Phyllody

Source: Wikipedia, the free encyclopedia.
"Frondescence" redirects here. For foliage and leaf development, see Leaf.
Not to be confused with Phyllode.
purple coneflower (Echinacea purpurea
)

Phyllody is the

environmental factors that result in an imbalance in plant hormones.[2] Phyllody causes the affected plant to become partially or entirely sterile, as it is unable to produce normal flowers.[1][3]

The condition is also known as phyllomorphy or frondescence;[4] though the latter may sometimes refer more generically to foliage, leafiness, or the process of leaf growth. Phyllody is usually differentiated from floral virescence, wherein the flowers merely turn green in color but otherwise retain their normal structure.[5] However, floral virescence and phyllody (along with witch's broom and other growth abnormalities), commonly occur together as symptoms of the same diseases.[6] The term chloranthy is also often used for phyllody (particularly flowers exhibiting complete phyllody, such that it resembles leaf buds more than flowers), though in some cases it may refer to floral virescence.[7]

History

In the late 18th century, the

German poet and philosopher Johann Wolfgang von Goethe noted strange-looking rose flowers where the flower organs were replaced by leafy or stem-like structures. This led him to hypothesize that plant organs arising from the stem are simply modifications of the same basic leaf organ. During growth, these organs naturally differentiate into specialized or generalized structures like petals or leaves. However, if certain factors interfere during the early growth stages, these organs can develop into something other than the original "plan of construction". He called this abnormal growth "metamorphosis" and it is the main topic of his essay Versuch die Metamorphose der Pflanzen zu erklären (1790), better known in English as the Metamorphosis of Plants.[2][5] Goethe's hypothesis was poorly received by other scientists during his time, but it is now known to be essentially correct. The concepts he discusses while describing metamorphosis is now known as homology, the basis of the modern science of comparative anatomy and a discovery that is usually credited to the English biologist Sir Richard Owen.[5][8]

In 1832, the German-

Belgian botanist Charles Jacques Édouard Morren also investigated the phenomenon in his book Lobelia (1851). Morren called the condition "phyllomorphy", and unlike Engelmann, Morren explicitly distinguished phyllomorphy (wherein the floral parts are replaced by leaf-like structures) from virescence (wherein the affected parts, not necessarily floral, turn green but retain the original form or structure).[5]

The term "phyllody" was coined by the

Ancient Greek φυλλώδης (phullodes, 'leaf-like').[9][10] Like Morren, Masters also distinguished phyllody from virescence. He acknowledged "frondescence" and "phyllomorphy" as synonyms of phyllody.[5]

Description

Phyllody is characterized by the partial or complete replacement of floral organs with true leaves. Phyllody can affect

androecium (stamens). Phyllody may be partial, affecting only some sets of floral organs or even only half of a set of floral organs (e.g. only three petals out of six in a single flower); or it can be complete, with all the floral organs replaced by leaves.[5]

anthers
have been replaced by small leaves.
leaves.
Longitudinal section of a normal developing rose hip

Phyllody of the bracts is common among plants which bear

dandelions, may also be affected.[5]

Sepals that exhibit phyllody are usually hard to detect due to fact that most sepals already resemble leaves. Close examination, however, can reveal differences in venation in normal sepals and sepals that exhibit phyllody. The full development of perfect leaves from sepals is more common among flowers that have united sepals (monosepalous) than in flowers with separated sepals (polysepalous).[5]

Phyllody of the petals can be expressed more mildly as a simple change in shape and color (in which case, it's more accurately virescence), or it can be expressed as fully formed leaves. It is more common among flowers which exhibit corollas of distinct petals (polypetalous) than in flowers in which the petals are fused into a single tube or bowl-like structure (monopetalous).[5]

Phyllody of the stamens is rare. In fact, the stamens are the least likely of the floral organs to be affected by phyllody. This is thought to be because the stamens are the most highly differentiated organs in flowers.[5]

In contrast, phyllody of the carpels is much more common than the corresponding changes in stamens. Usually, phyllody affects the proximal parts of the carpel (the ovary) more than the distal parts (the style and stigma). The ovule itself may be exposed on the edges or on the inner surface of the carpel if the ovary becomes leaf-like. If the ovule is affected by phyllody, it develops separately from the rest of the carpel. The best known example of phyllody of the carpels is found in the Japanese cherry (Prunus serrulata), in which one or both of the carpels can become leaf-like (although the distal half of the style and the stigma are usually unaffected). Incidentally, some Japanese cherry cultivars also exhibit "doubling" of the petals due to petalody, where a second corolla develops instead of stamens.[5][11]

