Different fertility and meiotic regularity in allohexaploids derived from trigenomic hybrids between three cultivated Brassica allotetraploids and B. maurorum

Abstract

The wild species Brassica maurorum Durieu (MM, 2n = 16) is useful for the improvement of Brassica crops. Herein, interspecific reciprocal crosses between B. maurorum and three cultivated Brassica allotetraploids were carried out with the aid of embryo rescue. Trigenomic hybrids with Brassica napus (AACC, 2n = 38) and Brassica carinata (BBCC, 2n = 34) were produced from reciprocal crosses, but the hybrids with Brassica juncea (AABB, 2n = 36) were obtained only when B. maurorum was used as female. All the hybrids were morphologically intermediate between their parents, and were male and female sterile. By in vitro chromosome doubling of the trigenomic hybrids, the allohexaploids (AACC.MM/MM.AACC, 2n = 54; BBCC.MM, 2n = 50; MM.AABB, 2n = 52) were established and characterized for their phenotype and cytology. The fertilities of three allohexaploids were different, for AACC.MM and MM.AACC failed to produce seeds by selfing, but BBCC.MM showed low seed-set and MM.AABB had good seed-set. They also expressed variable extents of male meiotic regularity as to chromosome pairing and segregation, with MM.AABB > BBCC.MM > AACC.MM/MM.AACC, the same order as their fertility. So their meiotic behavior contributed to the fertility. Finally, the potential of these allohexaploids as a bridge for genetic improvement of Brassica crops was discussed.

Recreating Stable Brachypodium hybridum Allotetraploids by Uniting the Divergent Genomes of B. distachyon and B. stacei

“…Moreover, the success rate of interspecific hybridization in the present study was very low. This is similar to other species where parental genotypes have been shown to have a large effect on the success of interspecific hybridization [72–74]. …”

Cytoplasmic and Genomic Effects on Meiotic Pairing in Brassica Hybrids and Allotetraploids from Pair Crosses of Three Cultivated Diploids

“…But AA.CC had high pollen fertility while CC.AA had much lower fertility, which was possibly caused by the cytoplasmic effects. The differences in cytological behaviors in our synthetics could be explained partly by their genome relatedness as revealed by the chromosome pairing in respective dihaploid hybrids from which they were derived (Tables 1-4) and as shown by other Brassica allopolyploids (Yao et al 2012). The A-C bivalents in A.C were much higher than the A-B bivalents in A.B and the B-C bivalents in B.C.…”

Cloning and expression analysis of an anthocyanidin synthase gene homologue from Brassica carinata

“…Thus, it is an important germplasm resource for genetic improvement of rapeseed in China. By distant hybridization, its superior genes can be transferred into the widely cultivated rapeseeds (Yao et al 2012;Li et al 2007). In the present study, ANS gene was cloned from the cDNA in the seed coat of blackseeded B. carinata by homology cloning.…”