De novo sequencing and characterization of floral transcriptome in two species of buckwheat (Fagopyrum)

<p>Abstract</p> <p>Background</p> <p>Transcriptome sequencing data has become an integral component of modern genetics, genomics and evolutionary biology. However, despite advances in the technologies of DNA sequencing, such data are lacking for many groups of living organisms, in particular, many plant taxa. We present here the results of transcriptome sequencing for two closely related plant species. These species, <it>Fagopyrum esculentum </it>and <it>F. tataricum</it>, belong to the order Caryophyllales - a large group of flowering plants with uncertain evolutionary relationships. <it>F. esculentum </it>(common buckwheat) is also an important food crop. Despite these practical and evolutionary considerations <it>Fagopyrum </it>species have not been the subject of large-scale sequencing projects.</p> <p>Results</p> <p>Normalized cDNA corresponding to genes expressed in flowers and inflorescences of <it>F. esculentum </it>and <it>F. tataricum </it>was sequenced using the 454 pyrosequencing technology. This resulted in 267 (for <it>F. esculentum</it>) and 229 (<it>F. tataricum</it>) thousands of reads with average length of 341-349 nucleotides. <it>De novo </it>assembly of the reads produced about 25 thousands of contigs for each species, with 7.5-8.2× coverage. Comparative analysis of two transcriptomes demonstrated their overall similarity but also revealed genes that are presumably differentially expressed. Among them are retrotransposon genes and genes involved in sugar biosynthesis and metabolism. Thirteen single-copy genes were used for phylogenetic analysis; the resulting trees are largely consistent with those inferred from multigenic plastid datasets. The sister relationships of the Caryophyllales and asterids now gained high support from nuclear gene sequences.</p> <p>Conclusions</p> <p>454 transcriptome sequencing and <it>de novo </it>assembly was performed for two congeneric flowering plant species, <it>F. esculentum </it>and <it>F. tataricum</it>. As a result, a large set of cDNA sequences that represent orthologs of known plant genes as well as potential new genes was generated.</p

The influence of flower morphology and nectar quality on the longevity of a parasitoid biological control agent.

Conservation biological control aims to enhance the efficacy of arthropod biological control agents, such as parasitoids, partly by providing them with access to floral nectar. However, the suitability of a flower species for providing nectar to a parasitoid is dependent on the morphologies of the parasitoid and the flower, as well as on the quality of the nectar. The effects of seven flower species on the longevity of Microctonus hyperodae (Hymenoptera Braconidae), a parasitoid of the Argentine stem weevil, Listronotus bonariensis (Coleoptera: Curculionidae), were measured in the laboratory. The flowers were phacelia (Phacelia tanacetifolia), buckwheat (Fagopyrum esculentum), alyssum (Lobularia maritima), coriander (Coriandrum sativum), white clover (Trifolium repens), red clover (Trifolium pratense) and white mustard (Sinapis alba). The results suggested M. hyperodae was unable to reach nectar of red clover, white clover, alyssum and phacelia, but was able to gain access to the nectar of the other three species. However, only buckwheat and coriander increased its longevity. Flower corolla aperture and depth probably determined the parasitoid’s access to nectar. Accessible nectars were analyzed for sugar composition and the effect of the sucrose/(glucose + fructose) ratio on nectar suitability was assessed. The relevance of these results to other hymenopteran parasitoid species is discussed in terms of selecting the most appropriate floral diversity in agricultural extensification programmes