Hoisington D, Jiang C, Khairallah M, Ribaut J M, Bohn M, Melchinger A, Willcox M, González-de-León D
CIMMYT, Int., Lisboa, Mexico.
Symp Soc Exp Biol. 1996;50:39-44.
Insects and drought cause severe losses in the production of maize in many developing countries. Conventional breeding efforts to enhance the level of resistance to a number of insect pests and tolerance to drought have been successful, although only through large efforts of many breeders and over a large period of time. Continued improvements will only be possible through substantial investment of resources. Recently, success in identifying quantitative trait loci (QTL) in several plant species using various molecular marker systems offers alternative methods for accelerating conventional breeding programs. As the first step towards using molecular markers in CIMMYT's maize breeding program, restriction fragment length polymorphisms (RFLPs) have been used to understand the genetic basis of resistance to two corn borer species, southwestern corn borer and sugarcane borer, and to one major component of drought tolerance, anthesis-silking interval. A number of QTL with effects large enough to be regarded as significant in breeding were detected for each of these traits and many of them presented stable effects over environments. While variability in the number and location of QTL has been found when compared across populations, several loci were found to be quite consistent. Simple calculations can be made which estimate that the total genetic potential in maize for these traits is high. It is argued that to ultimately access and manipulate this potential, the use of linked molecular markers as indirect selectable markers is both feasible and necessary.
在许多发展中国家，昆虫和干旱给玉米生产造成了严重损失。尽管众多育种人员付出了巨大努力且历经漫长时间，但通过传统育种方法提高对多种害虫的抗性水平以及对干旱的耐受性已取得成功。只有投入大量资源，才有可能持续改进。最近，利用各种分子标记系统在几种植物物种中成功鉴定出数量性状基因座（QTL），为加速传统育种计划提供了替代方法。作为在国际玉米小麦改良中心（CIMMYT）玉米育种计划中使用分子标记的第一步，限制性片段长度多态性（RFLP）已被用于了解对两种玉米螟（西南玉米螟和甘蔗螟）的抗性以及对耐旱性的一个主要组成部分（开花-吐丝间隔）的遗传基础。针对这些性状中的每一个，都检测到了一些效应大到足以在育种中被视为显著的QTL，其中许多在不同环境下表现出稳定的效应。虽然在不同群体间比较时发现QTL的数量和位置存在变异性，但也发现了几个相当一致的基因座。通过简单计算可以估计出玉米中这些性状的总遗传潜力很高。有人认为，要最终挖掘和利用这一潜力，使用连锁分子标记作为间接选择标记既可行又必要。
