Pollination basics to advanced....Pollen storage tools/grafting tools

[Inyan]

Mentor pollination, teacher pollen, or pioneer pollenation is the use of a small amount of pollen that is highly compatible with the seed parent mixed with a large amount of pollen from the intended pollen parent. Variations to this process exist. One variation is allowing the least compatible pollen to sit on the stigma for a few hours to even an entire day to give it a head start. Those few pollen grains that are able to pollinate those very few ovules will do so. The seed pod would likely abort however if the next step of placing viable highly compatible pollen was not done within a few hours to a few days later depending on the species. Still other methods of hybrid stimulation from mentor pollen can be had with pollen that is compatible but inactivated by radiation, heat, methanol treatments, etc. My understanding of this process and how that variation works is that the stigma itself may present a barrier to hybridization until a compatible pollen is recognized. The dead compatible pollen provides the stigma with a recognized compatible source signaling it to accept the pollen. The least compatible may now be accepted by the stigma as the stigma becomes chemically receptive to pollination and or produces hormones that stimulate the pollen to germinate. 2n gametes can also occur in some ovules in a diploid plants/cacti but may do so in such low numbers that a seed pod would likely abort without the mentor pollen. What this means is if a cacti/plant has a triploid block to hybridization, that this can be overcome with mentor pollen producing tetraploid offspring via this rare occurrence of 2n ovules. The trick however is how to discern if you have a hybrid? If obvious differences or blending of traits are seen then you have your answer. However, you may need to make additional crosses to determine if you have a cross if the two are so closely related that the phenotypes fall within the normal range of one or the other or one plant/cacti has dominant traits over the other. However, it gets more interesting as novel phenotypes can also occur due to new enzymes and shuffling of the genotypes that would never occur otherwise. Such is the case with Brugmansia aurea x Brugmansia versicolor... a rare few show a new phenotype which is the source of the double flowered Brugmansia we see today. What is more interesting, as is the case with Brugmansia... these rare phenotypes sometimes only occurring in 1 of a 1000 seeds presents this new phenotype as a stabilizing phenotype... meaning a double to a double will give you more doubles. To further understand why some crosses fail to present with seeds... it is as simple as that plant or cacti needing a certain number of viable seeds to mature or the pod aborts. This can vary from plant to plant. With the addition of just enough mentor pollen to facilitate a successful seedpods retention, the pollen that normally would not take is now afforded the possibility of growing out those few rare hybrid seeds. Still, you may have the few hybrid seeds abort at an early stage and this can be seen in Brugmansia arborea x Brugmansia aurea type crosses utilizing mentor pollen where a very few hybrid seeds form full seed coats, but only partially developed embryos are found inside. The vast majority of the ovules remain unfertilized small black dust like particles on the inside of the pod with such crosses in the Brugmansia genus. The picture presented is a picture of an aborted embryo inside a fully developed seed pod. The cross was indeed one that should not have been possible. My point in sharing this picture with you is to let you know that yes, impossible crosses can sometimes be made with these techniques, but embryo rescue may be needed if you are to move forward. Other crosses that may be possible, but result in an aborted fruit before the seed can mature is also possible, but with those crosses the fruit aborting early can be thwarted with the simple addition of the right percentage of mentor pollen to enable the pod to survive. This has to be experimented with to determine approximate ratios and or timing of pollinations and if one has done it right... there should be a high percentage of aborted ovules, a few non-hybrid, and a very few hybrid seeds. Again, there are many variations to this technique, but it can and does work.

[Chief BigTittyFlapFlaps]

if you had asked me i would have guessed that was a booger.  honestly though, I'm having trouble visualizing this concept.  i think my poor understanding of plant physiology is holding me back.  ..i thought that once the pollen connected with the stigma that was it.  pollination had occurred.  i didn't realized the chemical pathways involved multiple steps.  although after some consideration it seems self evident.  i'm trying to think of how i could apply these techniques to lophophora?   

