D'Andrea Luigi, Felber François, Guadagnuolo Roberto
Laboratoire de botanique évolutive, Institut de biologie, Université de Neuchâtel, Rue Emile-Argand 11, CP 158, 2009 Neuchâtel, Switzerland.
Environ Biosafety Res. 2008 Apr-Jun;7(2):61-71. doi: 10.1051/ebr:2008006. Epub 2008 May 30.
Hybridization and introgression between crops and wild relatives may have important evolutionary and ecological consequences such as gene swamping or increased invasiveness. In the present study, we investigated hybridization under field conditions between crop lettuce (Lactuca sativa) and its wild relative prickly lettuce (L. serriola), two cross-compatible, predominantly autogamous and insect pollinated species. In 2003 and 2004, we estimated the rates of hybridization between L. sativa and L. serriola in close-to-reality field experiments carried out in two locations of Northern Switzerland. Seeds set by the experimental wild plants were collected and sown (44 352 in 2003 and 252 345 in 2004). Progeny was screened morphologically for detecting natural hybrids. Prior to the experiment, specific RAPD markers were used to confirm that morphological characters were reliable for hybrid identification. Hybridization occurred up to the maximal distance tested (40 m), and hybridization rates varied between 0 to 26%, decreasing with distance. More than 80% of the wild plants produced at least one hybrid (incidence of hybridization, IH) at 0 m and 1 m. It equaled 4 to 5% at 40 m. In sympatric crop-wild populations, cross-pollination between cultivated lettuce and its wild relative has to be seen as the rule rather than the exception for short distances.
作物与其野生近缘种之间的杂交和基因渐渗可能会产生重要的进化和生态后果，如基因淹没或入侵性增强。在本研究中，我们调查了作物生菜（Lactuca sativa）与其野生近缘种刺叶莴苣（L. serriola）在田间条件下的杂交情况，这两个物种具有交叉亲和性，主要进行自花授粉，但也有昆虫传粉。2003年和2004年，我们在瑞士北部的两个地点进行了接近实际情况的田间试验，估计了栽培生菜和刺叶莴苣之间的杂交率。收集实验野生植株结的种子并播种（2003年为44352粒，2004年为252345粒）。对后代进行形态学筛选以检测天然杂种。在实验之前，使用特定的随机扩增多态性DNA（RAPD）标记来确认形态特征对于杂种鉴定是可靠的。杂交发生在测试的最大距离（40米）以内，杂交率在0%至26%之间变化，并随距离增加而降低。超过80%的野生植株在0米和1米处产生了至少一个杂种（杂交发生率，IH）。在40米处，这一比例为4%至5%。在同域分布的作物-野生种群中，栽培生菜与其野生近缘种之间的异花授粉在短距离内应被视为常态而非例外。
