Meiotic instability in invader plants of signal grass <em>Brachiaria decumbens</em> Stapf (Gramineae)

Abstract

Brachiaria decumbens is a tropical grass, native of the African savannas, with a narrow natural distribution. On the other hand, B. decumbens cv. Basilisk is a perennial forage grass widely used for pasture in the tropics. This cultivar was introduced in Australia in 1930 and thence to Brazil in the 60s. Although it covers millions of hectares in the country, it is considered a weed outside the pasture environment. Invader plants of B. decumbens, probably of the cultivar Basilisk, were collected on the grounds of the State University of Maringá, PR, and cytologically analyzed. Meiotic abnormalities were recorded with great frequency, some of which had been previously reported neither for B. decumbens nor for other Brachiaria species. Among the irregularities, abnormal chromosome segregation, desynapsis, chromosome stickiness and fusional syncytes were reported. The influence of the meiotic instability in causing pollen sterility is discussed