2/21/13

E-mail – Wrinkled LEAVES


Doc,
I just started 20 or so seedlings. They are two weeks old with one set of leaves The leaves are wrinkled and the plants are not growing. I am using a T-5HO and I have it about 2 inches above the plants and its been on 24/7. I watered the plants with tap water, then during the second week I used a high phosphorus fertilizer with lower N and K. Please help.

Hello. You did not say what medium you are growing in. If you are using new soil, then most likely it is not a deficiency. Also, you should use a 25-50% diluted fertilizer for seedlings. But since you said you first used tap water, I doubt you already have a nutrient overload. I think maybe you have the light too close. The HO stands for high output, believe it or not, plants can get too much light. Good growers know that most things in Biology involve the Goldilocks principal, not too much, not too little, but just the right amount is what you need. (Click here to read my post on the right height for your light). You should try to raise the light to about 6-8 inches above the tops of the plants. You should notice growing. Growers using LED should also beware of having too much light.
One thing you could try to quickly see if it is overload (stress) from light is turn off the light for six hours. If you raise the light and put the plants on 18/6 for a couple days you should see growth. You can then switch back to 24/7 for as long as you usually do in your grow cycle. If this does not help, send me another E-mail.

Good Growing,
Dr. E.R. Myers

2/14/13

Colchicine and Polyploid Breeding


This post is a follow up to a post on colchicine use. If you have 100 seedlings and apply chemicals like colchicine or dinitroanilines to induce polyploidy, you could get a single super spectacular specimen of plant that grows faster, yields more and is over all more vibrant. However, why does not everyone do this? Maybe it is hard to get colchicine? The only use I found it for is treatment for gout. I have read colchicine is toxic so that alone may be a reason not to use it. I have not found any studies examining if it can be metabolized by plants. What this means is if plants cannot break it down, colchicine will remain in the plants, similar to how heavy metals can remain in the body for long periods of time. This means if you consume the plant, you may consume colchicine too.

Acquiring colchicine and potential health risks aside, the first thing one could expect is to lose 50% of the seedlings minimum. That is 50% of your money for seeds down the tubes before you get started. It might be possible to take several clones and try it on established clones if you pay a lot for seeds. Several changes in the plant result from induced polyploidy. These changes are due to changes in the genetic composition. Some (not all) of these changes will result in bigger, better plants. In general, polyploidy results in increased leaf and flower size (which can be seen in increased cell size and chloroplast count). These changes are sometimes referred to as the gigas effect. This gigas effect has found application in the breeding of medicinal herbs in the production of pharmaceuticals. Hybrid vigor resulting from interspecific crosses in allopolyploids is one of the most common ways crops are being improved today. These genetic traits/changes will not always remain in later generations. Once plants become polyploids, they begin to undergo changes to make their chromosomes more like pairs of chromosomes. This is called diploidization. There are a lot of reasons plants do this one reason might be to lead to increased fertility

It seems that how one gets a super spectacular specimen of plant, is not just soak seeds in magic juice. Many plants like strawberry and blueberry have naturally occurring polyploids, and these plants are then bred for specific traits. (read this post on plant breeding) As I wrote on the polyploid post, the benefits of polyploidy is not from doubling the chromosomes. Ferns for example often have 100-200 chromosomes whereas corn has 20. The number is not important; it is the GENES on the chromosomes that matter.
So, if you have gene A that gives big flowers, (or any trait you want) you could have a triploid with three copies (AAA) or tetraploid with four (AAAA) instead of the normal diploid AA. The more A genes a plant has, the bigger its flowers. Most likely there is a limit to how much improved growth you get with just more A’s. Today, most crop polyploids have a mixture of genes for flowering (or other traits). When you have two different genes that increasing flowers say A and B the two genes in multiple copies give a synergistic effect compared to just a percentage of increase you get from adding more the same gene. In other words having AABB is better than AAAA or BBBB. To combine different genes like AABB, you get the A and the B together by breeding. Just like F1 hybrids are awesome b/c they have great genes from two parents, Polyploids are usually found to be better with combinations of good genes for a trait. The term for this improved growth due to a mixture of genes is heterosis
Most experts take years to get a single super spectacular specimen this way. Is it possible? Yes. Is it easy and cheap? No. I wanted to let the readers know it is possible, but there is A LOT of complicated stuff involved. I am pretty sure you just can’t soak seeds of a crop and get some super freaks. But then again, that is why science is needed, to prove things. If anyone has any first-hand experience, please E-mail me or leave a comment
Good Growing,
Dr E.R. Myers

