Lee M
Iowa State University, USA.
Symp Soc Exp Biol. 1996;50:31-8.
DNA markers and genetic maps will be important tools for direct investigations of several facets of crop improvement and will provide vital links between plant breeding and basic plant biology. The markers and maps will become more important for increased crop production because plant genetics will be required to extend or replace extant management practices such as chemical fertilizers, pesticides, and irrigation (Lee, 1995). Despite the importance of the sorghum crop, comprehensive genetic characterization has been limited. Therefore, the primary goal of this research program was to develop basic genetic tools to facilitate research in the genetics and breeding of sorghum. The first phase of this project consisted of constructing a genetic map based on restriction fragment length polymorphisms (RFLPs). The ISU sorghum map was created through linkage analysis of 78 F2 plants of an intraspecific cross between inbred CK60 and accession P1229828 (Pereira et al., 1994). The map consists of 201 loci distributed among 10 linkage groups covering 1,299 cM. Comparison of sorghum and maize RFLP maps on the basis of common sets of DNA probes revealed a high degree of conservation as reflected by homology, copy number, and collinearity. Examples of conserved and rearranged locus orders were observed. The same sorghum population was used to map genetic factors (mutants and QTL) for several traits including vegetative and reproductive morphology, maturity, insect, and disease resistance. This presentation will emphasize analysis of genetic factors affecting plant height, an important character for sorghum adaptation in temperate latitudes for grain production. Four QTL for plant height were identified in a sample of 152 F2 plants (Pereira and Lee, 1995) whereas 6 QTL were detected among their F3 progeny. These observations and assessments of other traits at 4 QTL common to F2 plants and their F3 progeny indicate some of these regions correspond to loci (dw) previously identified on the basis of alleles with highly qualitative effects. Four of the six sorghum plant height QTL seem to be orthologous to plant height QTL in maize. Other possible instances of orthologous QTL included regions for maturity and tillering. These observations suggest that the conservation of the maize and sorghum genomes encompasses sequence homology, collinearity, and function. The genetic information and technology developed on the basis of DNA markers could be used in several facets of breeding, genetics, and other basic biological investigations. In addition, DNA markers have been used to survey large collections of elite sorghum germ plasm to determine the degree of genetic relationships and genetic diversity (Ahnert et al., 1996). RFLP data seem to portray genetic relationships more accurately than the methods based exclusively on the coancestry coefficient. This information provides the basis for more accurate perceptions of genetic relationships and diversity.
DNA标记和遗传图谱将成为直接研究作物改良多个方面的重要工具，并将在植物育种与基础植物生物学之间建立至关重要的联系。随着作物产量的增加，这些标记和图谱将变得更加重要，因为植物遗传学将用于扩展或取代诸如化肥、农药和灌溉等现有的管理措施（Lee，1995）。尽管高粱作物很重要，但其全面的遗传特征分析却很有限。因此，本研究项目的主要目标是开发基础遗传工具，以促进高粱遗传学和育种方面的研究。该项目的第一阶段包括构建基于限制性片段长度多态性（RFLP）的遗传图谱。爱荷华州立大学的高粱图谱是通过对自交系CK60与种质P1229828之间种内杂交的78个F2植株进行连锁分析创建的（Pereira等人，1994）。该图谱由分布在10个连锁群中的201个位点组成，覆盖1299厘摩。基于一组共同的DNA探针比较高粱和玉米的RFLP图谱，发现了高度的保守性，这体现在同源性、拷贝数和共线性上。观察到了保守和重排的位点顺序实例。同一高粱群体被用于定位几个性状的遗传因子（突变体和QTL），包括营养和生殖形态、成熟度、抗虫性和抗病性。本报告将重点分析影响株高的遗传因子，株高是高粱在温带地区用于谷物生产的一个重要适应性性状。在152个F2植株样本中鉴定出4个株高QTL（Pereira和Lee，1995），而在其F3后代中检测到6个QTL。对F2植株及其F3后代共有的4个QTL处的其他性状进行的这些观察和评估表明，这些区域中的一些对应于先前基于具有高度定性效应的等位基因鉴定出的位点（dw）。六个高粱株高QTL中的四个似乎与玉米中的株高QTL是直系同源的。直系同源QTL的其他可能实例包括成熟度和分蘖区域。这些观察结果表明，玉米和高粱基因组的保守性包括序列同源性、共线性和功能。基于DNA标记开发的遗传信息和技术可用于育种、遗传学及其他基础生物学研究的多个方面。此外，DNA标记已用于对大量优良高粱种质进行调查，以确定遗传关系程度和遗传多样性（Ahnert等人，1996）。RFLP数据似乎比仅基于共同祖先系数的方法更准确地描绘遗传关系。这些信息为更准确地认识遗传关系和多样性提供了基础。
