Six F1's involving 6 multiple genetic marker stocks and a common inbred parent (PU812) were cultured to study the genotypic effect on regeneration ability and frequency of somaclonal variation in R0 for the known heterozygous marker genes. Leaf discs 7 mm in diameter were excised from young fully expanded leaves of 6-7 week old plants, and cultured on MS medium supplemented with cytokinins (Kinetin, Benzyladenine) and IAA. With few exceptions, the parents and F1's responded similarly to different hormone combinations. The beat hormone combinations for shoot formation were 4 mg/l Kinetin + 0.5 mg/l IAA and 2.3 mg/l BA + 0-0.18 mg/l IAA.Only 2 of the 6 multiple marker stocks and the common inbred parent (PU812) were successfully regenerated. Four of the six hybrids between PU812 and the multiple markers were readily regenerated, whereas 2 hybrids failed to regenerate with several different hormonal combinations. No mutations have been observed for the known heterozygous markers in 76 R0 tissue culture regenerants.
To find fertile garlic clones to be used in the cross breeding program, 213 accessions were subjected to cytological study at meiosis I. Most accessions (185 clones) showed abnormal chromosome configurations of ring of four, six or eight, which are ascribed to single or multiple translocations. Two clones showed asynaptic behavior forming 16 univalents from zygotene to metaphase I, and 26 clones revealed regular chromosome paring of 8 bivalents.Only six of 26 clones showing normal meiosis produced viable pollen grains, while the rest were male sterile. From the segregation of crosses between male sterile and fertile clones, the male sterility is presumed to be governed by single recessive gene.Hybrid plants between the fertile clones appeared, in general, intermediate of the parents in field performance.
Forty lines of gerbera (Gerbera hybrida) were developed by self-pollination of 80 commercial pot varieties. The lines show wide variation in both qualitative characters (flower and disk color) and quantitative characters (flower diameter, peduncle length and days to flowering). The inbred lines showed varying degrees of inbreeding depression in peduncle length and flower diameter as much as 66-88% and 89%, respectively. As selfed generations were advanced, the quantitative characters of lines became uniform as measured by variance among 30 individual plants per generation. It is postulated that a few number of genes are controlling flower color since most lines of third or fourth selfed generation showed uniform color. Hybrids between developed lines of third selfed gereration showed considerable level of heterosis in flower diameter, peduncle length, and number of flowers, and considerably lower degree of heterosis in days to flower.
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