ACCESSORY CHROMOSOMES INPAMCUM COLORATUM

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Abstract
Panicum coloratum, commonly called kleingrass, was introduced from South Africa and is being investigated as a potential forage grass in Texas. Accessory chromosomes were found in 27 of 79 tetraploid plants, but none was found in the 3 diploids studied. The paper reports the meiotic behavior of the tetraploids having accessory chromosomes. The unreduced chromosome number of tetraploid kleingrass is 36 with metaphase I pairing relationships of 14 bivalents and 2 quadrivalents. Plants were found having one to four accessories present. The accessories were never seen to pair with each other, but frequently showed secondary association with chromosomes of the normal complement. The accessories divided in meiosis I and a limited build-up of accessory chromosome numbers in progeny was observed. Precocious division and random distribution of accessory chromosomes to members of the tetrad cells occurred. Accessory chromosomes were sometimes accompanied by loose pairing and chromatid division of chromosomes of the normal complement during meiosis I. A possible origin of accessory chromosomes from lagging univalents of the regular complement was postulated.