Method Development for Applying Pollen Selection in Cucumber Breeding Programmes: Effects of Centrifugation on Pollen Competence

Abstract

The possibility to use large populations of haploid genomes makes pollen a potentially efficient plant system to select for sporophytes bearing favorable traits. Screening pollen for sporophytic features is only possible if genes responsible for the particular traits are also expressed during microgametophyte development. Tanksley et al. (1981) and Willing and Mascarenhas (1984) showed that about 60 % of the genes are correspondingly expressed in the gametophytic and sporophytic life cycle of the plant. Overlap in gene expression is also evident from the parallel responses in pollen and plants for tolerances and sensitivities for a wide range of agents (e.g., Mulcahy et al., 1985; Bino et al., 1987). In addition, pathogenesis related processes and mechanisms involved in disease resistance are expressed in both vegetative and generative tissues (Laughnan and Gabay, 1973; Bino et al., 1988). The potential of pollen selection in plant breeding programmes, however, depends on the development of methods for pollen manipulation. As discussed by Bino and Stephenson (1988), selection conditions and methods forseparation and concentration of selected from non- selected pollen have to be optimized, while techniques for the application (pollination) of manipulated microgarnetophytes on pistils insuring fertilization need to be improved.