Plant Physiology - Musiyenko M.M. 2001

Introduction
Subject and tasks of plant physiology, main areas of modern phytophysiology

Modern plant physiology is an integrative discipline that investigates the core vital Functions of plant organisms across various Levels of biological Organization. The Subject Matter of plant physiology encompasses the functions of living plant organisms, their Organs, Tissues, Cells, and cellular components, as well as the underlying causes of their various physiological manifestations. The methodology of plant physiology is grounded in METABOLISM/2.html">THE CONCEPT OF the plant Organism as a complex, self-regulating system comprising a hierarchy of structural levels—ranging from subcellular macromolecules to the whole plant. The comprehension of physiological functions is achieved by examining simpler Levels of organization, followed by the integration of data when analyzing physiological systems of increasing complexity.

The ultimate goal of plant physiology is to understand the patterns governing plant life functions, uncover their mechanisms, develop a conceptual framework for the Structural and functional organization of plant systems at various levels, and formulate ways to regulate the plant organism.

Living systems, including plant organisms, exhibit a higher form of integrity, an inseparable connection, and a mutual interdependence of their constituent components. One manifestation of this integrity is that, despite the immense importance of each individual function, the vital activity of the organism as a whole depends on how a specific function relates to others, and how these relationships are coordinated with changing environmental conditions.

The exceptional Specificity of Chemical Composition and morphological Structure, the tight correlation between Structure and function, the dependence of metabolic processes on structural states, and the dynamic Nature of the latter—these are the defining Properties of the subject of research in plant physiology.

The problems and tasks of plant physiology are so broad and complex that solving them requires a comprehensive set of sophisticated Physicochemical Methods, alongside diverse experimental and theoretical approaches. This is precisely why this discipline ranks among the exact fundamental sciences.

An important aspect of plant physiology is the practical orientation of its research, which justifies its well-established status as the theoretical foundation for rational crop production and modern biotechnology. The advancement of Introduction/32.html">Genetic Engineering METHODS opens up new possibilities for engineering plants with novel, practically valuable traits. Plant physiology undoubtedly holds a prominent position within The system of biological knowledge. As part of the botanical discipline cluster, plant physiology is closely linked with biochemistry, biophysics, immunology, genetics, and mathematical modeling, and maintains the closest ties with animal physiology. After all, if plants and animals—like all living things—share a common evolutionary ROOT, then all living matter must possess certain shared traits, such as Respiration, Nutrition, irritability, and self-reproduction, among others. In this regard, we will continuously strive to emphasize general biological patterns and explore the interconnections between individual physiological phenomena wherever possible.

To understand plant life, one must first analyze all individual manifestations of its vital activity, studying in detail the Physical and Chemical phenomena that underlie these life processes. This is accomplished through the analytical method of research. However, having understood the individual constituent parts, the physiologist must reconstruct the picture of the plant organism's activity as a unified whole. Therefore, the analytical method must be followed by the synthetic method. Applying this method requires accounting for the specific course of various life processes in different particular plant species and cultivars, as well as their dependence on environmental conditions.

The Implementation of the synthetic method, alongside general physiology, has led to The Emergence of the physiology of individual crops and applied physiology. However, for synthesis (whether experimental or logical), a physiologist cannot rely solely on the analysis of life phenomena; they must also understand the evolutionary history of organisms. Therefore, alongside the experimental comparative method, the physiologist must employ the historical method as a complementary tool.

As is well known, the evolutionary theory explains the perfection and adaptiveness of organic forms. Consequently, we are currently witnessing a strengthening of ties with evolutionary biology and the emergence of a promising subfield—evolutionary physiology. It examines The Development of adaptive responses in ontogeny under changing environmental conditions, as well as the historical development of ontogeny itself, encompassing functions, structures, overall metabolism, and its specific pathways within the plant. In other words, studying functional adaptations in both ontogeny and phylogeny is the primary overarching task of evolutionary physiology.

As K.A. Timiryazev emphasized, plant physiology studies the transformation of matter, energy, and form in plants. However, today—with the general theory of complex system regulation successfully developing and much clarified regarding the self-regulation of plant organisms—The Study of information transformation should be added to this triad. This is because all the features and potentials of a plant that take shape during GROWTH AND DEVELOPMENT are actualized by the genetic apparatus only through the assimilation of matter, energy, and information from the environment. The environment itself acts as a factor that facilitates The conversion of The Genome's potential into the specific processes of ontogeny. Herein lies the dialectical unity between the information contained within The Cell genome and that received from the outside.

When studying plant vital activity across all levels of organization (molecular, subcellular, cellular, tissue, organ, organismal, species, population, and biocenotic), we must remember that plant physiology is fundamentally based on the dialectical unity and interconnection of structure and function.

With the achievement of a sufficient depth of knowledge regarding the structural and functional organization of intracellular processes, a prerequisite has emerged to shift the primary focus of plant physiologists toward the realm of supracellular, tissue, and organ organization of physiological phenomena, and to decode the complex mechanisms integrating elementary cellular processes up to the level of whole-organism physiological responses. The spatial and temporal coordination of a vast array of potential reactions underlies the plant's capacity for self-regulation, self-preservation, and self-reproduction.

