Physiological and Biochemical Responses to Water Stress and Salinity of the Invasive Moth Plant, Araujia sericifera Brot., during Seed Germination and Vegetative Growth

Abstract

Araujia sericifera is an invasive plant with an increasing presence in South East Spain, where it produces damage to native trees and shrubs and citric orchards. As the climatic conditions in the study area are becoming harsher due to the climate change, the stress tolerance of this species has been studied during germination and vegetative growth. Growth parameters, photosynthetic pigments, ion accumulation, and antioxidant mechanisms were analysed in plants that were subjected to water deficit and salt stress. Seed germination was reduced by salinity but 50% of the seeds still germinated at 50 mM NaCl. The ungerminated seeds did not lose their germination capacity as shown in ‘recovery’ germination assays in distilled water. Germination was less affected by osmotic stress that was induced by polyethylene glycol (PEG), and germination velocity increased in the recovery treatments after exposure to NaCl or PEG. Plant growth was practically unaffected by 150 mM NaCl but inhibited by higher NaCl concentrations or severe drought stress. Nevertheless, all the plants survived throughout the experiment, even under high salinity (600 mM NaCl). A. sericifera relative stress tolerance relies, at least to some extent, on effective antioxidant mechanisms that are based on flavonoid biosynthesis and the activation of antioxidant enzymes such as superoxide dismutase, ascorbate peroxidase, and glutathione reductase.

Effect of Water Deficit on Germination, Growth and Biochemical Responses of Four Potentially Invasive Ornamental Grass Species

“…Invasive species’ ability to germinate under a wide range of ecological niches has been attributed to their tolerance to a broad spectrum of adverse environmental conditions [ 19 , 55 ]. Reports documenting such germination potential are continuously increasing as part of the risk assessment necessary for their management [ 56 , 57 ].…”

Salt and Water Stress Tolerance in Ipomoea purpurea and Ipomoea tricolor, Two Ornamentals with Invasive Potential

“…The two Ipomoea species were also characterised by rapid seedling growth, which may play an additional role in outcompeting species with slower germination and seedling development [51]. Another exceptionally relevant trait characterising many invasive species is their ability to germinate in a wide range of environmental conditions [51,[53][54][55]. Global warming is increasing the risk of exposure to unfavourable conditions and favours species with greater abiotic resistance.…”

Comparative Analysis of Tolerance to Salt Stress and Water Deficit in Two Invasive Weeds of the Genus Erigeron (Asteraceae)

“…Germination time (MGT) did not vary from the control. Salt and osmotic stress tolerance were reported in other invasive weeds of different genera, such as, Araujia [ 15 ], Amaranhus [ 14 ], Chenopodium [ 69 ], and Cenchrus [ 70 ], which thrive in disturbed habitats (either altered by natural or anthropogenic forces) due to increased plant fitness through functional and adaptive traits [ 71 ]. The stronger effects of NaCl than of PEG can be explained by the ionic toxicity, as salinity has a toxic component in addition to the increased external osmotic potential that reduces water uptake during imbibition also produced by PEG.…”

“…For this reason, an increasing number of studies are being conducted on responses to drought and salinity not only in model plants, but also in crops and their wild relatives [ 4 , 5 , 6 , 7 , 8 ]. Although unravelling functional responses to environmental factors in invasive plants is gaining interest [ 9 ], analysis of stress tolerance and mechanisms underlying stress responses are scarce in such species [ 10 , 11 , 12 , 13 , 14 , 15 ].…”