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

Abstract

Key messageSeven 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.AbstractTo 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.Electronic supplementary materialThe online version of this article (doi:10.1007/s00122-015-2455-7) contains supplementary material, which is available to authorized users.

Identification and evaluation of intervarietal substitution lines of rapeseed (Brassica napus L.) with donor segments affecting the diploidization rate of isolated microspores

“…It has actually been shown that homoeologous exchanges occur with higher frequency in resynthesized rapeseed genotypes or in crosses between such genotypes and natural rapeseed than in natural rapeseed itself Song et al 1995;Udall et al 2005;Szadkowski et al 2010;Chalhoub et al 2014). Furthermore Ecke et al (2015) found some evidence that such occurrences have happened during the development of the ISLs or already in the donor parent 'RS239'. About 40 % of the markers (186 out of 470 markers) on the diploid MDE map showed skewed segregations in the diploid MDE population.…”

“…In addition, a population of 323 doubled haploid ISLs, derived from microspores of BC 4 plants of the same cross with 'Express 617' as recurrent parent, was available to verify effects of specific genomic regions on the diploidization rate of microspores. The genetic characterization of the ISL population with 484 AFLP markers from a map constructed in a corresponding F 1 DH population (DH map) has been summarized in Ecke et al (2015); full details can be found in Nurhasanah (2010). Shortly, the ISLs carry an average of three donor segments, with a minimum of one and a maximum of nine.…”

“…In total, the minimum and maximum donor segment coverage on the DH map is 951 cM and 1587 cM, respectively, out of 2003 cM. Furthermore, information on marker segregations in a haploid MDE and a BC 1 population with 191 and 185 genotypes, respectively, derived from the same F 1 plant as the diploid MDE population (Ecke et al 2015) and the corresponding genetic maps (haploid MDE and BC 1 map) was available for comparison with the diploid MDE population.…”

“…The script automates the mapping process and distributes time critical processes to multiple copies of MAPMAKER in order to speed up the analysis. The mapping approach that was followed, which results in a high fidelity (HF) map of a subset of well ordered markers and a full map with all markers, was described in detail by Ecke et al (2015).…”

“…While there has been a small number of studies on the genetics of the embryogenic potential of isolated microspores in rapeseed and B. rapa, either by comparing skewed segregations in F 1 derived populations of non-colchicinized MDEs and F 2 or BC 1 populations (Foisset et al 1993;Ecke et al 2015) or by determining the embryogenic potentials of microspores from all individuals of an F 2 mapping population (Zhang et al 2003), to our knowledge there have been no studies until now about the genetic control of the diploidization rates of isolated microspores.…”