An original meiotic mutation in Paspalum regnellii

Abstract

Cytogenetic studies carried out over a period of 2 consecutive years on a native Brazilian accession of Paspalum regnellii (2n=40) revealed a meiotic mutation that has not been previously reported for any other species. Among 13 inflorescences investigated during the first collection year, three presented anomalous meiotic behavior starting from metaphase I. At the beginning of this phase, the chromosomes occupied the entire equatorial plate in a membrane-to-membrane arrangement, and the spindle fibers, which were clearly visible, did not converge towards the poles. Degeneration of spindle fibers occurred at the end of metaphase I. Chromosome segregation did not occur and the bivalents were left scattered at random in the cytoplasm. Remnants of chromosome fibers could be seen close to the centromere during this stage. The bivalents gave origin to micronuclei in telophase I, with extremely wide variations in number and size among cells. With the absence of spindle formation during meiosis II, metaphase and anaphase II were not observed. Second cytokinesis occurred in prophase II cells after the occurrence of first cytokinesis. The final product of meiosis was completely abnormal, with a predominance of polyads with microspores of different sizes that resulted in abortive pollen grains. In the affected inflorescences, all microsporocytes presented this anomaly, which caused total sterility.

Meiotic behavior of economically important plant species: the relationship between fertility and male sterility

“…Another original meiotic mutation was described in Paspalum regnellii by Pagliarini et al (1998), which, in many aspects, is similar to that described by Taschetto and Pagliarini (1993) in maize. In the P. regnellii mutant there was spindle formation with the bivalents arranged at the equatorial plate as in normal metaphase I, but the spindle fibers did not converge towards the poles, instead there was degeneration of spindle fibers at the end of metaphase I and chromosome segregation did not occur, with the bivalents remaining scattered at random in the cytoplasm and remnants of chromosome fibers could be seen close to the centromere during this stage.…”

Chromosome numbers and meiotic behavior of some Paspalum accessions

“…Cytological analyses have been performed on more than 80 accessions from the CPPSE collection (Freitas et al, 1997;Takayama et al, 1998;Adamowski et al, 1998Adamowski et al, , 2000Pagliarini et al, 1998Pagliarini et al, , 1999Pagliarini et al, , 2000Pagliarini et al, , 2001 and the data presented in the present paper extends this study to a further 36 previously unanalyzed Paspalum accessions, including P. notatum Fluegge, P. compressifolium Swallen, P. usterii Hack., P. plicatulum Michx., P. atratum Swallen, P. coryphaeum Trin., P. lividum, P. rhodopedum L. B. Smith & Wasshausen, P. limbatum Henrard, P. conspersum Schrad and unidentified accessions belonging to the Plicatula group. The Plicatula group is an unofficial taxonomic rank created by Chase (1929) to group species related to P. plicatulum, this group having its geographical center of variation in central and western Brazil, eastern Bolivia and Paraguay .…”

Microsporogenesis in the endangered species Cupressus dupreziana A. Camus: evidence for meiotic defects yielding unreduced and abortive pollen

“…The exact cytological dysfunction responsible for the meiotic defects reported here have not been elucidated but it is likely that the spindle system is involved. Similar meiotic defects have been reported to occur sporadically in the conifers Picea abies (Andersson 1947) and Pinus silvestris (Runquist 1968), and in some angiosperms such as Zea mays (Staiger and Cande 1993) and Paspalum regnellii (Pagliarini et al 1998). In Fig.…”