the alga. Lutein and beta-carotene were found to be the major carotenoids and constituted about 64.1 percent and 25.1 percent respectively of the total carotenoids. Based on ISSR finger printing and hydrocarbon analyses the new algal strain from Kodaikanal was identified as Botryococcus braunii.