Plant physiology

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

Cellular response of light/dark-grown green alga Chlorella vulgaris Beijerinck (Chlorophyceae) to exogenous adenine- and phenylurea-type cytokinins

Abstract: Treatment exposed to light Chlorella vulgaris Beijerinck (Chlorophyceae) with adenine- (BA, Kin, Z) and phenylurea-type (DPU) cytokinins effects positively on alga viability by 1.5- to twofold increase in cell number, chlorophylls, carotenoids, monosaccharides and glycolate content as well as NADH-dependent hydroxypyruvate reducing enzyme activity (NADH-HPR) extensively involved in carbon metabolism. Cytokinins enhance nitrogen assimilation by stimulation of NADH-dependent glutamate dehydrogenase (NADH-GDH) aminating activity finally leading to higher protein level and its secretion as well as polypeptide accumulation in the range of molecular weight 12–195 kDa. In the dark, cytokinins mimic the regulatory effect of light upon algal cell division, metabolite content and stimulate carbon recycling for Calvin cycle reactions by enhancing of light-dependent NADH-HPR activity. The delaying of protein degradation and stimulation of their secretion to environment, triggering polypeptide accumulation and twofold higher NADH-GDH activity catalysing amino acids biosynthesis are observed in the dark-grown microalgae in response to cytokinins. Chlorella vulgaris exhibits sensitivity on cytokinins in the following order of their stimulating properties: DPU > Z > Kin > BA in both light and dark conditions. Understanding of cytokinin role in lower plants under different light conditions could be a step toward the elucidation of the evolution of hormone regulation and their action at molecular level.

Foliar spray of Auxin/IAA modulates photosynthesis, elemental composition, ROS localization and antioxidant machinery to promote growth of Brassica juncea

Abstract: Auxins (Aux) are primary growth regulators that regulate almost every aspect of growth and development in plants. It plays a vital role in various plant processes besides controlling the key aspects of cell division, cell expansion, and cell differentiation. Considering the significance of Aux, and its potential applications, a study was conducted to observe the impact of indole acetic acid (IAA), a most active and abundant form of Aux on Brassica juncea plants growing under natural environmental conditions. Different concentrations (0, 10−10, 10−8, 10−6 M) of IAA were applied once in a day at 25-day stage of growth for 5 days, consecutively. Various parameters (growth, photosynthetic, biochemical, oxidative biomarkers and nutrient composition) were assessed at different days after sowing (DAS). Scanning electron microscopy (SEM) of leaf stomata, reactive oxygen species (ROS) localization in leaf and roots, and confocal microscopy were also conducted. The results revealed that all the IAA concentrations were effective in growth promotion and ROS reduction, however, the 10−8 M of IAA exhibited the maximum improvement in all the above mentioned parameters as compared to the control.

Growth rate of fine root systems influences rootstock tolerance to replant disease

Abstract: Aims Plant tolerance to herbivory has often been linked to plant growth rate, with faster growing plants that present high tissue turnover rates expected to be more tolerant than slower-growing plants. We tested whether this relationship also holds for rootstock growth rate and tolerance to apple replant disease (ARD).

Effects of high CO2 levels on dynamic photosynthesis: carbon gain, mechanisms, and environmental interactions.

Abstract: Understanding the photosynthetic responses of terrestrial plants to environments with high levels of CO2 is essential to address the ecological effects of elevated atmospheric CO2. Most photosynthetic models used for global carbon issues are based on steady-state photosynthesis, whereby photosynthesis is measured under constant environmental conditions; however, terrestrial plant photosynthesis under natural conditions is highly dynamic, and photosynthetic rates change in response to rapid changes in environmental factors. To predict future contributions of photosynthesis to the global carbon cycle, it is necessary to understand the dynamic nature of photosynthesis in relation to high CO2 levels. In this review, we summarize the current body of knowledge on the photosynthetic response to changes in light intensity under experimentally elevated CO2 conditions. We found that short-term exposure to high CO2 enhances photosynthetic rate, reduces photosynthetic induction time, and reduces post-illumination CO2 burst, resulting in increased leaf carbon gain during dynamic photosynthesis. However, long-term exposure to high CO2 during plant growth has varying effects on dynamic photosynthesis. High levels of CO2 increase the carbon gain in photosynthetic induction in some species, but have no significant effects in other species. Some studies have shown that high CO2 levels reduce the biochemical limitation on RuBP regeneration and Rubisco activation during photosynthetic induction, whereas the effects of high levels of CO2 on stomatal conductance differ among species. Few studies have examined the influence of environmental factors on effects of high levels of CO2 on dynamic photosynthesis. We identified several knowledge gaps that should be addressed to aid future predictions of photosynthesis in high-CO2 environments.