Two mycoheterotrophic orchids from Thailand tropical dipterocarpacean forests associate with a broad diversity of ectomycorrhizal fungi

<p>Abstract</p> <p>Background</p> <p>Mycoheterotrophic plants are considered to associate very specifically with fungi. Mycoheterotrophic orchids are mostly associated with ectomycorrhizal fungi in temperate regions, or with saprobes or parasites in tropical regions. Although most mycoheterotrophic orchids occur in the tropics, few studies have been devoted to them, and the main conclusions about their specificity have hitherto been drawn from their association with ectomycorrhizal fungi in temperate regions.</p> <p>Results</p> <p>We investigated three Asiatic Neottieae species from ectomycorrhizal forests in Thailand. We found that all were associated with ectomycorrhizal fungi, such as Thelephoraceae, Russulaceae and Sebacinales. Based on ¹³C enrichment of their biomass, they probably received their organic carbon from these fungi, as do mycoheterotrophic Neottieae from temperate regions. Moreover, ¹³C enrichment suggested that some nearby green orchids received part of their carbon from fungi too. Nevertheless, two of the three orchids presented a unique feature for mycoheterotrophic plants: they were not specifically associated with a narrow clade of fungi. Some orchid individuals were even associated with up to nine different fungi.</p> <p>Conclusion</p> <p>Our results demonstrate that some green and mycoheterotrophic orchids in tropical regions can receive carbon from ectomycorrhizal fungi, and thus from trees. Our results reveal the absence of specificity in two mycoheterotrophic orchid-fungus associations in tropical regions, in contrast to most previous studies of mycoheterotrophic plants, which have been mainly focused on temperate orchids.</p

Transfer of chlorsulfuron resistance from tobacco to birdsfoot trefoil (Lotus corniculatus) by asymmetric somatic hybridization

A method was developed for rapid plant regeneration from protoplasts of birdsfoot trefoil (Lotus corniculatus cv. Leo) using in vitro cotyledons and a new enzyme formula. Protoplasts of a transgenic Nicotiana tabacum cv. Xanthi line KCR were isolated from leaves, in vitro shoots, and calli by an enzyme formula consisting of 0.5 % Cellulase R-10 and 0.05 % Pectolyase Y23 with either 0.4 M sucrose or 0.5 M mannitol as the osmoticum. Nine asymmetric fusion experiments were conducted between iodoacetate inactivated birdsfoot trefoil and irradiated transgenic tobacco protoplasts. The fusion products underwent several divisions but no visible colonies were obtained. Resistance analyses revealed the inactivation of the herbicide resistant gene in the transgenic tobacco calli. A putative chlorsulfuron resistant line has been obtained by in vitro selection from birdsfoot trefoil cotyledonous protoplasts. Their regenerants had normal ploidy, and expressed improved tolerance when sprayed with chlorsulfuron at the rate of 30 g/ha