Solanum melongena
)

Causes

Biotic

See also: Plant pathology

In many cultivated plants, phyllody is caused by infections of

biotic
factors include:

In addition to causing phyllody itself, insects and other ectoparasites also serve as disease

eriophyid mites, like the rose leaf curl mite (Phyllocoptes fructiplilus) which is known to be the primary vector of the rose rosette disease;[19][22] and the chrysanthemum rust mite (Paraphytoptus chrysanthemi) which transmits phytoplasma-caused phyllody in species of chrysanthemums.[23][24]

Abiotic

See also:
Physiological plant disorders

abiotic factors like hot weather or water stress that result in an imbalance in plant hormones during flowering can cause phyllody. These can usually be differentiated from phyllody caused by biotic factors by the simultaneous presence of healthy and abnormal flowers. When conditions normalize, the plants resume normal flowering. The susceptibility of plants to environmentally caused phyllody can be genetic.[2]

Artificial

Phyllody can be artificially induced by applying

flowering, and sex expression.[2]

Related floral teratology

See also: Carpellody

Other related floral development abnormalities are:

  • Petalody - The transformation of floral organs (usually the stamens) into petals.
  • Pistillody - The transformation of floral organs into
    pistils
    .
  • Sepalody - The transformation of floral organs into sepals or sepal-like bodies.
  • Staminody - The transformation of floral organs into stamens.

Phyllody in plant breeding

artificial selection has enabled phyllody to be expressed as a stable mutation.[2][25][26]

See also

References

  1. ^
    doi:10.1093/jxb/43.1.89
    .
  2. ^ a b c d e f g h i Sim, S.; Rowhani, A.; Golino, D. (2004). "Phyllody in Roses" (PDF). American Rose. 38 (18): 32–34.
  3. ISBN 9788188237692
    .
  4. ISBN 9780521438322
    .
  5. ^ a b c d e f g h i j k l Masters, M.T. (1869). Vegetable Teratology, an Account of the Principal Deviations from the Usual Construction of Plants. Robert Hardwicke. p. 240–281.
  6. ^
    ISBN 9781845935306
    .
  7. ISBN 9788182051874
    .
  8. ^ Gábor, Z. "Form as Movement in Goethe's The Metamorphosis of Plants". Technical University of Budapest. Retrieved 3 November 2012.
  9. ^ "Etymology of the English word phyllody". MyEtymology. Archived from the original on March 3, 2016. Retrieved 15 November 2012.{{cite web}}: CS1 maint: unfit URL (link)
  10. Perseus Project
    .
  11. ISBN 9780521438322
    .
  12. ^
    ISBN 9780521434027
    .
  13. ISBN 9788175330672
    .
  14. ISBN 9781555914011
    .
  15. ^ Akhtar, K.P.; Sarwar, G.; Dickinson, M.; Ahmad, M.; Haq, M.A.; Hameed, S. & Iqbal, M.J. (2009). "Sesame phyllody disease: its symptomatology, etiology, and transmission in Pakistan" (PDF). Turkish Journal of Agriculture and Forestry. 33: 477–486.
  16. ^ Nelson, S.C. "Phyllody". Hawaii Plant Disease, University of Hawaii at Manoa. Retrieved 10 November 2012.
  17. ^ "Diseases of Corn". National Agriculture and Food Research Organization (NARO), Japan. Retrieved 10 November 2012.
  18. ISBN 9788188237692
    .
  19. ^
    ISBN 9781601076724
    .
  20. ^ Srinivasan, R. (2009). Insect and Mite Pests on Eggplant (PDF). AVRDC Publication No. 09-729. AVRDC – The World Vegetable Center.
  21. ^ Tessema, T.; Obermeier, C.; Einhorn, G.; Seemüller, E.; Büttner, C. (2004). "Phyllody Disease of Parthenium Weed in Ethiopia". Pest Management Journal of Ethiopia. 8: 39–50.
  22. ^ Rose Rosette Disease (PDF). Report on Plant Disease No. 666. University of Illinois Extension. October 1999.
  23. S2CID 35050908
    .
  24. doi:10.1093/aesa/43.4.492
    .
  25. ISBN 9780824811280
    .
  26. ISBN 9780387774909
    .

External links

  • Media related to Phyllody at Wikimedia Commons
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