Phenotypic, cytogenetic, and molecular marker analysis of Brassica napus introgressants derived from an intergeneric hybridization with Orychophragmus

Abstract

Aneuploids of a single species that have lost or gained different chromosomes are useful for genomic analysis. The polyploid nature of many crops including oilseed rape (Brassica napus) allows these plants to tolerate the loss of individual chromosomes from homologous pairs, thus facilitating the development of aneuploid lines. Here, we selected 39 lines from advanced generations of an intergeneric hybridization between Brassica rapa and Orychophragmus violaceus with accidental pollination by B. napus. The lines showed a wide spectrum of phenotypic variations, with some traits specific to O. violaceus. Most lines had the same chromosome number (2n = 38) as B. napus. However, we also identified B. napus nulli-tetrasomics with 22 A-genome and 16 C-genome chromosomes and lines with the typical B. napus complement of 20 A-genome and 18 C-genome chromosomes, as revealed by FISH analysis using a C-genome specific probe. Other lines had 2n = 37 or 39 chromosomes, with variable numbers of A- or C-genome chromosomes. The formation of quadrivalents by four A-genome chromosomes with similar shapes suggests that they were derived from the same chromosome. The frequent homoeologous pairing between chromosomes of the A and C genomes points to their non-diploidized meiotic behavior. Sequence-related amplified polymorphism (SRAP) analysis revealed substantial genomic changes of the lines compared to B. rapa associated with O. violaceus specific DNA bands, but only a few genes were identified in these bands by DNA sequencing. These novel B. napus aneuploids and introgressants represent unique tools for studies of Brassica genetics and for Brassica breeding projects.

Alternatively Spliced BnaPAP2.A7 Isoforms Play Opposing Roles in Anthocyanin Biosynthesis of Brassica napus L.

“…A B. napus alien introgression line was generated from the sequential crosses of ( B. rapa ssp. chinensis L. × Orychophragmus violaceus ) × B. napus by successive phenotypic selection and cytological observation ( Li and Heneen, 1999 ; Xu et al., 2019 ). After selfing for more than 10 generations, this line possessed the same chromosome complement (2n=38) as B. napus , a normal meiotic behavior, and a good seed-set.…”

Recruiting Distant Hybridization for Reshaping Meiotic Recombination

“…Although, the frequency and patterning of recombination is under tight control, AABC, BBAC and CCAB allotriploid Brassicas are capable of overcoming this barrier by inducing higher ratio and wider distribution of recombination across the chromosomes or to reintroduce genetic variation at selective sweeps or introgress novel allelic variation from close species, B. rapa and B. oleracea, into modern B. napus. (Xu et al 2019).…”

Exploration of incompatible crosses in plants for novel and useful variations

“…SRAP (sequence‐related amplified polymorphism) is an open reading frame‐based marker system and hence targets functional genes that was used in Brassica × Raphanus crosses, and all the progeny was confirmed as hybrids along with cytological observation (Zhan et al, 2017). Xu et al (2019) used SRAP markers to identify the paternal introgressions and novel DNA bands in the intergeneric hybrids of Brassica rapa and Orychophragmus violaceus . Chromosome‐specific STS, SSR, and gene‐specific markers, one for each of all seven barley chromosomes, were used in a population of 210 intergeneric wheat–barley cross derivatives, which revealed random nature of uniparental elimination for barley chromosomes without preferential elimination for any individual barley chromosome (Polgári et al, 2019).…”

“…SRAP (sequence-related amplified polymorphism) is an open reading frame-based marker system and hence targets functional genes that was used in Brassica  Raphanus crosses, and all the progeny was confirmed as hybrids along with cytological observation (Zhan et al, 2017). Xu et al (2019) used SRAP markers to identify the paternal introgressions and novel DNA bands in the intergeneric hybrids of Brassica rapa and Orychophragmus violaceus.…”