Hazelcrestmikeb said:The day lily Apophis (http://rockhavendaylilies.com/... ), have by all reports reduced gamete, which is why from what I have read it can pollinate both diploids and tetraploids. I am no Admmad, when it comes to the intricacies of these matter. Just passing on this info.
Mike, it is theoretically possible that there are daylily cultivars that produce some "unreduced gametes". 'Ed Murray' might be one. However, Arisumi made a large number of diploid x tetraploid crosses and he basically examined the frequency at which such gametes might occur. His results indicate that one must make thousands of pollinations to possibly find one unreduced gamete and in doing so the number of triploids produced would swamp the rare tetraploid produced.
In doing crosses that work only if there are unreduced gametes there is a very important possibility that one must eliminate, and that is natural pollinations. In most modern cultivars hybridizers have modified the flower opening times, fragrances, sizes, etc., with the end result that natural pollinations are infrequent. But that is not the case for the original species daylilies and plants not many generations removed from the species. In those cultivars natural pollinations can occur at high frequencies before the hybridizer makes their own hand pollinations. That is the case for
Hemerocallis citrina and daylilies descended from it. Mahieu used citrina and other species in his hybridizing. I strongly suspect that the success of diploid x tetraploid crosses when a Mahieu cultivar is used as the pod parent is due to natural pollinations. The next most likely situation, if the seedlings are not simply diploids, is that they are triploids, which does not involve unreduced gametes. The least likely situation is that the seedlings are tetraploids from unreduced gametes. In any case, it would require chromosome counts or DNA analysis to correctly identify the ploidy of any seedlings produced from cross-ploidy pollinations.
A reduced gamete is the correct gamete. A diploid with 22 chromosomes produces normal gametes with 11 chromosomes - the reduced number. If it produces unreduced gametes then those gametes will have 22 chromosomes - the unreduced number.
In Arisumi's research he managed to produce one tetraploid (from unreduced gametes) and 11 triploids (from normal gametes) from an average of 1300 pollinations. Even when using a cultivar that may produce unreduced gametes, such as 'Ed Murray', it requires many pollinations to produce a single tetraploid viable seed.
Anyone interested in trying diploid x tetraploid crosses should make certain that they use 'safe' (Whatley) hybridizing techniques (
http://www.daylilies.org/Whatl...) that prevent or reduce natural pollinations. Even in modern cultivars that do not have frequent natural pollinations, when one is searching for a rare occurrence, such as a tetraploid produced from an unreduced gamete, even a rare natural pollination can trick one. As an example, 'Lights of Detroit' (LOD) is rumored to produce unreduced gametes. Whatley did a large test of LOD with many pollinations. He used fifty LOD plants, 25 were pollinated only with diploid pollen and 25 were pollinated only with tetraploid pollen. There were three pods produced from the plants pollinated with tetraploid pollen (the diploid pollen crosses were prolific). Of those three pods only one had viable seed and they produced diploids. There is no reliable evidence that LOD produces unreduced gametes; reliable evidence indicates that it does not.
