Gakpetor P M, Mohammed H, Moreti D, Nassar N M A
Hawassa University, Hawassa, Ethiopia.
Empresa Matogrossense de Pesquisa, Assistência e Extensão Rural, , Brasil.
Genet Mol Res. 2017 Sep 21;16(3):gmr-16-03-gmr.16039790. doi: 10.4238/gmr16039790.
Plant interspecific periclinal chimeras are a mosaic formed by tissues from two species. They are manipulated here as an efficient plant breeding tool for cassava root yields. In this study, plants synthesized from two chimeras, designated as chimera 2 and chimera 4, were characterized morphologically and cytologically to unravel the origin of their tissue layers (L2 and L3). Root yield of the two chimeras was also evaluated. Chimera 2 that was developed from graft union between Manihot fortalezensis (F) as scion and M. esculenta (E) as rootstock and the same in chimera 4 was developed from grafting triploid cassava cultivar (2n = 54) (C) as scion and M. pohlii (P) (2n = 36) as rootstock. A new method of inducing interspecific chimeras without using hormones was also tested in this study. Five combinations between four cassava cultivars on one side and M. fortalezensis and an interspecific hybrid (M. glaziovii x M. esculenta) on the other side were experimented to determine compatibility between the parents. Wild species always gave L2 and L3, independent of being used as rootstock or scion. L3 is responsible for producing pericycle. Thus, its performance was different in each chimera due to specific epigenetic interaction. Of 48 grafts, it was obtained one chimera giving a percentage of 2.1% that is little lower than using hormones but much efficient to use. Chimera induction efficiency in this investigation was the same when using hormones. Thus, our new, less labor, and more cost-effective technique is as much efficient as hormones and is much potential to employ as an effective plant breeding method boosting cassava root yield.
植物种间周缘嵌合体是由两个物种的组织形成的嵌合体。在此，它们被作为提高木薯块根产量的有效植物育种工具加以利用。在本研究中，对由两种嵌合体（命名为嵌合体2和嵌合体4）合成的植株进行了形态学和细胞学特征分析，以揭示其组织层（L2和L3）的起源。还评估了这两种嵌合体的块根产量。嵌合体2由以福氏木薯（F）为接穗、食用木薯（E）为砧木的嫁接组合发育而成，嵌合体4则由以三倍体木薯品种（2n = 54）（C）为接穗、波氏木薯（P）（2n = 36）为砧木的嫁接组合发育而成。本研究还测试了一种不使用激素诱导种间嵌合体的新方法。对一方的四个木薯品种与另一方的福氏木薯和一个种间杂种（巴西木薯×食用木薯）之间的五种组合进行了试验，以确定亲本之间的亲和性。野生种总是提供L2和L3，无论用作砧木还是接穗。L3负责产生中柱鞘。因此，由于特定的表观遗传相互作用，其在每个嵌合体中的表现有所不同。在48次嫁接中，获得了1个嵌合体，成功率为2.1%，略低于使用激素的情况，但使用起来效率更高。本研究中使用激素时嵌合体诱导效率相同。因此，我们这种新的、省力且更具成本效益的技术与激素一样高效，并且作为一种提高木薯块根产量的有效植物育种方法具有很大的应用潜力。
