Kermicle Jerry L
Laboratory of Genetics, University of Wisconsin, Madison, Wisconsin 53706, USA.
Genetics. 2006 Jan;172(1):499-506. doi: 10.1534/genetics.105.048645. Epub 2005 Sep 12.
Some populations of maize's closest relatives, the annual teosintes of Mexico, are unreceptive to maize pollen. When present in the pistil (silk and ovary) a number of maize genes discriminate against or exclude pollen not carrying the same allele. An analogous gene Tcb1-s was found in some teosinte populations but not in sympatric or parapatric maize. It was polymorphic among populations of teosinte growing wild, but regularly present in populations growing in intimate association with maize as a weed. Introduction of Tcb1-s into maize substantially to fully restored compatibility with Tcb1-s carrying teosintes. Although Tcb1-s pollen can fertilize tcb1 tcb1 maize, it is at a competitive disadvantage relative to tcb1 pollen. Hence, the influence of Tcb1-s on crossability is bidirectional. In the absence of maize, Tcb1-s can increase in teosinte populations without improving their fitness. In the presence of maize, Tcb1-s appears to have been co-opted to provide reproductive isolation for adaptation to a cultivated habitat.
玉米的一些近亲种群，即墨西哥一年生类蜀黍，对玉米花粉不具有接受性。当存在于雌蕊（花丝和子房）中时，一些玉米基因会区分或排斥携带不同等位基因的花粉。在一些类蜀黍种群中发现了一个类似的基因Tcb1-s，但在同域或邻域的玉米中未发现。它在野生类蜀黍种群中具有多态性，但在与玉米作为杂草紧密伴生的种群中经常出现。将Tcb1-s导入玉米后，能基本完全恢复与携带Tcb1-s的类蜀黍的亲和性。尽管Tcb1-s花粉能使tcb1 tcb1玉米受精，但相对于tcb1花粉，它处于竞争劣势。因此，Tcb1-s对杂交亲和性的影响是双向的。在没有玉米的情况下，Tcb1-s在类蜀黍种群中可以增加而不提高其适合度。在有玉米的情况下，Tcb1-s似乎已被用于提供生殖隔离以适应耕种生境。
