I have a couple very basic question about variegated citrus-- what causes the variegated foilage in citrus? (I am not talking about the disease CVC or citrus variegated chlorosis) Are seeds of variegated citrus "true to type"? Can new variegated varieties arise from a seed? I have read that they are chimeras and can originate from grafting-- is that true? Skeet
i just got 2 piecesof scion wood from a variegated pink lemon and they have been growing for several months so will be a while till i get to plant any seeds from the two plants that are now growing. the little bit i know about variegated plants is that allot of them are mutations/sports on an existing plants. some say it is from a disease some from radiation or from chemicals i did have one hibiscus throw a variegated piece but it was unstable and went away. not sure what caused it. i know some plants where a seed was planted from a variegated plant the seedlings will be albino no green at all not sure about citrus if they may be variegated from seed or not. know very little about graft chimera accept allot of the time they are not stable enough to keep the chimera caracteristics they usually revert one way or the other.and thats just from the limited info about them that i have seen.the only species i have grafted in hopes of a graft chimera is datura onto brugmansia. should be really different looking if one does happen. and also not sure of the percentage of chimera that are variegated. sometimes they just look different than both rootstock and scion and are not variegated. hopefully someone will come along who knows more about all this. its interesting just wish i knew more about it. hope any of my ramblings helped
I have found out that at least some varigation is caused by a virus, just not the CVC virus. It is an interesting question. I had a varigated seedling, but it did not make it through the winter. Skeet
Are seeds of variegated citrus "true to type"? The seeds may be true to type for being a Lemon from the fruit which they came from but most variegated seedlings will green out or return to green as seedlings as time goes by. Can new variegated varieties arise from a seed? Yes, there have been some varieties that came about as seed gathered from a fruit but usually these are fruit that had a sectional chimera as a result of a branch sport. Then again I have a sectional chimera right now on a Sanguinelli Blood Orange that did not arise from a branch sport. I will save the seeds and give them to a nurseryman to grow on but I'd prefer to have had some variegation showing in the leaves as well. Even when we bud a variegated scion onto a variegated rootstock the number of seedlings that will be and remain variegated is a small percentage. (It was this finding is what dispelled the sky is falling notion that manipulation of the color virus that causes variegation in Camellias would automatically infect all non variegated forms, thus ruining them). That does take the fun away but if the mutated or color enhanced gene is present in both the rootstock parent and the scion parent then the frequency of which we will see seedling offspring be variegated is significantly higher (the numbers that remain variegated later on is not as significant) than if we were to take seed from fruit gathered from a variegated scion that was budded or grafted onto a green seedling. I have read that they are chimeras and can originate from grafting-- is that true? Whip grafting has been known to help induce a so-called chimera or in this case a branch sport due to the incompatibility of the two woods. We can and have seen cleft graft incompatibilities live for upwards of ten years and longer in Magnolias and in some infrequent cases in Japanese Maples and Dogwoods as well, usually Cornus florida. We can get an unusual growth emanate from the two woods that is genetically neither that of the branch parent, nor the bud wood parent. At the time of mitosis the genes are doubled and we may even get a new shoot growth that is tetraploid. This result is the branch chimera and people have taken wood from that growth and budded it onto another plant. Some of the variegated forms were perpetuated in this same manner. Most variegated forms came about as a branch sport that appeared to be variegated. Some held true over time when budded onto green rootstock and were grown on but most returned back to green later. The better way to ensure that the variegation stays is to take wood from the variegated branch sport and root cuttings (Oranges, Mandarins) and select out the rooted cuttings that stay variegated from them or do whip grafts of the variegated branch sports (Lemons, Limes, Calamondin) and then continue the cycle of taking wood that grows from the whip graft and use it as our budwood to t-bud onto a known green rootstock. Today people take the variegated budwood and bud directly onto a green rootstock rather than fooling around with rooted cuttings but for some forms of Citrus it is better to have both the variegated rooted cuttings used as a rootstock and then bud the variegated wood onto it. This is what the next step would have been for the variegated Cara Cara Navel Orange but it did not get that far along. Thus some people had to be satisfied with having the rooted cuttings if they had them instead and some of those cuttings later returned to green a few years later as was predicted based on the Camellia trials. There is more than one virus, either in the soil or is insect transmitted, that can cause a variegation in the leaves as well as on the rind of the fruit of some Citrus. Seeds gathered and germinated from the speckled fruit have usually yielded offspring that do not live long. We can see the variegation in the first few leaves and then wham, the seedling dies. This type of viral activity lessons the vigor in the plant. What happens when an Orange gets hit by Tristeza, it weakens and gets overcome by the infecting virus in its system. We see the same type thing in seedlings that show some variegation in a leaf or two and then the juvenile leaf falters and the rest of the plant probably will cease to function rather soon also. Jim
