Meiotic behaviour in the first interspecific hybrids between Brachiaria brizantha and Brachiaria decumbens

• Published in: Plant breeding 2010-04, Vol.129 (2), p.186-191
• Main Authors: deSouza-Kaneshima, A.M, Simioni, C, Felismino, M.F, Mendes-Bonato, A.B, Risso-Pascotto, C, Pessim, C, Pagliarini, M.S, doValle, C.B
• Format: Article
• Language: English
• Subjects: Agronomy. Soil science and plant productions; Biological and medical sciences; Brachiaria brizantha; Brachiaria decumbens; chaotic spindle; chromosome doubling; Fundamental and applied biological sciences. Psychology; Genetics and breeding of economic plants; genome separation; Interspecific and intergeneric hybridization, introgressions; interspecific hybrid; meiosis; Plant breeding: fundamental aspects and methodology; Urochloa brizantha; Urochloa decumbens
• ISSN: 0179-9541; 1439-0523
• DOI: 10.1111/j.1439-0523.2009.01674.x

With 2 figures and 1 table Brachiaria brizantha and Brachiaria decumbens constitute the two most widely used tropical forage species for cultivated pastures and support both beef and dairy cattle production in the tropics. Two apomictic cultivars -B. brizantha cv. 'Marandu' and B. decumbens cv. 'Basilisk'- cover more than 100 million hectares of cultivated pastures throughout Latin America and Southeast Asia. This paper discusses the cytogenetic data of the first successful attempt in obtaining interspecific hybrids between these two species. Artificial hybridization between two diploid (2n = 2x = 18) sexual accessions (B. brizantha, B105 x B. decumbens, D004) was performed in the greenhouse. Only three hybrids were recovered. One of them was treated with colchicine in tissue culture and two amphidiploid plants were obtained. Meiosis in the diploid genitors was quite normal, while in the diploid hybrid parental genome separation was observed together with some irregular chromosome segregation. Genome separation was also observed in several cells in the two 4n amphidiploid hybrids. In these, a high number of meiocytes with chromosomes chaotically spread in the cytoplasm was recorded during meiosis. The abnormalities observed compromised the meiotic products characterized by polyads. Chromosomes associated generally as bivalents but some association as quadrivalents in diakinesis in one of the amphidiploid hybrids indicates taxonomic proximity between these two species. Moreover, it indicates that introgression of desirable genes may be feasible between these two most important agronomic species of the genus.