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The frequency and meiotic behaviour of structural chromosome variants in natural populations of Allium schoenoprasum L. (wild chives) in Europe

1991; Springer Nature; Volume: 66; Issue: 3 Linguagem: Inglês

10.1038/hdy.1991.49

1365-2540

J P Stevens, S M Bougourd,

Plant Pathogens and Resistance

Meiotic analysis of 1017 plants of Allium schoenoprasum, sampled as adults from 18 natural populations in Britain and continental Europe, revealed that 35 (3.4 per cent) were heterozygous for one or more major structural chromosome mutations. Nineteen different interchanges, 11 different inversions, one deletion, and one supernumerary chromosome segment were found. There was no significant difference between British and continental European populations in the frequency of chromosomal variants. There was considerable variation in meiotic behaviour between different interchanges. On average, quadrivalent formation occurred in 68 per cent meiocytes, but the range (from 13 to 95 per cent) was wide. In five interchange heterozygotes, chiasma formation in the interstitial segments occurred in a high proportion of multivalents. In three interchange heterozygotes, a significant excess of chain quadrivalents were in alternate orientation. In the inversion heterozygotes, the frequency of reverse loop chiasma formation was relatively low, occurring, on average, in 6 per cent meiocytes (with a range from 3 to 13 per cent). The pollen and ovule fertilities of inversion heterozygotes were little affected, but those of many interchange heterozygotes were significantly depressed. The distribution of structural chromosome mutations throughout the genome was not random. A disproportionately high frequency involved the acrocentric, nucleolar-organizer chromosome pair.