Very Interesting Jim, Has anyone tried to compare the DNA of the variegated part with the non variegated part of a plant? This reminds me of the question of where the node count information resides in a citrus plant. Skeet
I would prefer tests done on chromosomal DNA as my foundation as opposed to chloroplast DNA, of which the latter has been conducted on Citrus. Years ago there was a Variegated Eureka. What would be interesting to know is how that plant differs from the standard Eureka, if we can find an old plant on its own roots, a seedless Eureka and the Variegated Pink Eureka. This reminds me of the question of where the node count information resides in a citrus plant. I believe Dr. Manners in the Citrus Growers Forum may be able to offer some more insight here. Personally I feel the node count and node elongation is more applicable to Grapefruit, Pomelo and Pummelo seedlings than it is to grafted or budded forms of them. I believe an example used in the past and I agree with this is that node count and node elongation becomes important for seedling Avocados and seedling Grapefruit to bear fruit. On the other hand there have been 3 foot tall grafted Avocados and 3 foot tall budded Grapefruit with fruit on them which gives and tells of another perspective. I do believe the age of the wood used as the scion comes into play for the mini Mexicola Avocado that I had years ago to bear fruit at such a young age and such a small sized tree. Have not owned a "super dwarf" Grapefruit but I have seen it. Jim
Jim is correct. Obtaining the required node count before a citrus tree matures, ONLY pertains to seedling trees. A grafted citrus tree is mature from the first leaf, by the very fact that a mature bud was removed from a producing tree, and implanted onto the new rootstock. The grafted bud "remembers" that it is a mature bud, and "remembers" its mature node count number. All that is required is for the new scion to obtain a little height. - Millet
..............This reminds me of the question of where the node count information resides in a citrus plant................ Probably resides on the trees DNA chain. - Millet
Skeeter asks the question....." what causes the variegated foliage"....... Plastids which are in the tree's leaf contain genes that contribute to the development of the chloroplasts (the green color in leaves). These genes are passed from generation to generation by duplication and division of the plastids (their inheritance is distinct from that of nuclear genes). Since egg cells contribute plastids to the zygote while pollen cells usually do not, only the maternal parent has a part to play in plastid inheritance. Effects on the chloroplast genes are especially noted in the inheritance of variegated color patterns in the leaves of the tree. Here the egg cell contains both normal plastids and plastids that cannot develop into green chloroplasts because of defective genes. Some cells in the embryo have only the defective plastids. These cells divide further to produce the distinctive white or yellow patches on the leaves and stem of a variegated tree. - Millet
Thanks Millet, that is the first time I have heard that explanation and it helps to understand the biology. As for the node count question, I was telling my wife about the node count requirement for seedlings and she asked me and interesting question-- How do the various limbs on the tree communicate "the node count" or does each limb have to reach the required node count separately? Skeet
my limited understanding is that node count has to do with, when the plant decides its an adult and goes thru hormonal changes telling it to start flowering and fruiting. when a bud or scion is taken off of the plant it still knows its an adult it just may take a few years to get big enough for the plant hormones to build up to a point of making it flower and fruit. and i may be way off track but again thats my limited understanding.
You start with the seed as node zero, and count up from there. When the plant makes its first side branch, say at node 14, the next node above that on the main trunk will be 15, AND the first node on the new side branch will ALSO be 15. So on a big old tree, there may be hundreds of node 4762. Each node "knows" and "remembers" its own number. If you bud/graft node 4762 into the base of a rootstock seedling, you don't change the seedling's node count at all, but when the scion grows out, it makes 4763, 4764, etc. on the scion stem. The result of all this is that a seedling must grow rather far away from the seed to flower, hence the problem with flowering a seedling in the house. If you prune it back, you remove some node numbers. If you pruned to #43, throwing away nodes up to 100, when the house tree resumes growth, it resumes at 44, NOT 101. So a constantly pruned house tree may never flower. And even an ancient seedling tree which has been flowering and bearing fruit for 100 years, if cut down and the stump resprouts, it will be juvenile again. The nodes never forget their numbers. But this is also why the technique of air layering or rooting a cutting from the top of a seedling house tree, and replacing the original plant with the new propagation is a good way to get flowers and fruit, eventually. If you take a cutting that contains nodes 56, 57, 58, and 59, root it, and make a new potted plant of it, it will resume growth at 60. So you've done away with several feet of stem length in the process of getting to the minimum needed node number for flowering. (coppied from a response to Millet from Malcolm Manners ) - Millet
Millet, Thank you, thank you, thank you for that information. I was actually going to ask that question myself. My 5 lemon trees are getting tall (2 are about 6 foot) and I will probably be moving in the next few months. I was not happy about moving tall trees possibly in cold weather. I will start air layering now and hopefully will have new rooted, much smaller trees when the big day comes. I so appreciate all your knowledge and willingness to share. Thanks again. Sabagal
I have grown a bunch of etrong lemons and one is totally white and growing very well strange....does anyone know if this is a new species if it survives.
