Snow A, Moran-Palma P, Rieseberg L, Wszelaki A, Seiler G
Am J Bot. 1998 Jun;85(6):794.
Crop-to-wild hybridization has the potential to introduce beneficial traits into wild populations. Gene flow from genetically engineered crops, in particular, can transfer genes coding for traits such as resistance to herbicides, insect herbivores, disease, and environmental stress into wild plants. Cultivated sunflower (Helianthus annuus) hybridizes spontaneously with wild/weedy populations (also H. annuus), but little is known about the relative fitness of F1 hybrids. In order to assess the ease with which crop-to-wild introgression can proceed, we compared characteristics of F1 wild-crop progeny with those of purely wild genotypes. Two nontransgenic, cultivated varieties were crossed with wild plants from three different regions-Texas, Kansas, and North Dakota. Seed burial experiments in the region of origin showed that wild-crop seeds had somewhat higher germination rates (less dormancy) than wild seeds from Kansas and North Dakota, while no differences were seen in seeds from Texas. Progeny from each type of cross were grown in outdoor pots in Ohio and in a weedy field in Kansas to quantify lifetime fecundity and flowering phenology. Flowering periods of hybrid and wild progeny overlapped considerably, especially in plants from North Dakota and Texas, suggesting that these hybrids are very likely to backcross with wild plants. In general, hybrid plants had fewer branches, flower heads, and seeds than wild plants, but in two crosses the fecundity of hybrids was not significantly different from that of purely wild plants. In Ohio, wild-crop hybrids from North Dakota appeared to be resistant to a rust that infected 53% of the purely wild progeny, indicating a possible benefit of "traditional" crop genes. In summary, our results suggest that F1 wild-crop hybrids had lower fitness than wild genotypes, especially when grown under favorable conditions, but the F1 barrier to the introgression of crop genes is quite permeable.
作物与野生植物杂交有可能将有益性状引入野生种群。特别是来自转基因作物的基因流动，可以将编码抗除草剂、抗食草昆虫、抗病和抗环境胁迫等性状的基因转移到野生植物中。栽培向日葵（Helianthus annuus）会与野生/杂草种群（也是H. annuus）自然杂交，但对于F1代杂种的相对适合度了解甚少。为了评估作物基因向野生植物渗入的难易程度，我们将F1代野生作物后代的特征与纯野生基因型的特征进行了比较。将两个非转基因栽培品种与来自德克萨斯州、堪萨斯州和北达科他州三个不同地区的野生植物进行杂交。在原产地进行的种子掩埋实验表明，野生作物种子的发芽率略高于来自堪萨斯州和北达科他州的野生种子（休眠期较短），而来自德克萨斯州的种子未观察到差异。每种杂交类型的后代在俄亥俄州的室外花盆和堪萨斯州的杂草丛生的田地中种植，以量化其一生的繁殖力和开花物候。杂种和野生后代的花期有很大重叠，特别是来自北达科他州和德克萨斯州的植株，这表明这些杂种很可能与野生植物回交。总体而言，杂交植物的分枝、花头和种子比野生植物少，但在两次杂交中，杂种的繁殖力与纯野生植物没有显著差异。在俄亥俄州，来自北达科他州的野生作物杂种似乎对一种锈病具有抗性，这种锈病感染了53%的纯野生后代，这表明“传统”作物基因可能具有益处。总之，我们的结果表明，F1代野生作物杂种的适合度低于野生基因型，特别是在有利条件下生长时，但作物基因渗入的F1障碍相当容易突破。
