Abstract
This paper reports a case of abnormal spindle orientation during microsporogenesis in an interspecific hybrid of the tropical grass Brachiaria. In the affected plant, prophase I was normal. In metaphase I, bivalents were regularly co-oriented but distantly positioned and spread over the equatorial plate. In anaphase I, chromosomes failed to converge into focused poles due to parallel spindle fibers. As a consequence, in telophase I, an elongated nucleus or several micronuclei were observed in each pole. In the second division, the behavior was the same, leading to polyads with several micronuclei. A total of 40% of meiotic products were affected. The use of this hybrid in production systems needing good-quality seeds is discussed.
Highlights
This paper reports a case of abnormal spindle orientation during microsporogenesis in an interspecific hybrid of the tropical grass Brachiaria
In this paper we report the spontaneous occurrence of an abnormality affecting spindle orientation in an interspecific hybrid between Brachiaria ruziziensis and Brachiaria brizantha
We cytogenetically investigated the apomictic Brachiaria hybrid between a B. brizantha (2n = 4x = 36) as pollen donor and B. ruziziensis (2n = 4x = 36), an artificially tetraploidized sexual accession which complements some agronomic characteristics lacking in B. brizantha
Summary
In this paper we report the spontaneous occurrence of an abnormality affecting spindle orientation in an interspecific hybrid between Brachiaria ruziziensis and Brachiaria brizantha. The Hb 19 hybrid was synthesized in 1988 by the Brazilian research organization ‘Embrapa Beef Cattle’ (Campo Grande, MS, Brazil) and is still undergoing agronomic evaluation, the genotype being a single plant that grown in a tuft under controlled phytosanitary conditions in the Brachiaria germplasm collection at Embrapa Beef Cattle.
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