Obtain inter-section hybrids between Primula forbesii (Sect. Monocarpicae) and P. saxatilis (Sect. Cortusoides)

Abstract To breed excellent cultivars with prosperous fragrant flowers, long flowering period, and high resistance to hardiness, three Primula forbesii (Sect. Monocarpicae) cultivars (2n=2x=18) and P. saxatilis (Sect. Cortusoides) (2n=2x=24) were used as parents for hybridization. Fourteen progenies were obtained from three cross combinations of P. forbesii as maternal parent by embryo rescue. Eventually, 12 progenies were proved to be true hybrids (2n=2x=21) by flow cytometry, chromosome counting and amplified fragment length polymorphism analysis. All the hybrids had long lasting flowering period just like P. forbesii, and their leaf back and scapes were not covered by white powder like P. saxatilis. The hybrid progenies were more similar to their male parent P. saxatilis by phenotypes analysis. Pollen of hybrids was abnormal and the germination rates were very low (3.18%–0.23%). Phenomena such as chromosome outside the equatorial plate, lagging chromosomes, chromosome bridges, micronucleus and polyads happened during the process of pollen mother cell meiosis, resulting pollen abortion finally. The results of backcrossing with their parents as pollen donators indicated that the pollen was able to germinate on the stigma surface and pollen tubes could extend into the hybrids’ ovules. It was showed that the inter-section hybrids could be used as female parent, but could not be used as pollen donator in continuing hybridization.