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Meiosis of Coronilla varia L.¹

Meiosis in microsporocytes was studied in nine ‘Chemung’ plants, 14 ‘Penngift’ plants, and one S₁ plant of crownvetch (Coronilla varia L.). All plants were tetraploid (2n=24), and 41% of the diakinesis cells had one or more multivalents (III's or IV's). Averages of pairing configurations were 0.8 I's, 10.7 II's, 0.1 III's, and 0.4 IV's per cell. Quadrivalents ranged from 0 to 5 per cell, compared to a theoretical maximum of 6. We concluded that C. varia had autotetraploid-like meiotic chromosome behavior.

No differences were found between cultivars in mean frequencies of configurations per cell. However, plants within cultivars differed significantly in their frequencies of I's per cell (0.2 to 1.8), and in their proportions cells free of I's or III's (33 to 94%). The mean chiasma frequency among all plants was 1.1 chiasmata per biva-lent-equivalent (range 1.0 to 1.3).

Laggards were present at meiotic anaphases. Chromosome numbers at TI were largely euploid (n = 12). No micronuclei occurred in pollen quartets, thus laggard chromosomes may have been included in TII nuclei. A first generation inbred plant was much more irregular in meiosis than other plants studied.

Cytomixis was a sporadic occurrence in micxosporocytes of a few collections.

Key Words: Crownvetch • Chromosome cytology • Autotetraploidy • Chiasma frequency • Chromosome pairing • Chromosome number

² Former Graduate Research Assistant (now Systems Programmer, IBM Corporation, Poughkeepsie, N. Y.), and Associate Professors of Plant Breeding, The Pennsylvania State University, University Park, Pa., respectively.

Received for publication April 14, 1973.