为了说明遗传资源的特殊重要性以及它们在育种策略方面所起的特殊作用,让我们举例扼要地考察一番当今农业的一些特点、趋势和问题: 1.改良品种间的遗传背景越来越一致,因此有病、虫害袭击的危险; 2.改良品种在大面积上种植,潜伏着由单一的病害袭击向流行性转化的危险; 3.抗生物性胁迫的性能主要是由单基因控制的,因此易被病菌致毒基因的突变所克服; To illustrate the special importance of genetic resources and their particular role in breeding strategies, let us take a brief look at some of the features, trends and problems of today’s agriculture: 1. The genetic background of improved varieties is becoming more and more consistent , So the risk of disease and pest attacks; 2. The improved varieties planted in a large area, lurking the risk of a single disease attack to epidemic; 3. Antibiotic stress performance is mainly controlled by a single gene, therefore Easily susceptible to mutations in virulence genes;