Plant physiology

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

Effects of polyploidization on the contents of photosynthetic pigments are largely population-specific

Abstract: The contents of photosynthetic pigments are an important indicator of many processes taking place in the plant body. Still, however, our knowledge of the effects of polyploidization, a major driver of speciation in vascular plants, on the contents of photosynthetic pigments is very sparse. We compared the contents of photosynthetic pigments among natural diploids, natural tetraploids, and synthetic tetraploids. The material originated from four natural mixed-cytotype populations of diploid and autotetraploid Vicia cracca (Fabaceae) occurring in the contact zone between the cytotypes in Central Europe and was cultivated under uniform conditions. We explored whether the contents of pigments are primarily driven by polyploidization or by subsequent evolution of the polyploid lineage and whether the patterns differ between populations. We also explored the relationship between pigment contents and plant performance. We found very few significant effects of the cytotype on the individual pigments but many significant interactions between the cytotype and the population. In pair-wise comparisons, many comparisons were not significant. The prevailing pattern among the significant once was that the contents of pigments were determined by polyploidization rather than by subsequent evolution of the polyploid lineage. The contents of the pigments turned out to be a useful predictor of plant performance not only at the time of material collection, but also at the end of the growing season. Further studies exploring differences in the contents of photosynthetic pigments in different cytotypes using replicated populations and assessing their relationship to plant performance are needed to assess the generality of our findings.

The effect of end of day far-red light on regulating flowering of short-day strawberry ( Fragaria × ananassa Duch. сv. Paros) in a long-day situation

Abstract: The effects of manipulation of phytochrome state and plant age were tested on flowering strawberry (Fragaria × ananassa Duch. cv. Paros) using end of day far red light (EOD-FR) under undesirable environmental conditions (high temperature and long day). The first and second experiments examined the effects of EOD-FR on flower induction, level of phytochrome and carbohydrates (starch, sucrose, fructose, and glucose), which were variable along with acid invertase enzyme. In the first experiment, there was no flower emergence, but in the second experiment, induction occurred in plants exposed to 6 h of EOD-FR for 32 cycles. The third experiment tested the effect of far red light (6 h + 32 d) on plants of 8, 10, and 12 weeks of age, and induction occurred in 12-week-old plants. The results of experiments II and III indicated that in the induced plants, the amount of phytochrome (Pr) increased. Furthermore, a higher level of sucrose was observed in induced plants, but the level of starch was lower. Nevertheless, amounts of glucose, fructose, and invertase enzyme did not change significantly, although they did show a slight increase in induced plants. These results provide evidence that a light-quality pathway exists that acts on regulation of flowering time in short-day strawberry cultivation.

Photosynthesis research in India: transition from yield physiology into molecular biology.

Abstract: Photosynthesis research in India can be traced back several thousand years, with the mention of the Sun energizing the plants, which form food for all living creatures on the earth (from the Mahabharata, the great epic, ca. 2600 B.C.) and the report of Sage Parasara (ca. 100 B.C.) on the ability of plants to make their own food, due to their pigments. With the pioneering studies by Sir Jagdish Chandra Bose, work on photosynthesis proceeded steadily during the first half of the 20th century. Some of the classic reports during this period are: malate metabolism in Hydrilla, spectrophotometric estimation of chlorophylls, importance of spectral quality for photosynthesis — an indication of two photosystems, photoinactivation of photosynthesis, and importance of flag leaf photosynthesis to grain yield. After the 1960s, there was a burst of research in the areas of physiology and biochemistry of carbon assimilation and photochemistry. A significant transition occurred, before the beginning of new millennium, into the area of molecular biology of chloroplasts, regulation of photosynthesis and stress tolerance. Future research work in India is geared to focus on the following aspects of photosynthesis: elucidation/analysis of genes, molecular biology/evolution of enzymes, development/use of transgenics and modeling.

The interaction of light irradiance with ethylene in regulating growth of Helianthus annuus shoot tissues

Abstract: Shade light found in ecological niches where plants are growing under a canopy or in proximity of taller neighbouring vegetation consist mainly of two separate light signals: low red to far-red ratio and low photosynthetically active radiation (PAR). The effect of the latter on the growth of 7-day old sunflower shoots was examined by assessing hypocotyl, cotyledon and leaf tissue growth under three varying PAR levels: near-normal of 1,000 μmol m−2 s−1, low of 100 μmol m−2 s−1 and very low of 10 μmol m−2 s−1. Then, the possible interaction between PAR signaling and ethylene in regulating growth of these sunflower tissues was investigated. The results showed that gradual decrease in PAR level increases hypocotyl elongation and decreases ethylene evolution. However, gradual decrease in PAR level decreases cotyledon and leaf growth and increases ethylene evolution. Thus it seems possible that PAR regulation of shoot growth is mediated by changes in ethylene evolution in tissue specific manner. This hypothesis was supported by experiments with the ethylene releasing factor, ethephon, and the ethylene biosynthesis inhibitor, AVG, as well as by transfer experiments where sunflower seedlings were transferred from one PAR regime to another with subsequent growth and ethylene measurements.

Effects of nitrate and ammonium on growth of Arabidopsis thaliana plants transformed with the ARR5::GUS construct and a role for cytokinins in suppression of disturbances induced by the presence of ammonium

Abstract: Determination of physiologically active cytokinins in transformed Arabidopsis thaliana (L.) Heynh. plants (ecotype Wassilevskija) by means of the ARR5::GUS gene expression analysis and by the immunohistochemical assay demonstrated an increase of the cytokinin content during leaf growth and its decrease after growth cessation. After leaf growth cessation cytokinins (CKs) were found only in chloroplasts. Nitrate but not ammonium salt increased the cytokinin content in leaves. The replacement of nitrate in nutrient medium with ammonium salts suppressed leaf and root growth and decreased the content of physiologically active CKs in them. In plants cultivated on a media with NH4Cl as a sole nitrogen source, 10–9 M trans-zeatin several-fold activated leaf growth, prevented a decrease in the chlorophyll a and b content, and reduced proline accumulation indicating suppression of the NH4Cl stress action. Thus, negative effects of NH4Cl as a sole nitrogen source depended on the cytokinin shortage.