[Inyan]

"L.Williamsii has been successfully fertilized by Ariocarpus Fissuratus, L.Diffusa, Mammillaria Bocasana, M.Zeilmanniana, Strombcactus Disciformis, Turbinicarpus Pseudomacrochele, Astrophytum Asterias, and Epithelantha Micromeris." http://www.magicactus.com/description.html'
What you don't see here is how the cross was made and I don't claim to know how each hybridizer made their crosses. You also don't see whether a southern or northern location variety of Lophophora was used for the successful crosses. Perhaps, it was a hybrid between different location or regional varieties. The point I'm trying to make is there is a difference in that pollen phenotype variations as well as fertility... self-fertile or self-incompatible makes another difference that cannot be overlooked. The differences in pollen phenotypes with the southern form having 0-6 apertures and the northern population having 0-18 apertures makes a physical difference that one can see along with different shapes. All of this aside, you can't rule out a cross as impossible unless you have exhausted several attempts using various methods and techniques and then the cross is only highly improbably using the techniques you have used. There is always a way to breed two different cacti together even if you have to resort to creating a tetraploid, reducing ploidy via anther culture, embryo rescue, or protoplast fusion. The problem for the average hybridizer is that these techniques require more and more expertise, equipment, etc. and most serious hybridizers never move past the point of working with mentor pollen or increasing ploidy in their flowers, seeds, scapes, pups, etc.
As for your question, with absolutely no expertise you can understand that a stigma allows a particular pollen grain to develop and grow down to its ovules through enzymatic compatibility and other mechanisms as I understand it and I don't understand it in its fullest. Once there, it has to be understood that there are differences in chromosome numbers that rarely occur in pollen as well as ovules. There are probably more differences than many yet know or understand as research continues to be done in this area. The idea behind pollinating with a least compatible pollen first is to allow a large quantity of pollen from a pollen donor that should not normally be able to induce a mature seed pod to begin to form a few seeds... perhaps just one as there may only be one ovule that is different enough genetically to accept that pollen. Now, with many plants/cacti that one seed may not be enough to trigger a fully developed seed pod and it will normally abort that pod. The trick is to give this incompatible pollen ahead start. Some use a mixture of incompatible pollen and dead compatible pollen first to chemically trick the stigma into accepting the foreign pollen or least compatible pollen as well, but that trick is not always needed unless the stigma surface itself is blocking the pollen from growing by some means be it chemical inhibitors or simply not providing growth hormones for the pollen. After a few  hours of incompatible pollen placement mixed with dead compatible pollen or not... a diluted compatible pollen can then be added in sufficient quantity to enable a seed pod to form and not abort. If done to excess you may find that you have very few ovules that have not germinated and then you must grow out all those seeds long enough to determine if you have any phenotypic differences that clearly show markers of the two different cacti you have crossed. Many times, if done properly... you will find that many ovules remain unfertilized with just a bare minimal number of seeds... just enough to ensure the seedpods survival will be in your pod. That part is subjective as you may be fine with growing out as many seeds as possible and later determining which ones are hybrids. Second, you have to be aware that rare phenotypic combinations can occur and may take a thousand seeds to see. This means you may have to pollinate a 1000 flowers to acquire a single seed each time to see something truly special or unique. Not that your other 999 hybrids aren't unique and special, they may show a blending of traits, but perhaps nothing new to both. You have to account for the fact that one cultivar, species, etc. traits may be dominant to the other that one is working with. This means, you may have to take all of those seeds from your cross and make the same cross with the same techniques again to see some real progress. Some of your crosses may be so unrelated or incompatible that at best you are getting aborted seeds within those fully formed seed pods. This is where it gets weird, I've seen someone create a B. arborea x B. aurea group hybrid without any of these methods... pollen grains vary! Ovules vary! So, for many... if the cross is desired and you have the pollen... never give up as an excess of pollen from one genus, species, etc. can always be used to dilute your desired crosses if you also don't mind the hybrid possibility however unlikely it may be. Who knows, perhaps after your first few thousand crosses with Lophophora pollen diluted with Trichocereus pollen you will get that one in a millionth hybrid without trying. Another interesting thought... pollen grains vary and some may grow faster than others. If your pollen is not diluted you are not going to have a chance for each and every pollen grain to fertilize an ovule. You are not getting the full genetic potential possible from that pollen.
The long and short of it is that most hybridizers over pollinate in the beginning and lose the genetic diversity that each grain of pollen represents. By mixing pollen and creating diluted pollen cocktails you run the risk of having unexpected, but hoped for crosses to appear. You have to keep an eye out for the possibilities that this may open up for you. You have to keep records of what pollens were mixed into your cocktails and how you diluted the pollen so you can approximate those experiments later if you are successful whether it was intended or not. I look at pollen cocktails as playing the lottery. You may get lucky, but you don't count on them getting lucky until you have reason to believe you have something truly unique. Then, you may have to work with those unique rare genetic phenotypes that arise to see where they may lead you.
One of my personal recipes for success.
I place pollen of incompatible or less compatible pollen first. I wait an hour to a full day depending on longevity of flower. I then use dead compatible pollen mixed with incompatible or less compatible pollen and make another application of pollen. I then wait another hour to a full day depending on longevity of flower. Lastly, I apply a pollen cocktail with viable compatible pollen in minimum quantities needed to ensure a seed pod. The last pollen cocktail is made with serial dilutions with least compatible pollen still forming the majority of the pollen in the mix. These dilutions are further diluted with fine powdered sugar.

