Production of cucumber fruits from the culture of ‘Marketmore-76’ plantlets
A procedure to produce fruits from cultured shoot tips of Cucumis sativus L. cultivar ‘Marketmore-76’ in vitro is described. Four-week-old shoot tips, derived from sterile germinated seedlings on a MS medium, were cultured in a 3.8-1 Mason jar using an automated plant culture system. Tips readily generated roots, leaves and flowers after another 4 to 8 weeks in culture. Administration of compressed air at a 300 ml/min flow rate for 30 min 10 or 15 times a day induced the development of parthenocarpic fruits from flowers. Fruits, up to 170 mm long by 35 mm diameter, were obtained within 30 to 45 d after flower opening.
Regeneration and Flowering in Vitro of `Burpless Hybrid' Cucumber Cultured from Excised Seed
Seeds of cucumber were separated from their seedcoats and excised into pieces comprising an embryonic axis and two cotyledons. The seed pieces were disinfested and explanted on modified Murashige and Skoog medium with 16 combinations of BAP and NAA. On all media, embryonic axes germinated and grew into whole plants within 4 weeks, but did not flower. Cotyledons developed adventitious shoots and male flowers on most media. The best shoot regeneration and the most female flowers were observed on medium with 2.0 mg BAP and 0.3 mg NAA/liter
Preservation in microbial mats: mineralization by a talc-like phase of a fish embedded in a microbial sarcophagus
Microbial mats have been repeatedly suggested to promote early fossilization of macroorganisms. Yet, experimental simulations of this process remain scarce. Here, we report results of 5 year-long experiments performed onfish carcasses to document the influence of microbial mats on mineral precipitation during early fossilization. Carcasses were initially placed on top of microbial mats. After two weeks, fishes became coated by the mats forming a compact sarcophagus, which modified the microenvironment close to the corpses. Our results showed that these conditions favoured the precipitation of a poorly crystalline silicate phase rich in magnesium. This talc-like mineral phase has been detected in three different locations within the carcasses placed in microbial mats for more than 4 years: 1) within inner tissues, colonized by several bacillary cells; 2) at the surface of bones of the upper face of the corpse buried in the mat; and 3) at the surface of several bones such as the dorsal fin which appeared to be gradually replaced by the Mg-silicate phase. This mineral phase has been previously shown to promote bacteria fossilization. Here we provide first experimental evidence that such Mg-rich phase can also be involved in exceptional preservation of animals.