Genome size variation in Pisum sativum

Pisum sativum L. is one of the plant species where infraspecific genome size variation, up to 1.29-fold between cultivars, has been reported. The present investigation deals with a Feulgen cytophotometric analysis of this phenomenon in 25 wild accessions, landraces, and cultivars of widely different geographic origin. Differences between accessions were maximally 1.054-fold in single experiments but proved to be nonreproducible upon repeated measurements. Seedlings of the same accession often differed significantly, up to 1.056-fold, but values from root and shoot tips in one individual were not significantly correlated, indicating the absence of true genome size variation between plants. Upon calibration against Allium cepa a 1C value of 4.42 pg is estimated for Pisum sativum. Altogether the data suggest that, contrary to the divergence in the literature data and recent reports on DNA content variation, the pea has a stable genome size.