Plant physiology

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

Exogenous 24-Epibrassinolide Alleviates Effects of Salt Stress on Chloroplasts and Photosynthesis in Robinia pseudoacacia L. Seedlings

Abstract: The brassinosteroids (BRs) constitute a recently defined class of plant hormone that can enhance the resistance of plants to multiple stresses. However, the effects of BRs on salt-stressed woody plants, notably on photosynthesis and chloroplast ultrastructure, have received little attention. Black locust (Robinia pseudoacacia L.) seeds and seedlings were pretreated with 1.04 µmol L− 1 24-epibrassinolide (24-epiBL) by soaking and root dipping, respectively, and grown under non-saline or saline conditions (0, 100, 200 mmol L− 1 NaCl). Salinity stress decreased photosynthesis, chlorophyll concentration, transpiration, and stomatal conductance but also decreased the water-use efficiency, while chlorophyll fluorescence indicated a decrease in photochemical quenching and in maximum potential quantum efficiency. Indicators of oxidative stress (for example, H2O2 and antioxidant enzymes), membrane leakage, and amounts of Na+ ions in leaves and chloroplasts were increased and, at the highest stress, chloroplast ultrastructure was severely disrupted. Exogenous 24-epiBL improved membrane stability and reduced foliar Na+ levels, while substantially alleviating stress-induced changes in photosynthetic gas exchange. Improvements in chlorophyll content and indicators of oxidative stress were not as large but were still highly significant. Thylakoid membrane structure was protected. Both methods of applying 24-epiBL were effective, but root-dipped seedlings performed marginally better. The results suggest that treatment of black locust seedlings with 24-epiBL prior to planting may improve performance and aid establishment on salt-affected soils.

Foliar application of Sili-K® increases chestnut (Castanea spp.) growth and photosynthesis, simultaneously increasing susceptibility to water deficit

Abstract: The beneficial effects of Si have mainly been observed in herbaceous plants, while little is known about its role in deciduous trees. The aim of this work was to evaluate the effect of foliar application of Si on chestnut leaf growth, photosynthesis and water relations in the presence of short, but intense water deficit. Sili-K® solution (containing 0.12 % Si and 0.15 % K) was repeatedly (× 3) sprayed onto leaves of potted chestnut plantlets and irrigation was suspended 7 weeks later, for 8 days. Leaf growth, anatomy, as well as physiological and biochemical traits of the plantlets were studied. Si application enhanced chestnut growth, due to increased photosynthetic traits, including higher chlorophyll content and chlorophyll a to b ratio, photochemical efficiency of PSII, gas exchange (stomatal conductance, transpiration rate, net CO2 assimilation) and oxygen evolution rate. Meanwhile, Si yielded larger and thinner leaves, higher xylem, specific leaf area and transpiration rate, thus being beneficial to the tree in absorbing sunlight energy for photosynthesis and in alleviating heat stress. However, Si also lowered leaf sap osmotic pressure, causing the plant to lose water more quickly, thus being more susceptible to water stress. Si improved chestnut photosynthesis, growth, and heat stress tolerance, but it also increased the susceptibility to drought.

Enhanced salinity tolerance in transgenic maize plants expressing a BADH gene from Atriplex micrantha

Abstract: Salinity is an adverse environmental stress that limits the yield and quality of maize. As one of the most important osmolytes present in higher plants, glycinebetaine helps stabilize metabolism in plant cells and protects the constituents of cells from damage. In this study, a gene from Atriplex micrantha that encodes betaine aldehyde dehydrogenase was introduced by Agrobacterium-mediated transformation into maize inbred lines Zheng58 and Qi319 under the control of the maize ubiquitin promoter. Putative transgenic plants were confirmed by PCR and Southern blotting analysis. The transgenic maize plants expressed higher amounts of betaine aldehyde dehydrogenase activity and also grew better than the WT plants under NaCl stress. Compared with the wild type, the transgenic plants had increased fresh weight, lower malondialdehyde content, lower relative electrical conductivity, higher chlorophyll content, taller plant height, and higher grain yield under salt stress, which indicated that the expression of BADH gene in maize seedlings enhanced the salt tolerance of these plants.

Synergistic response of auxin and ethylene on physiology of Jatropha curcas L.

Abstract: Jatropha curcas L. is a versatile crop since all its plant material is brought to use either as energy source, industrial or medicinal purpose. Several studies are ongoing in different parts of the world to optimize, enhance and exploit the growth, fruiting cycle and different developmental stages of the plant so that the economic yield of the plants can be utilized to the fullest limits. Foliar application of plant growth regulators such as ethrel (an ethylene releasing compound), indole acetic acid (IAA) and naphthalene acetic acid (NAA) at 50, 100 and 150 ppm, was found to influence different morpho-physiological characters in Jatropha curcas L, such as plant height, collar diameter, tree spread, flower initiation, number of inflorescence per plant, number of male and female flowers per inflorescence, and the ratio of male: female flowers per inflorescence. Moreover, the leaves chlorophyll content, Fv/Fm value, nitrate reductase activity and proline content were also affected by synergistic response of auxin and ethylene. As higher the plant growth regulators concentration higher was the synergic effect on the Jatropha curcas L physiology.

Cell-specific gene expression of phosphate transporters in mycorrhizal tomato roots.

Abstract: Phosphorus (P) is an essential plant nutrient and is limiting for plant growth in most natural ecosystems as well as in agricultural production throughout the world. In arbuscular mycorrhizal (AM) symbiosis, the fungus obtains carbon from the plant and transfers mineral nutrients, like phosphate (Pi), from the soil to the root cells. Mycorrhizal plants can acquire Pi directly from the soil through plant-specific Pi transporters (the direct uptake pathway) or through fungal uptake and transport systems (the mycorrhizal uptake pathway). The study of plant Pi transporters and of their functioning therefore represents a key point for plant physiology. In this work, after a morphological analysis of tomato mycorrhizal roots, we have used the laser microdissection technology to collect cortical, epidermal, and central cylinder cells with the aim of analyzing the expression of the five so far identified tomato Pi transporter genes in the different root tissues. Using reverse transcriptase PCR analysis, LePT1 and LePT2 transcripts were detected in the epidermal and cortical cells, while LePT3, LePT4, and LePT5 transcripts were confirmed to be exclusive of arbuscule-containing cells. Despite the presence of mRNA in all the analyzed cell populations, no expression of the known tomato Pi transporter genes was observed in the central cylinder cells, irrespective of the presence of the AM fungus.