2/7/13

Colchicine and Its Effect On Plant Growth

Polyploidy, in some crop plants occurs naturally but it has been induced by treating plants with chemicals, such as colchicine. 
Using ColchicineDO NOT SOAK THE SEEDS! When seeds are soaked in colchicine, most or all fail to reach maturity due to colchicine’s retarding property on root growth. Soaking seeds was what was done in the 1930’s, with little success. Colchicine use is increasing in scientific literature and I will cite specific studies in this post for readers to follow up on if interested. One thing recent studies have in common is that all applied colchicine on SEEDLINGS, not seeds. Soaking the seeds is like trying to reinvent the wheel. colchicine inhibits root growth, so what most people have done is applied it when seedlings are 4-6 days old.  The colchicine applied on the very tip of the plant (the apical meristem where growth is occurring), as far away from the roots as you can get. This can be done with an eye dropper or you can use a cotton swab. Experimentation is still going on (No one yet knows the best amount to use) so use the scientific method and give plants different amounts/concentrations. You can try mixing a 0.5mg tablet with 50ml, 100ml and 150ml of water. Of course you can try  weaker and stronger strengths. The important thing is to keep accurate records. In the few studies I read, they applied the colchicine at 12, 24 and 48 hrs but this also can be varied.   Even doing this, you will get a lot of mutated seedlings, but some will become polyploid. Also, temperature seemed to be important. Warmer temperatures lead to more mortality. In orchids, when young seedlings are treated in liquid culture with 50 mg/l colchicine, about 50% of the seedlings develop into tetraploids (polyploids with 4 copies of chromosomes). Moreover, when working with a maple tree, Liu et.al. (in Euphytica Volume 157, Issue 1-2 , pp 145-154) had better seedling polyploid production from soaking the seeds (40%), but all the seedlings died due to poor root growth formation.  Many studies just looked at polyploidy, they did not see if the plants could actually mature which is why people keep trying colchicine by soaking seeds.  Liu et al. also applied colchicine to the tips of growing seedlings and a few did become polyploid, and did survive to maturity. So, colchicine is not a magic bullet.
Why use Colchicine - Polyloid plants usually have increased growth, meaning they grow faster, yield more and have many improved or novel traits. (Click here to read more about what polyploid creation can do for plants)  We can look at orchids for examples. Orchids have been breed for a tremendous variety of flower colors, shapes and size. One way to get unique combinations of these characteristics is by creating polyploids. Soaking the seeds in colchicine has been done since the 1930’s. However, when the seeds are soaked many plants do not survive to maturity, many more of the plants are a chimera, meaning only parts are polyploid, some show aneuploidy and other parts have the normal cell number. It was not until the 1980’s when consistent ways to create polyploids were developed. If you are interested in reading the scientific literature check out, Plant Cell, Tissue and Organ Culture 1981, Volume 1, Issue 1, pp 103-107, and their citations.

Keep in mind, even if you do get polyploids, when you have plants with more than the normal number of chromosomes they are not guaranteed to be ‘better’. The benefit comes from having more genes (which are pieces of DNA located on the chromosomes) that make the plant grow well. For example, the normal number of chromosomes is two, one from dad and one from mom. Now, say gene A makes large flowers. If you have a triploid plant, it can have AAA or three copies of that gene. This means the plant will have 1/3 or larger flowers than a normal AA plant. However, it is also possible for the plant to have three genes that make small flowers. Again, the benefit from polyploidy is not in the number of chromosomes, but in the combination of genes, just like F1 hyrbrids usually show a hybrid vigor, this is what you get with polyploidy, (it is termed heterosis). If you have more chromosomes, and you START with two good parents genetically, you should be able to get a good combination of genes in the offspring. Polyploid offspring have more chromosomes so a greater chance of having more combinations of good genes.

