Meiotic behaviour in the first interspecific hybrids between Brachiaria brizantha and Brachiaria decumbens
Meiotic behaviour in the first interspecific hybrids between Brachiaria brizantha and Brachiaria decumbens
复制标题
DOI：
10.1111/j.1439-0523.2009.01674.x
复制
发表时间：
2010-04-01
期刊：
影响因子：
2
通讯作者：
do Valle, C. B.
中科院分区：
文献类型：
--
作者：
de Souza-Kaneshima, A. M.;Simioni, C.;do Valle, C. B.
P>Brachiaria brizantha 和 Brachiaria decumbens 是栽培牧场中使用最广泛的两种热带饲料品种，支持热带地区的肉牛和奶牛生产。两个无融合生殖品种-B。布里赞萨CV. 'Marandu' 和 B. decumbens cv。 “蛇怪”——覆盖拉丁美洲和东南亚超过 1 亿公顷的耕地。本文讨论了首次成功尝试获得这两个物种之间的种间杂交的细胞遗传学数据。在温室中进行了两个二倍体 (2n = 2x = 18) 有性种质 (B. brizantha, B105 x B. decumbens, D004) 之间的人工杂交。仅回收了三个杂交种。其中一株在组织培养中用秋水仙碱处理，获得两株双二倍体植株。二倍体生殖细胞中的减数分裂是相当正常的，而在二倍体杂种亲本基因组中观察到分离以及一些不规则的染色体分离。在两个 4n 双二倍体杂种的几个细胞中也观察到基因组分离。在这些细胞中，在减数分裂过程中记录到大量的性母细胞，其染色体混乱地分布在细胞质中。观察到的异常损害了以多分体为特征的减数分裂产物。在双二倍体杂种之一中，染色体通常以二价形式关联，但在终变过程中某些以四价形式关联，表明这两个物种之间在分类学上的接近性。此外，它表明所需基因的渗入在该属的这两个最重要的农艺物种之间可能是可行的。
P>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.