Influence of Zinnia angustifolia HBK genotype on embryonic and vegetative development of Z. angustifolia x Z. elegans Jacq. interspecific hybrids

Abstract

Interspecific crosses between Zinnia angustifolia clones (maternal parents) and Z. elegans lines (paternal parents) were performed to investigate postzygotic barriers among Z. angustifolia X Z. elegans hybrids and to determine influence of parental genotype on embryonic and vegetative development of interspecific hybrids. Variation in percentage of emerged seedlings (PES) and percentage of morphologically normal hybrids (PNH) was attributable to Z. angustifolia clones with minor or no effect attributable to Z. elegans lines. Heterogeneity in PES values among Z. angustifolia clones was due to differences in amount of hybrid embryo breakdown and ungerminable seed. Cytological observations of normal and abnormal interspecific hybrids revealed similar chromosome numbers (2n=23) but indicated a low mitotic index for abnormal hybrids. Genetic analysis of PES and PNH suggested control by multiple genes inherited from the Z. angustifolia genome. Adequate sampling of the Z. angustifolia gene pool would permit exploitation of genetic variability present within the species and allow improvements in PES and PNH for interspecific hybrids.

Effect of Zinnia angustifolia HBK genotype on morphology and flowering of Z. angustifolia × Z. elegans Jacq. hybrids

“…elegans were used as parental material . Seedlings of Z. angustifolia were randomly selected from 2 commercial cultivars (Boyle et al ., 1987) and asexually propagated (cloned) by rooting terminal shoot cuttings . Three seedlings (AO1, A03, and A04) were cloned from 1 cultivar (Z .…”

“…Data were used as criteria in distinguishing phenotypically normal from abnormal interspecific hybrids (Boyle et al ., 1987) . Statistical analysis was performed on data from phenotypically normal hybrids .…”

“…angustifolia genotype on hybrid morphology and flowering Two populations were produced from reciprocal crosses between Z. angustifolia clones AW1 and AW2, and 9 F, progeny from each population were selected randomly and cloned (Boyle et al ., 1987) . To minimize border effects, data were collected on 35 plants in the 5 inner rows .…”

“…Interspecific hybrids between Cucumis zeyheri and C. sativus (Custers & Den Nijs, 1986), Nicotiana repanda and N. tabacum (Pittarelli & Stavely, 1975), Trifolium nigrescens and T. repens (Hoven, 1962), Vigna radiata and V. umbellata (Chen et al ., 1983) . and Zinnia angustifolia and Z. elegans (Boyle et al ., 1987) have been obtained by identification and utilization of parental lines or clones which significantly improved crossability . Among intergeneric matings, Harlan & de Wet (1977) crossed `dozens' of Tripsacum dactyloides clones with Zea mays and identified only one T. dactyloides clone capable of generating F, progeny .…”

“…Variation in percentage of emerged (hybrid) seedlings (PES) and percentage of morphologically normal hybrids (PNH) was attributable to Z. angustifolia genotypes used as maternal parents, with minor or no effect due to Z . elegans inbred lines used as paternal parents (Boyle et al ., 1987) . Heterogeneity in PES values among families derived from Z .…”