Novel Plant Regeneration and Transient Gene Expression in Catharanthus roseus

Catharanthus roseus genetic transformation represents a real challenge due, in part, to the lack of regeneration capability and this species’ recalcitrance to genetic transformation. In the present work, we demonstrate the regeneration of C. roseus plants from hypocotyls and cotyledons, using specific growth regulator conditions. Plants derived from hypocotyls and cotyledons were successfully acclimated and grown in the greenhouse. Furthermore, C. roseus meristem tissues were shown to have high shoot regeneration potential under conditions optimised for cotyledon- and hypocotyl-derived shooting. Meristem tissues were therefore investigated as a genetic transformation targets using both Agrobacterium tumefaciens and A. rhizogenes. Although meristem-derived shoots transformed with A. tumefaciens harbouring a p35S GUSplus construct revealed transient GUS expression and protein accumulation, they were not amenable to selection even after two months on selection medium. Transformation of C. roseus meristem tissues with A. rhizogenes resulted in a typical hairy root phenotype, in which the adventitious root tissue strongly expressed the p35S GUSplus construct, as revealed by intense GUS staining

Mity model: Tetranychus urticae, a candidate for chelicerate model organism

Correspondance: [email protected] audienceChelicerates (scorpions, horseshoe crabs, spiders, mites and ticks) are the second largest group of arthropods and are of immense importance for fundamental and applied science. They occupy a basal phylogenetic position within the phylum Arthropoda, and are of crucial significance for understanding the evolution of various arthropod lineages. Chelicerates are vectors of human diseases, such as ticks, and major agricultural pests, such as spider mites, thus this group is also of importance for both medicine and agriculture. The developmental genetics of chelicerates is poorly understood and a challenge for the future progress for many aspects of chelicerate biology is the development of a model organism for this group. Toward this end, we are developing a chelicerate genetic model: the two-spotted spider mite Tetranychus urticae. T. urticae has the smallest genome of any arthropod determined so far (75 Mbp, 60% of the size of the Drosophila genome), undergoes rapid development and is easy to maintain in the laboratory. These features make T. urticae a promising reference organism for the economically important, poorly studied and species-rich chelicerate lineag

The genome of Tetranychus urticae reveals herbivorous pest adaptations

The spider mite Tetranychus urticae is a cosmopolitan agricultural pest with an extensive host plant range and an extreme record of pesticide resistance. Here we present the completely sequenced and annotated spider mite genome, representing the first complete chelicerate genome. At 90 megabases T. urticae has the smallest sequenced arthropod genome. Compared with other arthropods, the spider mite genome shows unique changes in the hormonal environment and organization of the Hox complex, and also reveals evolutionary innovation of silk production. We find strong signatures of polyphagy and detoxification in gene families associated with feeding on different hosts and in new gene families acquired by lateral gene transfer. Deep transcriptome analysis of mites feeding on different plants shows how this pest responds to a changing host environment. The T. urticae genome thus offers new insights into arthropod evolution and plant–herbivore interactions, and provides unique opportunities for developing novel plant protection strategies