Thus, the efforts of plant physiologists should be directed toward solving two cardinal problems of general biological significance: the plant organism as a system, and the plant as an element of a broader system (biogeocenosis). The development of these novel approaches has brought plant physiology closer than ever to addressing challenges related to establishing fundamentally new crop production technologies.

In the near future, biology will face a series of challenges that demand fundamental research in the field of plant physiology. Alongside fundamental investigations at the subcellular and molecular levels, paramount importance at The current stage is acquired by the problems of uncovering the mechanisms of self-regulation and integration that ensure the integrity of the plant organism, its environmental resilience, and its high ultimate productivity.

We have all experienced the rising resource and energetic costs required to produce a unit of plant biomass. Another doubling of crop yields requires a 20- to 30-fold increase in resource and energy expenditures. Plant physiology now faces The Challenge of developing resource-efficient plant organisms, including through the Genetic Transformation of their photosynthetic apparatus, immune system, and nitrogen-fixation systems.

The intensification of crop production and the development of Ukraine's agricultural sector are becoming leading drivers of negative impacts on the biosphere, causing chemical, biogenic, and genetic environmental pollution. Therefore, it is necessary to find ecologically safe systems and technologies based on the study of advanced plant pharmacology and biochemistry. On this basis, we must develop diverse plant growth regulators, fertilizers, and new-generation anti-stress preparations—and above all, learn to manage the plants' own endogenous regulatory systems while avoiding the application of external (exogenous) chemical regulators.

A true revolution is underway in The Doctrine of Plant Growth and Development. Phytohormonology raises the question of the possibility of managing plant ontogenetic processes by creating compounds through targeted synthesis that influence growth responses. Understanding the Endogenous mechanisms of hormonal regulation holds not only theoretical but also profound practical significance, which is closely tied to solving problems of productivity and plant stress resistance.

Current yield increases are accompanied by a decline in product quality (such as reduced protein content in wheat, lower sugar content in sugar beet roots, and increased pesticide and herbicide contamination in crop yields). Therefore, we must develop the physiological foundations for managing crop quality through the optimization and balancing of root nutrition, growth, Photosynthesis, and the accumulation of economically valuable products, including secondary metabolites.

One of the most promising research avenues remains The problem of the phototrophic function of plant organisms as the basis for the primary transformation of solar energy and the maintenance of ecological equilibrium in the biosphere.

According to data from the latest International Congress on Photosynthesis (Budapest, 1998), the most critical problem of the coming millennium is the accumulation of carbon dioxide in the atmosphere, driven both by the massive consumption of fossil fuels and by the decomposition and oxidation of organic remains. The amount of atmospheric CO₂ is partially self-regulated, but it cannot be ruled out that this process might trigger unforeseen climate changes. Now that the physicochemical foundations of photosynthesis are known, scientists are focusing primarily On the Relationship between photosynthesis and plant productivity—specifically, the possibility of altering or modifying photosynthetic reactions to create artificial systems for harnessing solar energy. Therefore, in the near future, we should expect major breakthroughs in managing photosynthetic functions both in conventional crop production and in the creation of entirely novel biotechnological processes based on controlled photoautotrophic biosyntheses.

At present, as natural ecosystems are catastrophically disrupted by anthropogenic stress, Ecological and Physiological studies—including those on wild plant species—are acquiring substantial theoretical and practical significance. Compared to artificial ecosystems (agrophytocenoses), the physiology of plants in natural ecosystems remains poorly understood. At the same time, these ecosystems and their flora exhibit A number of unique features. These include a colossal evolutionary genetic potential, a diversity of adaptation pathways across a wide range of living conditions, and principles of vital process regulation that differ somewhat from those of cultivated crops.

Investigating the human-beneficial traits of specific wild species (such as high resilience, competitiveness, and life strategy types) can open pathways for introducing them into the genotypes of cultivated plants, as well as help select species for ecological restoration, environmental phytodecontamination, and bioindication.

As is well known, out of roughly a quarter of a million existing angiosperm species, only a few hundred hold economic significance, and the number of staple agricultural crops does not exceed a few dozen. Therefore, future research in this direction will allow us to introduce new species both as sources of food and as reservoirs of diverse raw Materials.

In-depth research is required into the physiology of diseased plants, the physiology of fungal pathogens, and the problem of plant-to-plant interactions (allelopathy), including its driving factors and physiological mechanisms.

Finally, we stand on the threshold of disrupting the equilibrium of the Earth's atmosphere. Driven by ever-increasing energy demands, humanity is forced to partake in a dubious experiment, because unlike plants, humans have not learned to directly harness solar energy. The plant organism's solution to this challenge surpasses any technical feats currently known to humanity. The process of photosynthesis inherent in plants continues to hold the secret of how green leaves utilize solar energy to generate food for all life on Earth. Unlocking the true nature of photosynthesis will bring us closer to understanding THE ORIGIN OF life, taming solar energy, artificially synthesizing CARBOHYDRATES, fats, and Proteins, and resolving the global energy crisis.

The future of humanity, the population of which will continue to grow significantly, depends on the further progress of plant physiology and the comprehensive enrichment of knowledge in every subfield of this discipline.

Of course, it is unlikely that all the aforementioned problems can be solved by orthodox plant specialists alone. It requires a joint effort from representatives of various sciences, yet The Role of the plant physiologist must remain pivotal.