INRA Frejus Dihaploid roses (dihaploids are diploids from tetraploids unfecundated gametes) were secured from embrio culture of unfecundated ovules whose development began using dead irradiated pollen.
That pollen may be helped by another mixed is called “mentor” effect.
Pollen mixture are a great help for advanced interspecific crosses with frequent compatibility and or fertility problems.
Its use is a shortcut for many trials and failures with transitional parents.
Pierre,
The mentor effect is important in some crosses. In addition, there is a maternal influence.
The seed parent cannot choose to provide extra nutrition to seeds with a superior genotype, of course. But it can “play the odds” by investing more heavily (supplying more nutrients) to fruit that have been fertilized by genetically diverse pollen.
“Diverse”, in this case, implies that the genetic diversity is recognizable. It would not help much to add morning glory pollen when pollinating a rose. But when making remote crosses, some more familiar pollen (from a closer relative) may encourage the seed parent to feed the fruit more than it would if only the remote pollen were used.
An example of this was shown by Mangelsdorf & Reeves: Maize-Tripsacum hybrids (1931), Figure 4
“Some ears set seed almost 100 per cent. The hybrid seeds, however, are very small compared to maize seeds of the same age. A few maize seed near the middle resulted from pollinating with maize 24 hours after pollinating with Tripsacum. Note that some of the hybrid seeds adjacent to the maize seeds are larger than their sibs.”
Apparently, the larger hybrid seeds came about when both maize and Tripsacum pollen tubes grew down the same silks. The seed parent recognized the maize pollen tubes and nourished the seeds as if they were “pure” maize, even though the Tripsacum pollen tubes fused with the ova.
Karl
This whole thread is fantastic, most is past my understanding, but I am trying, I am disecting words that I do not understand then the posts make more sense to me.
Karl, as I am very new here some of my questions are “out there”, if you have time could you give some roses(relatives) that might do this.
There are 3 threads here all intermingling into my ‘quest for yellow’, Thanks to all
David,
Here are a few references for species in the Rosaceae:
Yenikeyev: Pollination with a pollen mixture (1965)
Hybridization of the blackthorn (Prunus spinosa L.) with the domestic plum (P. domestica L.) was also facilitated by using a pollen mixture of several plum varieties (cf. also YENIKEYEV, 1960, 1962). It can be seen from Table I that the percentage fruit set resulting from pollination of the blackthorn with a pollen mixture of three plum varieties, was much higher than that obtained after pollination with each variety separately.
Genetics Today: Proceedings of the XI International Congress of Genetics (1963) p. 213
13.13. Pollination with Pollen Mixture to Produce Interspecific Hybrids of Plum and Cherry (Prunus),
K. K. Enikeyev (Moscow, U.S.S.R.).
As a result of pollinating Cerasus Besseyi Bail. with pollen mixture of several European varieties of apricot (Armeniaca vulgaris L.) quite viable and fertile hybrids have been produced.
Euphytica 29 (1980) 385-390
Pollen and Pollination Experiments. II. The influence of the first pollination on the effectiveness of the second one in apple
T. Visser and J. J. Verhaegh
It was found earlier that repeated pollination by hand or by bees increased fruit and/or seed set of apple, pear and plum (KONDRAT’EF et a!., 1972; PANOV & PETKOV, 1975). Our data confirm this with respect to apple. It appeared that pollinating twice at an interval of one or two days, on average doubled the seed set per pollinated flower as compared with pollinating once (Table 1). As normally fruits with sufficient seeds only are retained on the tree, it is understandable that a second pollination would improve fruit set by adding to the number of fertilized egg cells of the flower. However, a new element of the present study is that, with the aid of ‘marker pollen’, the second pollen was shown to be on average twice as effective as the pollen applied first (Table 4). That is to say, against every three seeds formed by a single pollination, a double one produced six seeds, of which two resulted from the first and four from the second pollen. Hence, the second pollen, besides fertilizing extra egg cells, contributed to seed set by partly outmanoeuvring the first pollen (for 1 in 3 egg cells, see also Table 5).
Soviet Plant Physiology pp. 190-193 (1958)
Sedov: The effect of the variety of the pollinators and of pollen mixtures on various physiological processes in apple seedlings
The higher degree of hydration in apple seedlings obtained from seeds resulting from pollination with mixtures of pollen, and also the increased rate of photosynthesis in these seedlings indicates their high vitality. Proceeding from this we should also note that it is necessary to have 2-3 varieties of pollinators in the maternal seed plantings of apple together with pairs of the main variety suitable for that place; this guarantees pollination with a mixture of pollens under natural conditions in each instance, and significantly increases not only the percentage of fruits set, but also guarantees getting vital pairs of seedlings. It is also necessary to expand the use of mixtures of pollen in selective breeding since more vital hybrids are produced as the result.
Karl