Interspecific hybridization in Lonicera caerulea and Lonicera gracilipes: The occurrence of green/albino plants by reciprocal crossing

Lonicera caerulea L. var. emphyllocalyx (Maxim.) Nakai is a berry crop cultivated in cold regions. So far, commercial cultivars have been mainly introduced from selection of wild plants. Therefore, fruit traits and other agricultural characteristics have been limited. In this study, interspecific crosses between L. caerulea var. emphyllocalyx and Lonicera gracilipes var. glabra Miquel were examined to increase genetic variability of L. caerulea var. emphyllocalyx. Seedlings were obtained from reciprocal crosses between L. caerulea var. emphyllocalyx and L. gracilipes var. glabra. The hybrid nature of seedlings was confirmed with random amplified polymorphic DNA analysis. Viable green plants were obtained efficiently from L. gracilipes var. glabra × L. caerulea var. emphyllocalyx. In contrast, all plants produced from L. caerulea var. emphyllocalyx × L. gracilipes var. glabra were albino. These albino plants were very weak and only survived in culture condition. The chlorophyll deficiency was unilaterally observed, suggesting the occurrence of nuclear-cytoplasmic incompatibility. Viable F1 hybrids obtained from L. gracilipes var. glabra × L. caerulea var. emphyllocalyx are amphidiploid (2n = 4x = 36) as showing same to both parents. The hybrid plants are expected to increase the variability of fruit traits, and may have heat tolerance from L. gracilipes var. glabra.