De novo transcriptome assemblies of five major European oilseed rape insect pests.

OBJECTIVE: Insect pests can cause severe losses in oilseed rape yields across Europe. Genomic and transcriptomic information is very limited for these insects. The aim of our study was to provide transcriptomic resources on several oilseed rape herbivores that will support research into their biology and help develop new methods of sustainable pest management. DATA: Transcriptomes for larval stages of five major European pest species were de novo assembled by Trinity assembler. Total number of transcripts ranged from 112,247 for Ceutorhynchus pallidactylus to 225,110 for Ceutorhyncus napi. Intermediate numbers of 140,588, 140,998 and 144,504, were found for Psylliodes chrysocephala, Dasineura brassicae, and Brassicogethes aeneus, respectively. Bench-marking universal single-copy orthologues analyses for each dataset indicated high degree of completeness for all five species. The transcriptomes extend the list of genomic data on insect larvae that constitute major pests of oilseed rape. The data provide information on larval physiology and form a basis to develop highly specific RNA interference-based plant protection.

Identification and genetic characterization by high-throughput SNP analysis of intervarietal substitution lines of rapeseed (Brassica napus L.) with enhanced embryogenic potential.

KEY MESSAGE: Seven intervarietal substitution lines were identified with embryogenic potentials up to 40.4 times that of the recurrent parent, providing an ideal material for further in depth studies of this trait. To identify genomic regions that carry genetic factors controlling embryogenic potential of isolated microspores of rapeseed, marker segregations were analysed in a segregating population of haploid microspore-derived embryos and a BC1 population from a cross between 'Express 617' and 'RS239'. After map construction 15 intervarietal substitution lines from the same cross with 'Express 617' as recurrent parent were selected with donor segments covering five genomic regions that had shown skewed segregations in the population of microspore-derived embryos but not in the BC1 population. By comparing the embryogenic potential of microspores of the 15 substitution lines and 'Express 617', seven lines were identified with significantly enhanced embryogenic potential ranging from 4.1 to 40.4 times that of 'Express 617'. To improve the genetic characterization of the selected lines, they were subjected to a high-throughput SNP analysis using the Illumina Infinium 60K chip for rapeseed. Based on 7,960 mapped SNP markers, one to eight donor segments per line, which cover 0.64-6.79% of the 2,126.1 cM of the SNP map, were found. The SNP analysis also gave evidence that homoeologous exchanges had occurred during the development of the substitution line population, increasing the genetic diversity within this population. By comparing donor segments between lines with significantly enhanced embryogenic potential and non-significant lines, 12 genomic regions were identified that may contain genetic factors controlling embryogenic potential in rapeseed. These regions range in size from 0 (represented by just one marker) to 26.8 cM and cover together just 5.42% of the SNP map.