MUTATIONS IN PLANTS - INFO
MUTATIONS in PLANTS
These abnormalities include:
It has recently been found that peloria is not a trait propagated by DNA, but instead involves an epigenetic process of silencing a specific gene by DNA methylation in the environment. The peloric nature is happily passed on between generations, just like it would be if it were down to changes in the DNA sequence. But the DNA sequence remains un-altered in epigenetic changes. This is similar to the once discredited Lamarckism (although your Author had always thought that there was some element of truth about Lamarckism), where the environment leads to heritable changes in the genome - which is now found to be not totally without foundation, although specific examples are rare (and most examples involve epigenetic changes to the DNA: methylation).
Peloria is frequently found in Foxgloves, where usually it is the topmost flower which reverts to the older form of flower shape with radial symmetry rather than the more recently evolutionary development of bilateral symmetry - such as normally exhibited by Foxgloves, Vetches, and a great many other flowers. It is usually only the topmost flower which can exhibit peloria; all the others are normal with bilateral symmetry.
Peloria is more usually of epigenetic origin and recessive (more infrequent than transmissable), although it can be instigated by environmental happenings. These changes to the epigenome can persist in the population but only reveal themselves by a peloric flower appearing from time to time.
Fasciation is a result of an aberration in the apical meristem - the growing tip of the shoot which consists of undifferentiated cells (cells which have not yet been assigned to grow into petals, veins, anthers, etc etc). The apical meristem can become damaged (by several means - physical damage by insects, fungi, bacteria, nuclear radiation, weed-killers, un-suitable growing conditions, heavy metals in the soil, etc). When such damage is occasioned disrupted growth can occur. Fasciation can be one result of this abnormal growth pattern. Fasciation can affect just the stem, just the flowerhead, or both together. Sometimes the whole plant can be fasciated.
Fasciation can also be an inherited condition, where several nearby Daisies or Dandelions (or any other plants) are fasciated. A few plants sold horticulturally have been specially bred to be fasciated, such as the Amaranth known as Cockscomb celosia which has gaudy colourful fasciated flowerheads. The
Phyllody is common in members of the Plantago genus such as Ribwort Plantain, as well as in some other plants such as Hop, Dahlias or Dandelions. It is more commonly expressed in those flowers which are polypetalous (with more than one petal) rather than the monopetalous plants which have but one petal (the petals being fused into the form of a bowl or tube) such as Daffodils.
The causes of phyllody are manifold, including phytoplasmas, virii - such as those which cause Rose rosette disease, fungi - such as smuts and rusts, water moulds - such as Sclerophthora macrospora and last but probably not least by insect damage. But phyllody can also be caused by environmental factors such as the weather occasioning drought or heat stress amongst many others which may create a hormone imbalance. Applying growth hormones could have the same effect - after all, phyllody is the plant growing parts of itself where it should not - and the right parts grow where they should orchestrated by the inter-play and concentrations of many different hormones, so it is no surprise that upsetting the hormone balances by direct application may result in the plant growing parts of itself where it shouldn't.
Your Author thinks this does not apply to those plants which normally have green-coloured flowers, such as those of Moschatel, Lady's Mantles, Dog's Mercury, Bog Orchid, Parsley Piert, White Bryony, Golden-saxifrages, Common Twayblade, some Hellebores, etc.