Transgenic cotton resistant to herbicide bialaphos

Resistance to bialaphos, a non-selective herbicide, was intro duced into cotton through genetic engineering. A gene encoding phosphinothric in acetyltransferase (bar) from Streptomyces hygroscopicus was inserted into elite varieties of cotton through particle bombardment. Based on the marker gene, -glucuronidase (gus) expression, a total of 18 Pima (Gossypium barbadense), 45 DP50 (G. hirsutum L.), 20 Coker 312 (G. hirsutum) and 2 El Dorado (G. hirsutum) transgenic plants were recovered. Integration of the bar gene into cotton genomic DNA was confirmed by Southern blot analysis and gene expression was confirmed by northern blot and enzyme assays. Herbicide (Basta®) tolerance up to 15 000 ppm was demonstrated in greenhouse trials. The newly introduced herbicide tolerance trait is inherited in a Mendelian fashion in the progenies of germline transformants. This study demonstrates the potential for particle bombardment to introduce commerically important genes directly into elite varieties of cotton. This mode of gene transfer can expedite the introduction of transgenic cotton products into world markets     

Survival of an introduced ectomycorrhizal Laccaria bicolor strain in a European forest plantation monitored by mitochondrial ribosomal DNA analysis

Mitochondrial and nuclear genes have different inheritance, thus studies of fungal populations should use both mitochondrial and nuclear markers. Using nuclear markers, the S238N strain of the ectomycorrhizal basidiomycete Laccaria bicolor ((Maire) Orton) has been previously shown to persist for at least 10 yr after outplanting in a plantation of Douglas fir ( Pseudotsuga menziesii (Mir.) Franco) inoculated with this strain. In the present study, we have sampled 539 sporophores of Laccaria spp. from this plantation, some of which had the S238N nuclear genotype, to study mitochondrial DNA polymorphism and persistence of the inoculated S238N mitochondrial genome. Length polymorphism in fragments of the large subunit of mitochondrial ribosomal DNA (LrDNA) allowed distinction of the haplotypes present in the plantation at the species level. In addition, heteroduplex analysis and sequencing revealed intraspecific polymorphism of LrDNA among the L. bicolor sporophores and enabled specific identification of S238N LrDNA. This haplotype was only retained in sporophores carrying the S238N nuclear genome, confirming the survival of this introduced strain in a natural population.     

Three New “Biological” Species of Tetrahymena (T. hegewischi n. sp., T. sonneborni n. sp., T. nipissingi n. sp.) and Temperature Tolerance of Members of the “pyriformis” Complex1

Stocks of the Tetrahymena pyriformis complex have been collected in North America and their mating reactivity has been studied. In addition to stocks mating with Tetrahymena americanis, T. borealis, T. pigmentosa, T. hyperangularis, and T. australis, stocks belonging to old syngen 5 and three new mating groups, numbers 13, 14, and 15, were discovered. Syngen 5 and groups 13 and 14 are distinct “biological” species, based on their reproductive isolation from other groups and on the ability of withingroup crosses to produce immature progeny. These species have been named T. hegewischi n. sp., T. sonneborni n. sp., and T. nipissingi n. sp., respectively. The cross between the two group 15 stocks did not produce immature progeny, and there is not sufficient evidence to conclude that this pair of stocks represents a separate species. Temperature tolerance measurements have been made on stocks representing all known micronucleate members of “pyriformis” complex. Within each species, the range of temperature tolerances is narrow; the average within-species standard deviation is 0.63°C. The species averages range from 32.7 to 40.7°C. Using syngen numbers, the order from lowest to highest temperature tolerance is 9, 8, 10, 7, 6, 4, 13, 14, 12, 11, 5, 3, 2, 1. The large differences among species make temperature tolerance a useful aid in identification, but the origins of the differences among species are unknown.