Plant physiology

About: Plant physiology is a research topic. Over the lifetime, 1537 publications have been published within this topic receiving 72038 citations.

Leaf colour polymorphisms: a balance between plant defence and photosynthesis

Abstract: Summary Whether plants use leaf colour to deter herbivores remains controversial. The warning signal hypothesis predicts that red pigmentation is adaptive by reducing herbivory; plants with predominantly red foliage should have higher fitness than those with green leaves. Despite many discussions, this prediction has rarely been tested, and alternative, non-exclusive hypotheses cannot be ruled out. We have exploited leaf colour polymorphism in Pseudowintera colorata to test the warning signal hypothesis and to address possible alternative explanations. Consistent with warning signals, redder foliage contained higher concentrations of polygodial, a sesquiterpene dialdehyde with strong antifeedant properties, and incurred less herbivory than green leaves. Redder plants hosted 22% fewer lepidopteran leafroller larvae than neighbouring green plants. However, contrary to the predictions of the hypothesis, there were no differences in fitness parameters between red and green plants. Overall leaf canopy colour was not a significant predictor of the number of seeds per fruit or of mean seed weight. This may be explained by differences in photosynthesis: green P. colorata leaves had 47% higher maximum CO2 assimilation rates than matched red leaves from neighbouring plants. These results indicate that the benefits of deterring insect herbivores by signalling may be balanced by the higher photosynthetic rate of non-signalling plants. A balance between signalling and photosynthesis is a novel mechanism for the maintenance of leaf colour polymorphisms in nature. Synthesis. Anthocyanin pigments may simultaneously serve multiple functions within leaves, and individuals of the same plant species may use different strategies to cope with insect herbivores. Therefore, investigations into the role of these pigments in plant–insect interactions need to consider plant physiology and the diversity of plant defence mechanisms.

Effect of synthetic and biosynthesized silver nanoparticles on growth, physiology and oxidative stress of water hyacinth: Eichhornia crassipes (Mart) Solms

Abstract: Silver (Ag) nanoparticles (NPs) are synthesized by several methods and are being widely used in various fields of science. In recent times, evaluation of their toxicological effects on environment, especially to the plant ecosystems has attained special attention. In this study, effect of synthesized AgNPs [chemically (S-AgNPs) and/or biologically (B-AgNPs)] on the growth and physiology of an aquatic plant water hyacinth—Eichhornia crassipes (Mart) Solms was evaluated. Water hyacinth plants were treated with S-AgNPs and B-AgNPs at different concentrations of 1, 10 and 100 mg L−1and growth was monitored for 5 days. Decreased growth of hyacinth was observed only on fifth day in treatments with S-AgNPs treatment alone but not for B-AgNPs. Further, the atomic absorption spectroscopy results (at 100 mg L−1 concentration) showed a higher accumulation of S-AgNPs over the B-AgNPs in various parts of the treated plants. Biochemical analysis on day five in B-AgNPs treated leaf extracts revealed an increase in carbohydrate and protein levels, and a decrease in phenol and chlorophyll content. In contrary, S-AgNPs treated leaf extracts did not show any significant changes in carbohydrate and protein levels, however, observed a significant increase in phenol and chlorophyll content. Interestingly, S-AgNP treatment increased the activities of antioxidative enzymes, such as catalase, peroxidase and superoxide dismutase. No significant differences were measured in plants treated with B-AgNPs when compared to normal plants which may reveal that these B-AgNPs instead enhanced the plant growth with a fewer minor effects on water hyacinth plants over S-AgNPs.

Physiology of resistance to fungal diseases in plants

Abstract: Phys io logica l Res is tance Fac tors ........................................................................................................................................ 97 G e n e r a l .............................................................................................................................................................................................. 97 Metabo l i sm, N u t r i t i on ......................................................................................................................................................... 99 Inh ib i to rs , T o x i n s ..................................................................................................................................................................... 102 H y p e r s e n s i t i v i t y ....................................................................................................................................................................... 104 Photoa lex ins ................................................................................................................................................................................... 105 Phenols and Re la t ed C o m p o u n d s ........................................................................................................................... 106 G r o w t h Substances and E n z y m e s ........................................................................................................................... 112