Rapid Creation of Interspecific Hybrid Progeny to Broaden Genetic Distance through Double Haploid (DH) Inducer in Brassica napus

Abstract

Interspecific hybridization of rapeseed is an important way to innovate breeding resources. This research used Brassica napus and Brassica rapa for artificial synthesis interspecific hybridization of F1. The F1 self-fruiting rate was particularly low. By comparing the fertilization rate and seed setting rate of nine crosses and selfing combinations of interspecific hybrid progeny F1 and control B. napus, the results proved that the genetic stability of egg cells was greater than that of sperm cells, so the F1 could get seed by artificial pollination with other normal pollen. Based on these results, interspecific maternal inbred offspring (induced F1) from egg cells was obtained by emasculation and pollination with the pollen of DH inducer Y3380. It was found through morphological analysis, flow cytometry identification, and meiotic observation of induced F1, the plants had most normal fertile tetraploid and the meiosis was normal. The FISH results showed that the induced F1 were B. napus (2n = 4x = 38, AACC), 20 A and 19 C chromosomes. The results of SNP chip detection and genetic cluster analysis found that the genetic variation between interspecies could be preserved or broadened in the induced F1. The use of DH inducer created special breeding resources for interspecific hybridization and distant hybridization of rapeseed while shortening time, improving efficiency, and providing a new insight into innovate breeding resources.

Embryo Rescue in Plant Breeding

“…The ploidy level typical of the female plants used in the crosses was confirmed by flow cytometry and SNP chip technology. Building upon these previous results, Zhou et al [266] obtained interspecific maternal inbred offspring from egg cells of B. napus pollinated with the pollen of the DH inducer named Y3380. The FISH results confirmed that the obtained F 1 was B. napus (2n = 4x = 38, genome AACC).…”

“…In the genus Brassica, difficulties have often been encountered in obtaining welldeveloped embryos from interspecific hybridizations. For example, interspecific hybridization between Brassica napus and B. rapa resulted in a low hybridization rate [266]. A comparison between interspecific hybridization and self-fertilization materials demonstrated that egg cells' genetic stability was greater than sperm cells.…”

Paternal chromosome elimination of inducer triggers induction of double haploids in Brassica napus

“…We counted the fertilization rate 48 h after pollination. Fertilization rate percentage was calculated by the following formula: fertilization rate % = the number of ovules with fluorescent dots in the silique/total number of ovules in the silique × 100 ( Zhou et al., 2022 ).…”

Brassica napus Haploid and Double Haploid Production and Its Latest Applications

“…Zhang et al [88] developed cytoplasmic male sterile and maintainer lines of B. napus with the doubled haploid inducer allooctoploid lines Y3380 and Y3560 described above. Zhou et al [89] hypothesized that the new DH inducer lines can successfully replace the method of continuous backcrossing of interspecific F 1 with the parent to resolve the problem of low seed rate. Such difficulty is caused by hybrid sterility and chromosomal mismatch in the hybrid offspring of rapeseed.…”