Crossability of <i>Brassica carinata</i> and <i>B. tournefortii</i>, and Cytomorphology of Their F₁ Hybrid

Abstract

Summary Reciprocal crosses between Brassica carinata (BBCC, 2n=34) and B. tournefortii (TT, 2n=20) were attempted in order to determine crossability between the species, carry out chromosomal associations among the B, C and T genomes, and to study morphology of the interspecific hybrids. A hybrid between these 2 species was obtained only when B. carinata was used as a female parent. Morphologically, the hybrid was intermediate between the progenitor species but its leaves resembled B. carinata. The F 1 plant was tall but grew very slowly. The hybrid was almost male sterile, showing only 2.3% pollen stainability. Meiotic studies of trigenomic triploid hybrid (BCT, 2n=27) showed various chromosome configurations including quadrivalents (0-1), trivalents (0-2), bivalents (2-9) and univalents (5-23). Only 5 univalents were recorded to have occurred; otherwise trivalents and bivalents were observed in pollen mother cells of the BCT hybrid. A few chromosomal association could be expected through allosyndesis which suggests the possibility of transferring genes across the species through interspecific hybridization.

Some Cytomorphological Evidence for Synthesis of Interspecific Hybrids between <i>Brassica juncea</i> and Autotetraploid <i>B. fruticulosa</i>

“…The F 1 hybrid plants thus obtained were observed to be intermediate in terms of many phenotypic features of both the parents. These observations are in congruence with earlier published reports (Chen et al 2011, Choudhary andJoshi 2012). The occurrence of characteristics from both progenitor species in the hybrids indicates that the F 1 plants inherited genomes of both parental species crossed.…”

“…Occasional laggards were recorded at anaphase I and II. Unequal distribution of chromosomes at anaphase I were recorded in few cells and in anaphase II few PMCs with laggards and one cell intermixing of chromatids at one pole was also encountered, it is similar to the study reported by Choudhary and Joshi (2012). Decrease in pollen fertility and reduced seed set recorded in the present hybrids might be due to meiotic irregularities and segregational anomalies (Singh 1993).…”

“…The observation of bivalents which ranged from 2-10 to 4-12 in various PMCs in the hybrids could be interpreted to be due to archaic homology within the chromosomes of the same genome or because of intergenomic homoeology. However, the occurrence of higher associations in the form of trivalents, their mean value ranged from 0.36 to 0.84 and that of quadrivalents ranged between 0.68 and 0.76 in F 1 hybrids can be attributed to allosyndesis indicating partial homoeology or segmental allopolyploidy between the two parental genomes (Choudhary andJoshi 2012, Prakash et al 2009). Thus, it appears that B. fruticulosa has some homoeology with B. juncea, indicating possibility of gene inrogression from B. fruticulosa (FFFF) to B. juncea via conventional breeding means.…”

Cytomorphological and Molecular Characterization of F₁ Hybrids between <i>Brassica tournefortii</i> and <i>B. rapa</i>

“…Unequal distribution of chromosomes at anaphase I was recorded in a few cells, which is similar to the study reported by Choudhary and Joshi (2012). The drastic decrease in pollen fertility and reduced seed set recorded in the present hybrids might be due to meiotic irregularities and segregational anomalies (Singh 1993).…”

Integration of cytological and molecular analysis to confirm a hybridity in F1 Brassica progeny

“…In this research, no relationship between characteristics of the pollen grains and meiosis or molecular results was observed. Similarly to other experiments, pollen viability was much lower in F1 hybrids than in the two parental species (Pertl et al, 2002, Choudhary & Joshi 2012. However, different shape of pollen grains did not affect the grains' viability.…”