The regulation of respiration on plant growth and development of Fallopia japonica, Japanese knotweed

Shearman, Julia (2016) The regulation of respiration on plant growth and development of Fallopia japonica, Japanese knotweed. Doctoral thesis (PhD), University of Sussex.

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Fallopia japonica, or Japanese knotweed is a rhizomatous perennial herb native to East Asia; most notably Japan, China and Korea. Upon discovery of this species and subsequent import to Europe in the 1840’s, it was considered an esteemed ornamental plant – winning the medal for the ‘most interesting new plant of the year’ in 1847.

F. japonica soon became known as a menace rather than a champion, when it began to spread throughout its new environment, spreading to gardens and nurseries and regenerating from discarded plant fragments. The species ability to cause environmental damage has earnt it a place in the ‘top 100 world’s worst most invasive alien species’ list.

Commercially available herbicides have proven have little effect on F. japonica, and to be successful require many repeat applications. The plant can grow up to 10 cm per day during the early budding and shoot stage and can easily dominate an environment when left unchecked. A key objective of this research was to determine the biochemical pathways of energy generation particularly during the rapid phase of growth with the longer term goal of identifying potential inhibitors of this process which may have commercial opportunities.

Very little research is available regarding the biochemistry of growth of F. japonica, thus detailed protocols were required to be established and optimised prior to biochemical investigations.

Mitochondrial isolations and following respiratory activity measurements were performed on F. japonica prepared from naturalised plants. Such mitochondrial samples were found to have a very low respiratory rates when compared to mitochondria isolated from other species such as Arum maculatum. This was confirmed following an analysis of the respiratory complexes via electrophoresis, which revealed that all complexes were of low abundance in comparison with other plant species. Transmission electron microscopy also revealed that the numbers and volumes of mitochondria in budding tissue were considerably fewer and larger than those observed in other rapidly expanding plant tissues - providing further confirmation of the respiratory measurements.

In an attempt to overcome the small yield associated with mitochondrial isolations, research is also presented on the generation, optimisation and characterisation of suspension cultures from F. japonica explants. Suspension cultures were shown to have almost identical characteristics in terms of mitochondrial protein complement and respiratory capacity as observed in bud and shoot isolations. Preliminary mass spectroscopy data indicated a large proportion of ATP synthase subunits were present in the isolated mitochondrial fractions from leaf, bud, shoot and suspension cultures. Glycolytic analysis of fractions isolated from suspension cultures were also undertaken the outcome of which are discussed in terms of the energy generation pathways within F. japonica and the implications of how such pathways may be controlled.

Item Type: Thesis (Doctoral)
Schools and Departments: School of Life Sciences > Biochemistry
Subjects: Q Science > QD Chemistry > QD0241 Organic chemistry > QD0415 Biochemistry
Q Science > QK Botany > QK0710 Plant physiology
Depositing User: Library Cataloguing
Date Deposited: 03 Aug 2016 11:55
Last Modified: 03 Aug 2016 11:55

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