Abstract
The objective of this work was to compare the meiotic behavior and pollen grain viability of three species of Crotalaria. Slides for meiotic analysis were prepared by the air-drying technique. Pollen grain viability was measured by three staining procedures (Alexander's solution, tetrazolium chloride and fluorescein diacetate) and in vitro germination in a sucrose solution. Eight bivalents were observed, confirming previous reports on populations from other regions of Brazil, as well as from other countries. All species showed abnormal meiotic behavior as follows: in Crotalaria micans, cytomixis and abnormal chromosome pairing in diakinesis; in C. spectabilis, abnormal chromosome pairing in diplotene; in C. zanzibarica, shrunk nuclei in leptotene and zygotene. Pollen grains of all three species show low viability, which may be associated with the irregularities of the meiotic behavior.
Highlights
Crotalaria L. belongs to the tribe Crotalarieae and is the third largest genus of the subfamily Faboideae (Fabaceae), comprising around 600 herbaceous and shrub species distributed in the tropics and subtropics (Polhill, 1982)
Vouchers were deposited at the herbarium of Universidade Federal de Lavras (ESAL): C. spectabilis Roth, five accessions from Ijaci (21o11'15"S, 44°56'15"W) (ESAL voucher number 22066); C. zanzibarica Benth, ten accessions from Ijaci (21o11'15"S, 44°56'15"W) (ESAL voucher number 22067); and C. micans Link, ten accessions from Lavras (21o14'43"S, 44°59'59"W) (ESAL voucher number 22070)
Ring and rod bivalents were detected in 0.33% diakineses for C. zanzibarica (Figure 1 D) and in 0.73% diakineses for C. spectabilis (Figure 1 F)
Summary
Crotalaria L. belongs to the tribe Crotalarieae and is the third largest genus of the subfamily Faboideae (Fabaceae), comprising around 600 herbaceous and shrub species distributed in the tropics and subtropics (Polhill, 1982). Information on chromosome number, quantitative karyotype parameters, chromosome banding patterns and rRNA gene mapping have been used for phylogenetic and chromosome evolution inferences in Crotalaria (Oliveira & Aguiar-Perecin, 1999; Mondin, 2003; Tapia-Pastrana et al, 2005; Almada et al, 2006; Flores et al, 2006; Mondin et al, 2007). Verma & Raina (1980) evaluated twenty species and observed chromosome stability based on predominance of normal bivalents, and related the occurrence of univalents, multivalents, and bridges with or without fragments in some species. These irregularities were considered as evidence for structural changes during the evolution of the genus
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