Fig. 2.

FISH and GISH analyses revealed the meiotic chromosome pairing of Paphiopedilum interspecific F₁ hybrids. Meiotic chromosomes were counterstained with DAPI in blue (A, D, G, J, M). Merged images of GISH/FISH results (B, E, H, K, N) show the chromosomes from P. delenatii (in green) and the locations of 45S rDNA loci (in red) of each hybrid. Chromosomes in same/similar configurations were grouped and are separately indicated by arrows in different colours (C, F, I, L, O). (A–C) Chromosome configuration (4I + 11II) at meiotic MI of the hybrid P. delenatii × P. micranthum (2n = 2x = 26). In (B) two univalents (arrows) with an 45S rDNA cluster (red), which originated from each parental genome, are shown. The two univalents without green signals indicated by arrowheads were from P. micranthum. (D–F) Chromosome configuration (8I + 9II) at meiotic late MI of the hybrid P. delenatii × P. bellatulum (2n = 2x = 26). In (E) arrowheads indicate the univalents from P. delenatii and arrows indicate the univalents from P. bellatulum. (G–I) Chromosome configuration (7I + 8II + 1III) at MI of meiosis in the hybrid P. delenatii × P. rothschildianum (2n = 2x = 26). Among the eight bivalents shown in (H), one was the autosyndetic pair of P. delenatii (arrow), three were autosyndetic pairs of P. rothschildianum (arrowheads) and four were homeologous pairs between parents (red arrows). One trivalent is indicated with a green arrow. (J–L) Chromosome configuration (6I + 4II + 5III) at MI of meiosis in the hybrid P. delenatii × P. callosum (2n = 2x = 29). In (K) arrows indicate the trivalents and the arrowhead indicates one P. callosum autosyndetic pair. (M–O) Chromosome configuration (5I + 5II + 4III + 1IV) at MI of meiosis in the hybrid P. delenatii × P. glaucophyllum (2n = 2x = 31). In (N) arrows indicate the trivalents and an arrowhead indicates the quadrivalent. Scale bars = 10 µm