Plant physiology

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

Proteins responding to drought and high-temperature stress in Populus × euramericana cv. ‘74/76’

Abstract: Proteomic analysis provides a powerful method of studying plant responses to stress at the protein level. In order to study stress-responsive molecular mechanisms for Populus × euramericana cv. ‘74/76’, one of the most important forest plantation tree species in subtropical and temperate regions, we analyzed the response of 2-year-old cuttings of P. × euramericana cv. ‘74/76’ to drought and high temperature using two-dimensional gel electrophoresis. More than 1,000 reproducible leaf proteins were detected in the controls and treatments, and 26 proteins were found to change notably in abundance. We identified 13 proteins affected by drought stress and 11 proteins affected by high temperature. These proteins are mainly involved in photosynthesis such as ribulose-1,5-bisphosphate carboxylase/oxygenase large subunit and putative photosystem I reaction center subunit II precursor, and detoxification (manganese superoxide dismutase and methionine sulfoxide reductase A). Furthermore, the level of the photosynthesis proteins affected greatly by the imposed stress conditions was consistent with the observed noticeable decrease in net photosynthesis rate. These studies provides a fundamental data for future research on responses to drought and high temperature, two major factors limiting the growth of forest trees during summer under recent climatic warming.

What is germination

Abstract: An embryonic root (radicle) emerges from the seed and develops root hairs that bring in water and nutrients. In Fast Plants, an embryonic stem (hypocotyl) elongates, pushing the seed leaves (cotyledons) upwards through the soil. As they emerge from the soil the cotyledons expand. The cotyledons serve as an energy source until true leaves form. These events happen on Days 1, 2 and 3 of the Fast Plants life cycle (see Figure 1). For germination to take place, water and oxygen are needed and the temperature must be suitable.

Growth potential of Douglas Fir seedlings during dormancy.

Abstract: Summary The three experiments indicated that individual buds were the receptors for the growth stimulus produced by extended photoperiods during the autumn and winter. No evidence of transport of growth stimulatory materials from active to dormant bud was noted. Buds whose chilling requirements were fully satisfied initiated growth in response to favourable temperatures rather than to long photoperiods. Initiation of activity by lateral cambia required material exported from both expanding buds and mature foliage. No significant correlation between shoot and root growth was found. Although neither active buds nor applications of exogenous IAA or GA stimulated roots growth, both root elongation and initiation were found to be dependent upon some substance or substances, presumably hormones or carbohydrates, exported from mature foliage. Findings indicated that seedling physiology during the dormant period may be controlled by a changing balance in growth inhibitors and promoters.

Silicon deposition in roots minimizes the cadmium accumulation and oxidative stress in leaves of cowpea plants

Abstract: Silicon (Si) frequently accumulates in plants tissues, mainly in roots of dicotyledons, such as cowpea. By contrast, Cadmium (Cd) is a metal that is extremely toxic to plant metabolism. This research aims to investigate if the deposition of Si in root can reduce Cd contents and minimize its negative effects on leaves, measuring gas exchange, chlorophyll fluorescence, antioxidant metabolism, photosynthetic pigments and growth, which may explain the possible role of Si in the attenuation of Cd toxicity in cowpea. This study had a factorial design, with all factors completely randomized and two Cd concentrations (0 and 500 µM Cd, termed as – Cd and + Cd, respectively) and three Si concentrations (0, 1.25 and 2.50 mM Si). Si reduced Cd contents in the roots and in other plant organs, such as stems and leaves. The Si contents were highest in roots, followed by stems and leaves, which was explained by the passive absorption of Si. The application of Si promoted increase in both the macro- and micronutrient contents in all tissues, suggesting that Si mitigates the effect of Cd on nutrient uptake. Si attenuated Cd-mediated effects on light absorption of photosystem II (PSII), increasing the effective quantum yield of PSII photochemistry and the electron transport rate. Additionally, toxic effects induced by Cd on gas exchange were mitigated by the action of Si. Plants treated with Cd + Si showed increase in the activities of antioxidant enzymes and reductions in oxidant compounds; these modifications were promoted by Si via detoxification mechanisms. Increases in the photosynthetic pigments and growth of plants treated with Si and exposed to Cd stress were detected and were due to the reduced deterioration of cell membranes and maintenance of chloroplasts, which had positive repercussions on growth and development. This study validated the hypothesis that the accumulation of Si in roots induces benefits on metabolism and alleviates the toxic effects caused by Cd in leaves of cowpea.

Senescence‐induced loss in photosynthesis enhances cell wall β‐glucosidase activity

Abstract: A link between senescence-induced decline in photosynthesis and activity of β-glucosidase is examined in the leaves of Arabidopsis. The enzyme is purified and characterized. The molecular weight of the enzyme is 58 kDa. It shows maximum activity at pH 5.5 and at temperature of 50°C. Photosynthetic measurements and activity of the enzyme are conducted at different developmental stages including senescence of leaves. Senescence causes a significant loss in total chlorophyll, stomatal conductance, rate of evaporation and in the ability of the leaves for carbon dioxide fixation. The process also brings about a decline in oxygen evolution, quantum yield of photosystem II (PS II) and quantum efficiency of PS II photochemistry of thylakoid membrane. The loss in photosynthesis is accompanied by a significant increase in the activity of the cell wall-bound β-glucosidase that breaks down polysaccharides to soluble sugars. The loss in photosynthesis as a signal for the enhancement in the activity of the enzyme is confirmed from the observation that incubation of excised mature leaves in continuous dark or in light with a photosynthesis inhibitor 3-(3,4-dichlorophenyl)-1, 1-dimethylurea (DCMU) that leads to sugar starvation enhances the activity of the enzyme. The work suggests that in the background of photosynthetic decline, the polysaccharides bound to cell wall that remains intact even during late phase of senescence may be the last target of senescing leaves for a possible source of sugar for remobilization and completion of the energy-dependent senescence program.