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

Enhancement of the efficacy of the parasitoid, Microctonus hyperodae Loan (Hymenoptera: Braconidae) by provision of floral resources to improve biological control of its host, the Argentine stem weevil (Listronotus bonariensis) (Kuschel) (Coleoptera: Curculionidae)

In this study, conservation biological control principles were applied to increase the efficacy of Microctonus hyperodae Loan (Hymenoptera: Braconidae), a parasitoid of the Argentine stem weevil (Listronotus bonariensis (Kuschel) (Coleoptera: Curculionidae)). The Argentine stem weevil is a serious pest in New Zealand pasture. Seven flowering plant species were selected for laboratory experiments to assess the best plant species to increase the longevity of M hyperodae. Longevity of the parasitoid was significantly increased with buckwheat (Fagopyrum esculentum Moench) compared with six other flowering plants. Floral architecture measurements and nectar quality analysis were used to understand the floral selectivity and consequent 'preferences' of the parasitoids. A wider corolla aperture and a shorter corolla depth, as well as the sucrose/(glucose+fructose) ratio of the nectar were positively correlated with the longevity of M hyperodae. These results were compared with those for other parasitoids. Lifetime carbohydrate reserves were analysed in continuously-fed and unfed (water control) M. hyperodae in the laboratory. Total sugar levels (as a measure of nutritional state) decreased continuously throughout unfed parasitoids' lifespans, whereas in continuously-fed individuals, levels increased initially and then decreased. Glucose dominated in the unfed parasitoids while glucose and fructose dominated in the fed individuals. The common insect haemolymph sugar, trehalose, was not detected in unfed M. hyperodae, but was detected in fed parasitoids. Parasitoids that fed from buckwheat in the laboratory showed higher sucrose levels immediately after feeding, but these declined to the levels observed in honey-fed individuals after one hour. The fructose/total sugars (f/t) ratio was clearly different between the fed and unfed M. hyperodae. This ratio was a good indicator for distinguishing fed from unfed parasitoids and was therefore a useful tool for understanding the feeding history of M. hyperodae. Buckwheat was deployed in the field to assess parasitoid abundance at different distances from the floral resources. The highest number of M. hyperodae occurred near buckwheat plots. The number rapidly declined with increasing distance and was at its lowest at 7 to 8m, followed by increasing numbers. Parasitoid numbers significantly increased near buckwheat plots compared with the middle and furthest distances. Field-collected parasitoids were analysed to determine their nutritional state and feeding history. A high proportion (79%) of parasitoids collected near buckwheat plots had fed and, therefore, had an increased total sugar level and fit ratio. Only 20% collected from grasses on road-side verges apparently had access to sugar sources. The fit ratio in combination with total sugar levels was a useful tool to understand the nutritional state and feeding history of field-collected parasitoids. The effect of buckwheat deployment in the field on parasitism rates of L. bonariensis was measured. Parasitism rates of the first summer generation of L. bonariensis near buckwheat plots were increased by 250% compared with the controls. Parasitism rates of the second summer generation of L. bonariensis did not differ between those near buckwheat and the controls

Economics of supply reliability of irrigation water

In this study, we have assessed the economic impact of potential increase in supply reliability of irrigation water in the Hinds Plains Area in the Ashburton district. The Hinds catchment has a number of irrigation schemes namely, Rangitata Diversion Race (provides water for Mayfield Hinds and Valetta Schemes), Barrhill Chertsey, Eiffelton and Lynford Schemes. All these schemes have varying supply reliability which ranges from 40% to 80% approximately. First, we estimated the relationship between water availability and pasture growth using experimental data. We then employed this relationship to estimate the potential incremental pasture growth with assumed increased supply reliability (95%) at farm level. We estimated the farm level benefit of increased pasture production in terms of saved costs in supplementary feed. These farm level estimates were used to assess the catchment level farm income gain. The catchment level income gain was then employed to assess the regional level economic gain (GDP and employment) by the socio-accounting matrix input-output model (SAMI-O) simulation. Income gain at catchment level is estimated to vary from $16 to$17million. This implies an additional gain in regional level income (GDP) of $85 to$91million and additional employment of 137 FTE to 207 FTE. The study indicates the importance of an increase in irrigation efficiency at farm level for the local and regional economy and also discusses the potential environmental impacts of increase irrigation efficiency at catchment level

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

Sri Lanka industrial estate siting study

Expansion and diversification of the existing industrial base in Sri Lanka are major components of the country’s economic development policy. Though increased industrialization holds the promise of an improved economy, it may accompany numerous environmental and social risks if executed in an improper manner. The siting ot industrial estates that are designed and operated with appropriate infrastructure and environmental controls is the best possible approach to minimize these risks