FLOW CYTOMETRIC ANALYSIS OF GENOME SIZE VARIATION IN CULTIVATED AND WILD PISUM-SATIVUM (FABACEAE)

Fifteen cultivars, landraces, and wild accessions of Pisum sativum subspecies, and one accession of P. abyssinicum were analysed with flow cytometry (DAPI staining) using P. sativum 'Kleine Rheinlanderin' as internal standard. Applying the method of jointly isolating, staining, and measuring nuclei of individual seedlings of test and standard material, it was found that in all P. sativum comparisons G 1 and G 2 peaks were invariably unimodal and symmetric at coefficients of variation mostly less than 2%. This is strong evidence for absence of significant genome size variation in the P. sativum strains analysed. These data are markedly at variance to results of other authors reporting considerable genome size variation within P. sativum. However, in P. abyssinicum flow cytograms and Feulgen densitometric measurements indicate 4-8% more DNA, at same chromosome number (2n = 14), than in P. sativum. This result demonstrates that genome size variation is indeed existent in the genus and requires further examination.