Plant physiology

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

Transformation of Lotus corniculatus Plants with Escherichia coli Asparagine Synthetase A: Effect on Nitrogen Assimilation and Plant Development

Abstract: Asparagine and glutamine are major forms of nitrogen in the phloem sap of many higher plants. In vascular plants, glutamine-dependent asparagine synthetase (AS) is the primary source of asparagine. In Escherichia coli, asparagine is synthesized by the action of two distinct enzymes, AS-A which utilizes ammonia as a nitrogen donor, and AS-B which utilizes both glutamine and ammonia as substrates, but with a preference for glutamine. In this study, the possibility to endow plants with ammonia-dependent AS activity was investigated by heterologous expression of E. coli asnA gene with the aim to introduce a new ammonium assimilation pathway in plants. The bacterial gene is placed under the control of light-dependent promoters, and introduced by transformation into Lotus corniculatus plants. Analysis of transgenic plants has revealed a phenomenon of transgene silencing which has prevented asnA expression in several transgenics. The asnA-expressing plants are characterized by premature flowering and reduced growth. A significant reduction of the total free amino acid accumulation in transgenic plants is observed. Surprisingly, the content of asparagine in wild-type plants is about 2.5-fold higher than that of transgenic plants. While glutamine levels in transgenic plants are about 3–4-fold higher than those in wild-type plants, aspartate levels are significantly lower. Transformation with asnA also induced a significant reduction of photosynthesis when measured under saturated light and ambient CO2 conditions.

Activities of antioxidant system components and polyphenol oxidase in ontogeny of lawn grasses under megapolis conditions

Abstract: The activities of antioxidants enzymes (peroxidase (POX) and catalase (CAT)), the contents of non-enzymatic antioxidants (vitamin C, carotenoids), and the activity of polyphenol oxidase (PPO) were studied in vegetative organs of red clover (Trifolium pratense L.) and meadow-fescue (Festuca pratensis Huds.) growing under city conditions. The plants of three ages (virginal (V), generative (G), and subsenyl (SS)) were analyzed. The highest POX and PPO activities were characteristic of G plants, whereas CAT was most active in V plants. The content of low-molecular-weight antioxidants depended on species specificity and developmental stage and also on environment pollution. The content of ascorbate (vitamin C) declined linearly with plant development. Medium pollution also reduced the ascorbate content in tested plant leaves and roots. In contrast, the content of carotenoids increased with the increased activity of anthropogenic factors. The highest content of the pigments was in G plants. At all developmental stages and in all habitats, meadow-fescue (tolerant species) was characterized by the lower content of studied compounds than red clover (sensitive species). Thus, anthropogenic medium pollution resulted in the peroxide group accumulation, POX and PPO activation, carotenoid accumulation, and the ascorbate content decline in the vegetative tissues during the entire ontogeny of tolerant and sensitive lawn plants.

Nitrogen Metabolism is Affected in the Nitrogen-Deficient Rice Mutant esl4 with a Calcium-Dependent Protein Kinase Gene Mutation.

Abstract: Calcium-dependent protein kinases are involved in various biological processes, including hormone response, growth and development, abiotic stress response, disease resistance, and nitrogen metabolism. We identified a novel mutant of a calcium-dependent protein-kinase-encoding gene, esl4, by performing map cloning. The esl4 mutant was nitrogen deficient, and expression and enzyme activities of genes related to nitrogen metabolism were down-regulated. ESL4 was mainly expressed in the vascular bundles of roots, stems, leaves, and sheaths. The ESL4 protein was localized in the cell membranes. Enzyme activity and physiological index analyzes and analysis of the expression of nitrogen metabolism and senescence-related genes indicated that ESL4 was involved in nitrogen metabolism. ESL4 overexpression in transgenic homozygous T2 plants increased nitrogen-use efficiency, improving yields when little nitrogen was available. The seed-set rates, yields per plant, numbers of grains per plant, grain nitrogen content ratios, and total nitrogen content per plant were significantly or very significantly higher for two ESL4 overexpression lines than for the control plants. These results suggest that ESL4 may function upstream of nitrogen-metabolism genes. The results will allow ESL4 to be used to breed novel cultivars for growing in low-nitrogen conditions.

Understanding plant growth regulators, their interplay: For nursery establishment in fruits

Abstract: The term plant growth regulator (PGR) includes naturally occurring plant growth substances or phytohormones, as well as synthetic compounds which mostly are chemical analogs, materials that alter hormone levels (hormone releasing agents or synthesis inhibitors) and materials that alter hormone sensitivity. The concentrations of hormones required for plant responses are very low (10-6 to 10-5 mol/l). Because of these low concentrations, it has been very difficult to study plant hormones and only since the late 1970’s have scientists been able to start piercing together their effects and relationships to plant physiology. Since the 1940’s both natural and synthetic growth regulators have been used in agriculture and horticulture with increasing incidence to modify crop plants by controlling plant developmental processes, from germination to post harvest preservation. The concentrations, time and method of applications play an important role in determining the effect of these chemicals on varied fruit crops. Plant growth regulators have a great use for nursery growers from storage of planting material to branch initiation. As, quality planting material is a paramount concern of the researchers and fruit grower’s for better growth and yield of plants. Exogenously applied GA3 overcomes seed dormancy in several species and promotes germination in some species that normally require cold stratification, light, or after-ripening. Plant bio-regulators helps in formation of good architecture which will enhance better quality production, better utilization of land and are known to develop higher number of branches, higher leaf area and better ratio between tiny roots and skeletal ones.