Abstract
One-hundred and nineteen progeny plants of crosses between one Hordeum lechleri (2n = 6x = 42) accession and the barley varieties 'Wong' and 'Igri' comprised 54 euploids (2n = 28), 8 hyperploids (2n = 29), 46 hypoploids (2n = 22 - 27), and 11 polyhaploids (2n = 21). Giemsa C-banding showed most interplant chromosome variation to be caused by elimination or, more seldom, duplication of barley chromosomes. The chromosomes of 'Wong' were preferentially lost in the order, 1H-4H-5H-3H-7H-2H-6H (5-4-7-3-1-2-6); those of 'Igri' in the order, 1H-3H or 6H-7H or 5H or 4H-2H (5-3 or 6-1 or 7 or 4-2), indicating different patterns of elimination. Over years chromosome elimination may be continuous. Hypoploid genomes of 'Wong' had the chromosomes arranged in the order, 1H-5H-2H-6H-7H-3H-4H (5-7-2-6-1-3-4), with a discontinuity between chromosomes 1H(5) and 4H(4); whereas in 'Igri' the order was (1H)-5H-2H-4H-7H-6H-3H-(1H) ((5)-7-2-4-1-6-3-(5)) with a discontinuity at 1H(5), indicating varietal differences. The patterns of barley chromosome elimination may be derived from chromosome orders. Elimination starts with a chromosome at the discontinuity, continues with the chromosome at the other end of the order, and proceeds more or less alternately towards the middle. In hybrids including 'Wong', duplication affected the two chromosomes situated at either end of barley chromosome order. A few older hybrids with 2n = 21 had three or four H.lechleri chromosomes substituted for as many barley chromosomes suggesting homoeology. Our observations support the hypothesis of an orderly arrangement of the chromosomes within genomes (Bennett 1981), but they do not agree with the idea of one 'natural karyotype' for each species (Bennett 1984b).Key words: Hordeum, interspecific hybrids, C-banding, chromosome elimination, chromosome order.
Published Version
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