Transposable elements generate population-specific insertional patterns and allelic variation in genes of wild emmer wheat (Triticum turgidum ssp. dicoccoides).

Background: Natural populations of the tetraploid wild emmer wheat (genome AABB) were previously shown to demonstrate eco-geographically structured genetic and epigenetic diversity. Transposable elements (TEs) might make up a significant part of the genetic and epigenetic variation between individuals and populations because they comprise over 80% of the wild emmer wheat genome. In this study, we performed detailed analyses to assess the dynamics of transposable elements in 50 accessions of wild emmer wheat collected from 5 geographically isolated sites.

Structure and extent of DNA methylation-based epigenetic variation in wild emmer wheat (T. turgidum ssp. dicoccoides) populations.

Background: The genetic structure and differentiation of wild emmer wheat suggests that genetic diversity is eco-geographically structured. However, very little is known about the structure and extent of the heritable epigenetic variation and its influence on local adaptation in natural populations.

Results: The structure and extent of the heritable methylation-based epigenetic variation were assessed within and among natural populations of Triticum turgidum ssp.

The basis for rootstock resilient to Capnodis species: screening for genes encoding δ-endotoxins from Bacillus thuringiensis.

Background: Conventional methods often fail to control the flatheaded borers Capnodis spp., major pests of stone fruit trees; the larvae are protected from insecticides and predation because they feed deep in the roots. A potential solution is transgenic trees producing in their roots toxic compounds such as Cry proteins of Bacillus thuringiensis (Bt).

Genetic and epigenetic dynamics of a retrotransposon after allopolyploidization of wheat.

Allopolyploidy, or the combination of two or more distinct genomes in one nucleus, is usually accompanied by radical genomic changes involving transposable elements (TEs). The dynamics of TEs after an allopolyploidization event are poorly understood. In this study, we analyzed the methylation state and genetic rearrangements of a high copied, newly amplified terminal-repeat retrotransposon in miniature (TRIM) family in wheat termed Veju.

Developmental timing of DNA elimination following allopolyploidization in wheat.

The elimination of DNA sequences following allopolyploidization is a well-known phenomenon. Yet, nothing is known about the biological significance, the mechanism, or the precise developmental timing of this event. In this study, we have observed reproducible elimination of an Aegilops tauschii allele in the genome of the second generation (S2) of a newly synthesized allohexaploid derived from a cross between Triticum turgidum and Ae.

Mating behaviour, life history and adaptation to insecticides determine species exclusion between whiteflies.

1. Negative interspecific interactions, such as resource competition or reproductive interference, can lead to the displacement of species (species exclusion). 2.

Variations in the mosquito larvicidal activities of toxins from Bacillus thuringiensis ssp. israelensis.

Comparing activities of purified toxins from Bacillus thuringiensis ssp. israelensis against larvae of seven mosquito species (vectors of tropical diseases) that belong to three genera, gleaned from the literature, disclosed highly significant variations in the levels of LC(50) as well as in the hierarchy of susceptibilities. Similar toxicity comparisons were performed between nine transgenic Gram-negative species, four of which are cyanobacterial, expressing various combinations of cry genes, cyt1Aa and p20, against larvae of four mosquito species as potential agents for biological control.

Large-scale survey of cytosine methylation of retrotransposons and the impact of readout transcription from long terminal repeats on expression of adjacent rice genes.

Transposable elements (TEs) represent approximately 45% of the human genome and 50-90% of some grass genomes. While most elements contain inactivating mutations, others are reversibly inactivated (silenced) by epigenetic mechanisms, including cytosine methylation. Previous studies have shown that retrotransposons can influence the expression of adjacent host genes.

Larvicidal activities against agricultural pests of transgenic Escherichia coli expressing combinations of four genes from Bacillus thuringiensis.

The genes cry1Ac and cry1Ca from Bacillus thuringiensis subsps. kurstaki HD-73 and aizawai 4J4, respectively, encoding delta-endotoxins against lepidopteran larvae were isolated, cloned and expressed in Escherichia coli, with and without cyt1Aa (encoding cytolytic protein) and p20 (accessory protein) from subsp. israelensis.

Cross-resistance spectra of Culex quinquefasciatus resistant to mosquitocidal toxins of Bacillus thuringiensis towards recombinant Escherichia coli expressing genes from B. thuringiensis ssp. israelensis.

Sixteen Escherichia coli clones were assayed against susceptible and Bacillus thuringiensis-resistant Culex quinquefasciatus larvae. The clones expressed different combinations of four genes from Bacillus thuringiensis ssp. israelensis; three genes encoded mosquitocidal toxins (Cry11Aa, Cry4Aa and Cyt1Aa) and the fourth encoded an accessory protein (P20).

Biotypes B and Q of Bemisia tabaci and their relevance to neonicotinoid and pyriproxyfen resistance.

Resistance monitoring for Bemisia tabaci field populations to the juvenile hormone mimic, pyriproxyfen, was conducted from 1996 to 2003 in commercial cotton fields in two areas of Israel: the Ayalon Valley (central Israel) and the Carmel Coast (northwestern Israel). Although the use of pyriproxyfen ceased in these areas in 1996-1997 (because of the resistance), resistance levels to pyriproxyfen declined to some extent in the fields but remained quite stable, and the susceptibility has not been totally restored. Two strains of B.

Mosquito larvicidal activity of transgenic Anabaena PCC 7120 expressing toxin genes from Bacillus thuringiensis subsp. israelensis.

Genes encoding the mosquito larvicidal toxins Cry4Aa, Cry11Aa, Cyt1Aa and the regulatory P20 from Bacillus thuringiensis subsp. israelensis were introduced into the nitrogen-fixing, filamentous cyanobacterium Anabaena PCC 7120 for expression under control of two strong promoters P(psbA) and P(A1). The clone pRVE4-ADRC displayed toxicity against fourth-instar larvae of Aedes aegypti, the highest ever achieved in cyanobacteria.