Genetische Versuche mit Collinsia. IV. Die Analyse eines nahezu sterilen Art-bastardes. 1. Die diploiden Bastarde zwischen Collinsia bicolor und C. bartsiaefolia. 2. Die polyploiden Bastarde zwischen Collinsia bicolor und C. bartsiaefolia
Hiorth, G.
Zeitschr Indukt Abstamm U Vererbungslehre 66(1-2): 106-157, 245-274
1933
Accession: 024745186
1. A cross C. bicolor (n = 7) X C. bartsiaefolia (n= 7) was obtained, but with low productivity; the reciprocal cross was more difficult to make. The reciprocal hybrids were phenotypically alike. The hybrids exhibited a high degree of sterility when backcrossed to either parent or when selfed. The F2 and F3 diploid plants were nearly self-sterile. One F2 plant was a fertile tetraploid. Meiosis was apparently normal in the hybrids. Many genie combinations in the hybrid gave viable ovules; fewer combinations were successful in the pollen. In one backcross to C. bicolor, nearly all the progeny were phenotypically bicolor. Selective fertilization was probably operative. Reciprocal cross-over classes were present in unequal frequencies. By repeated backcrosses, genes of one sp. were intercalated into the other sp. Such manipulation was more effective for some genes than for others.[long dash]2. Two unlike tetraploids (4n = 28), larger than the diploid plants, were obtained: (1) tB1, appeared in an F2 generation of C. bartsiaefolia (n = 7) X C. bicolor (n = 7) and bred true for 5 generations; (2) tB2, appeared in the progeny of a selfed individual which had arisen from a backcross of a nearly sterile plant. TB2 selfed gave 95% typical plants and 5% variants. The fertility of tB1 and tB2 was approximately the same,[long dash]25-50% that of C. bicolor or 10-20% that of C. bartsiaefolia. In selfing tB1, only a part of the viable ovules were fertilized. TB1 X C. bicolor gave nearly sterile triploid progeny. The reciprocal cross gave fertile tetraploids with 21 bicolor and 7 bartsiaefolia chromosomes; these, when selfed, produced a progeny resembling, with some exceptions, bicolor, C. bartsiaefolia X tB1 gave fertile tetraploids with 7 bicolor and 21 bartsiaefolia chromosomes; they resembled the bartsiaefolia plants, but were larger. TB1 X diploid F1 (bicolor X bartsiaefolia) gave tetraploids with 7 pairs of bicolor and 7 pairs of bartsiaefolia chromosomes; they resembled the tB1 line, but were less fertile. TB1 XtB2 gave progeny of intermediate appearance. The use of a nearly sterile hybrid in plant propagation is fully discussed.