Phytotoxic property of the invasive plant Tithonia diversifolia and a phytotoxic substance

Tithonia diversifolia (Hemsl.) A. Gray (Asteraceae) is native to Mexico and Central America. The species is spreading quickly and has naturalized in more than 70 countries. It has often been recorded as a harmful invasive plant that disturbs native plant communities. Phytotoxic chemical interactions such as allelopathy between invasive plants and native plants have been reported to play an important role in the invasion. Evidence for allelopathy of T. diversifolia has accumulated in the literature over 30 years. Thus, the objective of this review was to discuss the possible involvement of allelopathy in the invasive potential of T. diversifolia. The extracts, root exudates, and plant residues of T. diversifolia inhibited the germination and growth of other plant species. The soil water and soil collected from T. diversifolia fields also showed inhibitory growth effects. The decomposition rate of T. diversifolia residues in soil was reported to be high. Phytotoxic substances such as sesquiterpene lactones were isolated and identified in the extracts of T. diversifolia. Some phytotoxic substances in T. diversifolia may be released into the soil through the decomposition of the plant residues and the exudation from living tissues of T. diversifolia, including its root exudates, which act as allelopathic substances. Those allelopathic substances can inhibit the germination and growth of neighboring plants and may enhance the competitive ability of the plants, make them invasive.

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Suaveolic Acid: A Potent Phytotoxic Substance ofHyptis suaveolens

The Scientific World JOURNAL ◽

10.1155/2014/425942 ◽

2014 ◽

Vol 2014 ◽

pp. 1-6 ◽

Cited By ~ 6

Author(s):

A. K. M. Mominul Islam ◽

Osamu Ohno ◽

Kiyotake Suenaga ◽

Hisashi Kato-Noguchi

Keyword(s):

Invasive Plant ◽

Methanol Extract ◽

Italian Ryegrass ◽

Lepidium Sativum ◽

Test Plant ◽

Garden Cress ◽

Aqueous Methanol ◽

Isolation And Identification ◽

Hyptis Suaveolens ◽

Phytotoxic Substance

Hyptis suaveolens(Lamiaceae) is an exotic invasive plant in many countries. Earlier studies reported that the aqueous, methanol, and aqueous methanol extract ofH. suaveolensand its residues have phytotoxic properties. However, to date, the phytotoxic substances of this plant have not been reported. Therefore, the objectives of this study were isolation and identification of phytotoxic substances ofH. suaveolens. Aqueous methanol extract of this plant was purified by several chromatographic runs through bioassay guided fractionation using garden cress (Lepidium sativum) as a test plant. Final purification of a phytotoxic substance was achieved by reverse phase HPLC and characterized as 14α-hydroxy-13β-abiet-8-en-18-oic acid (suaveolic acid) by high-resolution ESI-MS,1H-,13C-NMR, CD, and specific rotation. Suaveolic acid inhibited the shoot growth of garden cress, lettuce (Lactuca sativa), Italian ryegrass (Lolium multiflorum), and barnyard grass (Echinochloa crus-galli) at concentrations greater than 30 µM. Root growth of all but lettuce was also inhibited at concentrations greater than 30 µM. The inhibitory activities were concentration dependent. Concentrations required for 50% growth inhibition of suaveolic acid for those test plant species were ranged from 76 to 1155 µM. Therefore, suaveolic acid is phytotoxic and may be responsible for the phytotoxicity ofH. suaveolensplant extracts.

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Pretty (and) invasive: The potential global distribution of Tithonia diversifolia under current and future climates

Invasive Plant Science and Management ◽

10.1017/inp.2021.29 ◽

2021 ◽

pp. 1-25

Author(s):

Jessica M. Kriticos ◽

Darren J. Kriticos

Keyword(s):

Range Expansion ◽

Invasive Plant ◽

Southern China ◽

Climate Scenario ◽

Climatic Conditions ◽

Future Climate ◽

Global Distribution ◽

Future Climate Scenario ◽

Tithonia Diversifolia ◽

Environmental Weed

Abstract Tithonia diversifolia (Mexican sunflower) is an invasive plant, native to the New World, and an exemplary conflict species. It has been planted widely for its ornamental and soil fertility enhancement qualities and has become a notorious environmental weed in introduced habitats. Here we use a bioclimatic niche model (CLIMEX) to estimate the potential global distribution of this invasive plant under historical climatic conditions. We apply a future climate scenario to the model to assess the sensitivity of the modelled potential geographical range to expected climate changes to 2050. Under current climatic conditions, there is potential for substantial range expansion into southern Europe with moderate climate suitability, and in southern China with highly suitable climates. Under the near-term future climate scenario there is potential for poleward range expansion in the order of 200 – 500 km. In the tropics, climatic conditions are likely to become less favourable due to the increasing frequency of supra-optimal temperatures. In areas experiencing Mediterranean or warm temperate climates the suitability for T. diversifolia appears set to increase as temperatures warm. There are vast areas in North America, Europe and Asia (particularly China and India) that can support ephemeral populations of T. diversifolia. One means of enjoying the aesthetic benefits of T. diversifolia while avoiding the unwanted environmental impacts as it invades areas prized for environmental attributes is to try to prevent its spread into areas climatically suitable for establishment, and only allow it to be propagated in areas where it cannot persist naturally.

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