[Chief BigTittyFlapFlaps]

Ok, that makes sense now. thank you very much for clarifying.  I'm feeling a little slow right now... These are new concepts for me.   I can now see there are a number of ways this can be applied.  I'm glad you're posting this stuff because I will need to reference it when the time is right.  I already need to re read the section on dilution.  I think some of my confusion was not realizing that seed pods can be aborted if not enough of the ovules are fertilized. 

[Inyan]

I've talked to many hybridizers and read a fair amount of literature on the subject of pollination and I don't pretend to understand it all either. Rather, I try to glean from it why it works and how to make it work better. As long as I get some results in the end that is all that really matters. You don't need to fully understand the mechanics of how a car to know how to drive it.

[Inyan]

And one more reason I want to see more Trichocereus hybrids... these can all hybridize with Trichocereus....

[Chief BigTittyFlapFlaps]

YEAH RIGHT!  that first flower on a trichocereus would be so rad!  what are the names of those plants? 

[Inyan]

These are all multihybrids to my knowledge. Their names are listed under their picture. And yes, from what I can tell looking at all the Acanthocalycium, Chamaecereus, Helianthocereus ,Hildewintera, Lobivia, Psuedolobivia, Soehrensia,  multihybrids, etc.... there is a lot that can be done. I've been eyeballing several hybridizers in Europe and a few others as well that have managed to create dinner plate sized flowers, fragrant flowers, tricolored flowers, etc. with multihybrids and to say the least... I've jumped on that band wagon with several well known hybrids.... and still on the look out for some rarer genetics to add to the mix.

[Inyan]

Super Apricot x this next hybrid.... I'm thinking fringe and fangs....

[Chief BigTittyFlapFlaps]

oh jeez.  i see the names now... i imagine many people would pay big bucks for a colourfully flowered trichocereus variety that retained its fragrance and medicinal qualities. 

[Inyan]

I agree... and these are not even the tip of the iceberg of what it is possible to create as there are some very interesting and extremely rare hybrids out there that I will not even mention as of yet as they are burning a very deep impression in my mind of the possibilities I wish to create. Suffice it to say that there are many more possibilities out there than I am relating in here. Those that truly wish to create these beautiful marvels are going to have to do a little leg work and create them on their own as I have yet to see a source for the hybrids I intend on making... I won't spoon feed it all just yet, but if you look carefully at some Echinopsis multihybrid flowers you can see some influence that just should not be there.

On another note, I found a good article on storing cacti pollen specifically. I've summarized it below.
In one study, cacti pollen lost its viability within one day of storage at room temperature or just a few days in the refrigerator. To me, this means shipping pollen is not going to work if kept at room temperature or above and no other means of preservation is done.  Oven drying of pollen at 70 degrees C for 30 minutes helped reduce moisture content to acceptable levels of moisture content regardless of initial moisture content of pollen. The stigma itself often produces enough moisture to rehydrate pollen. Increasing the humidity may be of benefit. Starch was found to increase germination rates and pollen tube growth. This is another reason why hybridizers frequently use flour or cornstarch to dilute pollen. Other reasons for diluting pollen are to simply make your pollen go further as many beginning hybridizers use far more pollen than is needed for fruit set.  Pollen dried and stored at subfreezing temperatures in this study gave 100% fruit set after more than 9 months storage. Dried pollen stored at normal refrigerator temps of 4 degrees C. yielded only 60% fruit set after the same period of time and smaller fruits and lower seed counts.
I've had good luck with simply air drying pollen for a few hours and placing pollen inside an airproof container with rice or salt. The bottom line of all of this is that the drier and colder you can store your pollen the better. Flour or cornstarch may help with pollen germination and growth as can increasing the humidity around your flower after pollination. Pollen properly dried is still viable for 9 months properly stored in the refrigerator this way, but seed set will be lower. Placing that same pollen in the home freezer and stored the same way increases seed set and acceptable levels of seed set are still seen 9 months later. Pollen stored in the refrigerator properly dried can still yield fruit 9 months later with a cacti pollen that is normally only viable for one day at room temperature. Anything you can do to increase the seed set such as removing from the refrigerator and placing in your home freezer should be done if your serious in your efforts to produce seed of a hybrid origin.
http://hortsci.ashspublications.org/content/35/1/22.full.pdf