Leucoplasts and variegation

From: "Steve Lucas/Exotic Rainforest.com" <Steve at ExoticRainforest.com> on 2010.12.28 at 22:44:00(21698) I have been following an internet discussion on variegation and have run into some terminology that at least appears strange. As I understand the discussion the term leucoplast is being used to possibly describe leaf variegation in Spathiphyllum. I was totally unfamiliar with the term so I ran it through my database of some 200 PDF aroid books and articles and not a single return was hit. I then pulled every botanical dictionary off my shelves and read the definition in each. Several listed nothing. For those like me that have no idea what the term means, I have compiled this definition from all my botanical dictionaries as well as a few on-line internet articles. If it is wrong, I would appreciate being corrected by some of our scientists: "Leucoplasts are a category of non pigmented plastids or organelles found in plant cells. An organelle is a specialized subunit within a cell that has a specified function. These colorless plastids are found in the cells of roots and the underground storage organs including underground stems such as tubers, bulbs and corms. The are involved in the storage functions of these organs including the storage of foods such as starches, lipids and proteins however some have no involvement at all in the storage process but instead process fatty acids as well as amino acids. Typically leucoplasts are much smaller than chloroplasts and have no involvement in the leaves of plants." Is the term leucoplast ever applicable to aroids? For those still not clear it just means the lack of green cells. I realize that variegation is a natural process but it has been artificially induced in tissue culture as a result of economic reasons. People will often pay more for a variegated plant! As I understand from previous discussions here on variegation this artificial form is caused by the introduction of Colour Break Virus which is also known in nature. I have invited the author of the on-line information to discuss this further here since in one of his posts he stated, "Leucoplast was a term I co-opted myself for variegation." It does appear that at least in some horticultural articles he quoted and information on JSTOR the term leucoplast is used in discussion of variegated aroids but I can't find it otherwise in any aroid literature. Steve Marak gave me several articles to read on variegation and I hope he will post those here as well for your consideration. Thanks! Steve HTML +More www.ExoticRainforest.com --------------020701080000000009040205-- --==============35993884036693590=

From: "J. Agoston" <agoston.janos123 at gmail.com> on 2010.12.30 at 06:45:35(21706) Steve, As far as I know leucoplast is a kind of cell organ which is the mother of other plastids, like chloroplast (found in leaves, makes it green) and chromoplast (mostly found in flowers, chromo means color). I think you may find an accurate description for it in the Jacob-Jäger-Ohmann's Botanical Compendium (http://books.google.hu/books?id=-PziPAAACAAJ&dq=Kompendium+der+Botanik&hl=hu&ei=EyocTaaHJ5Gs8QPS242PBQ&sa=X&oi=book_result&ct=result&resnum=1&ved=0CCYQ6AEwAA), unfortunately I don't remember the pages, it is most likely you'll find it in german version, but it is extremely useful. They have a part about plant and plant-organ evolution. I read the upper decription in that book like almost 10 years ago, so I might remember wrongly. Regards, Jan HTML +More Hungary 2010/12/28 Steve Lucas/Exotic Rainforest.com I have been following an internet discussion on variegation and have run into some terminology that at least appears strange. As I understand the discussion the term leucoplast is being used to possibly describe leaf variegation in Spathiphyllum. I was totally unfamiliar with the term so I ran it through my database of some 200 PDF aroid books and articles and not a single return was hit. I then pulled every botanical dictionary off my shelves and read the definition in each. Several listed nothing. For those like me that have no idea what the term means, I have compiled this definition from all my botanical dictionaries as well as a few on-line internet articles. If it is wrong, I would appreciate being corrected by some of our scientists: "Leucoplasts are a category of non pigmented plastids or organelles found in plant cells. An organelle is a specialized subunit within a cell that has a specified function. These colorless plastids are found in the cells of roots and the underground storage organs including underground stems such as tubers, bulbs and corms. The are involved in the storage functions of these organs including the storage of foods such as starches, lipids and proteins however some have no involvement at all in the storage process but instead process fatty acids as well as amino acids. Typically leucoplasts are much smaller than chloroplasts and have no involvement in the leaves of plants." Is the term leucoplast ever applicable to aroids? For those still not clear it just means the lack of green cells.. I realize that variegation is a natural process but it has been artificially induced in tissue culture as a result of economic reasons. People will often pay more for a variegated plant! As I understand from previous discussions here on variegation this artificial form is caused by the introduction of Colour Break Virus which is also known in nature. I have invited the author of the on-line information to discuss this further here since in one of his posts he stated, "Leucoplast was a term I co-opted myself for variegation." It does appear that at least in some horticultural articles he quoted and information on JSTOR the term leucoplast is used in discussion of variegated aroids but I can't find it otherwise in any aroid literature. Steve Marak gave me several articles to read on variegation and I hope he will post those here as well for your consideration. Thanks! Steve www.ExoticRainforest.com _______________________________________________ Aroid-L mailing list Aroid-L@www.gizmoworks.com http://www.gizmoworks.com/mailman/listinfo/aroid-l -- Protect the environment! Please think twice before printing this e-mail. || Védjük környezetünket, csak szükség esetén nyomtassa ki ezt a levelet! --000e0ce0488a67dbf704989b08c0-- --==============70017000155541890=

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