A caveat, polyploid plants can result in difficulty breeding/getting offspring. Once you have a created a polyploid plant, you may need to clone the plant to get new plants. A polyploid plant will have many gametes that have the incorrect chromosome number. This abnormal chromosome number, from colchicine has been used to create "seedless" fruit, such as seedless watermelons (Citrullus lanatus). Seeds are babies if you will, so by creating sterile polyploids, they will produce fruit, but not seeds. If you want seeds from your polyploid, you will have to try many times and be lucky.

I have read that colchicine's is toxic, and regulated by the FDA, I don’t know how to get it, or if you should. I have also read it is used to treat gout in humans.  Breeders that use colchicine grow hundreds of plants, because many will be deformed and/or grow poorly if at all. I would not recommend it for the hobby enthusiasts, and I don’t like to use such powerful chemicals on plants I consume.  I will look into how long colchicine stays in plants and other long term effects of colchicine in later posts...

Good Growing,
Dr. E.R. Myers

2/2/13

Polyploidy


HAPPY GROUNDHOG DAY!

I am writing this post as background information before I answer a question from Mike at the HTGSupply.com Lansing MI store. A customer asked about colchicine and plant growth. Colchicine is usually used to induce (make) polyploidy plants.  This is done by doubling the number of chromosomes. I have read that Oryzalin also will double the existing chromosome content.

Polyploidy refers to a numerical change in a whole set of chromosomes, meaning you have 3,4 or even up to 12 copies of all the chromosomes. In high school Biology you should have learned two is the ‘normal’ number of chromosomes for most living things. A similar sounding term, aneuploidy is when only a few or parts of chromosomes are present in more than two copies. In humans Down syndrome is caused when individuals have an extra (three total) copy of chromosome 21.

Polyploid organisms have more than two paired sets of all chromosomes. As I said, most living things are diploid, meaning they have two sets of chromosomes. In humans (Since we can easily understand our own reproduction) the pair of chromosomes resulted because one set came from your dad (sperm), and the other from your mom (egg). A polyploid organism would get 2 from either or both parents increasing the number of all chromosomes. Polyploidy occurs in some ‘lower’ animals. It is very rare in mammals but is not uncommon in plants. I have read estimates suggesting 30–80% of living plant species are polyploid. The larger estimate comes from studies showing evidence of ancient polyploidy (paleopolyploidy). For example, corn has 12 chromosomes. But genetic testing suggests that corn does not have two copies of six (12) but really has four copies of 3 (12) of chromosomes.

Polyploidy sometimes occurs in localized tissues of plants due to abnormal cell division. However, it is much more important, biologically speaking when it occurs throughout the whole plant
Polyploid plants arise spontaneously in nature. Polyploidy can also be induced in plants by adding colchicine, oryzalin or other chemicals to seeds. The effects are not well documented and each chemical will most likely have different outcomes.
Most polyploids display heterosis compared to their parental species, and also often display unique growth habits. Heterosis means hybrid vigor. Plant breeders have know for centuries that when you cross two pure breed plants with different traits, their offspring show increased growth and overall vigor. You can see the benefits in the number of crop that are polyploids: Strawberries, sugar cane, blueberries, apple, banana, tobacco, peanut, watermelon, cherry, canola, wheat, cotton, potato and many other plants like orchids are polyploids.
There are two types of polyploids, autopolyploids and allopolyploids. Autopolyploids occur when the chromosomes are from the same species, this is common in potato for example. Allopolyploids occur when the chromosomes are from different species. Polyploids do not always have predictable features, they usually grow larger and faster, but bamboo for example has mostly increased vegetative growth, other plants have only increased seed set etc. It is in the breeding of polyploids that we select the traits that are most beneficial.

Click here to read more about what creating polyploids can do.

Good Growing,
Dr. E.R. Myers