LECTURE 1: INTRODUCTION TO PLANT ECOPHYSIOLOGY

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1 Password: LECTURE 1: INTRODUCTION TO PLANT ECOPHYSIOLOGY We all need people who will give us feedback. That's how we improve. Bill Gates LECTURE OUTCOME After the completion of this lecture and mastering the lecture materials, students should be able to 1. explain the meaning of plant ecophysiology, synecology and autecology 2. describe the development of ecophysiology as a scientific discipline 3. explain the role of genetic and environmental factors in ecophysiology 4. explain stress response, acclimation response, and adaptation 5. explain some phenomena of ecophysiology 1

2 LECTURE FLOW BRAIN EXERCISES 1. INTRODUCTION Definition Other Terms History of Ecophysiology Application of Ecophysiology TYPES OF PLANT RESPONSES ECOPHYSIOLOGY STUDIES BRAIN EXCERCISE How do plants cope with excess light when it is very cold? How do plants cope with soils deficient in phosphorus? How do plants cope with excessive salt? How do plants manage to grow in deep shade? What mechanisms enable a barley variety cope better with manganese deficiency than other variety? Why so few plant species in one place? 2

3 What is plant ecophysiology? Study of physiological responses to the environment, or study of how the environment affects the function of plants Interface between ecology and physiology: -Ecology provides the questions -Physiology provides the tools 1. how do plants cope with excess light when it is very cold? e.g. avoid the morning sun 3

4 2. how do plants cope with soils deficient in phosphorus? e.g. grow cluster roots 3. how do plants cope with excessive salt? e.g. sequester salt in salt bladders 4

5 4. how do plants manage to grow in deep shade? e.g. use light flecks 5. What mechanisms enable a barley variety on the left cope better with manganese deficiency than other variety on the right? 5

6 6. Why so few plant species in one place? Filters Some species do not occur in the UK, because they were never introduced Others arrived, but never made it to maturity Some evolved locally, or were introduced and made it Filters are constantly changing/interacting 1. INTRODUCTION 1. Definition 1. The growth, reproduction, and geographical distribution of plants are profoundly influenced by their physiological ecology. 2. The physiological ecology is the study of physiological responses to the environment which is the interface between ecology and physiology. Ecology is the study of the interaction of plants and animals with their environment. 6

7 Physiology is concerned with the functions of living things from the level of atoms and small molecules to that of the whole organism 3. The term of physiological ecology is also known as Environmental Physiology, Ecological Physiology and Ecophysiology. 4. Ecophysiology is defined as well as the study of physiological responses of plants to environment (Lambers et al.1998) the study of plant functions in response to environment to gain answers to the problems of plant ecology through understanding plant functions. the science of understanding the physiological (and structural) strategies that allow a plant to live where it lives What is the environment? Physical Environment (light intensity, temperature, gravity, etc.) Chemical Environment (H2O, CO2, O2, N2, minerals, toxins, etc.) Biotic Environment (soil organisms, competition for space and other resources, herbivory, allelopathy, etc.) 7

8 5. Physiological ecologists are concerned with understanding controls on where plants grow how so many species can survive in different habitats, and how so many species can coexist in these habitats DEFINITION 6. The aim of plant Ecophysiology is to provide casual mechanistic explanations for ecological questions that relate to SURVIVAL, DISTRIBUTION, ABUNDANCE & INTERACTIONS OF PLANTS WITH OTHER ORGNISMS 7. Why a particular species live where it does? How does it manage to grow there successfully? Why is it absent from other environments? Ecophysiological study yields information which is fundamental for an understanding of the mechanisms underlying adaptive strategies 8

9 2. Other Terms 1. Synecology, a term that has been long utilized by the plant ecologist as that part of his science, is concerned with the interactions of plants with each other. 2. Autecology is concerned with the response of individual plants to their environment. 3. Autecology is, then, essentially equivalent to ecophysiology, but ecophysiology is not concerned only with the responses of individual plants, but may also be concerned with the several functions of several plants making up a plant community. 3. History of Ecophysiology Ernst Stahl ( ) who introduced experimentation to ecological research may be considered as the founder of ecophysiology. The term of ecology was introduced by Ernst Haeckel and defined in 1866 as The entire science of the relations of the organism to its surrounding environment comprising, in a broader sense, all conditions of its existence. The earliest study of physiological responses of plants to the environment was contributed by Andreas Franz Wilhelm Schimper ( ) who studies Morphological Features of Presumed Adaptive Value 9

10 4. 5. A.F.W. Schimper, who was widely travelled in the tropics including Java in , is best known for plant geography on an ecological basis (Pflanzengeographie auf Physiologischer Grundlage), published in Jena in 1898 in which he coined the term tropical rainforest. He also recognized the need for physiological experimentation: the oecology of plantdistribution will succeed in opening new paths on condition only that it leans closely on experimental physiology, for it presupposes accurate knowledge of the conditions of the life of plants which experiment alone can bestow 4. Application of Plant Ecophysiology 1. Understanding the limits on agricultural production 2. Natural resource management 3. Environmental Science 10

11 2. TYPES OF PLANT RESPONSE Types of Response Time Scales is the intermediate detrimental effect of a stress on a plant process (seconds to days) ACCLIMATION Time scale of physiological response is important in determining how a plant copes with changes in the environment e.g. short- and long-term changes in temperature STRESS RESPONSE Stress response Acclimation response Adaptation/evolution response is the morphological and physiological adjustment by individual plants to compensate for the decline in performance following exposure to stress (days to weeks) ADAPTATION is the evolutionary response that results from genetic changes in populations leading to morphological and physiological compensation for the decline in performance caused by stress 11

12 Stress and acclimation (of an individual) vs. adaptation (a long-term genetic response) Stress response Illustration of the response of plants to water stress. Stomatal response, ROS scavenging, metabolic changes, and photosynthesis are all affected when plants are subjected to water stress. These collective responses lead to an adjustment in the growth rate of plants as an adaptive response for survival. Source: Osakabe et al. (2014) 12

13 Stress response Genes Abiotic stress can enhance the expression of specific transcription factors (TFs) like C-repeat Binding Factors (CBF), No Apical meristem ATAF and Cup-Shaped Cotyledon (NAC), MYB mediated by abscisic acid (ABA). Source: Rejeb et al. (2014) Acclimation Model of action of priming agents during the acclimation of plants to abiotic stress conditions. Source: Filippou et al. (2013). MAPKs: Mitogen-activated protein kinases 13

14 Induced acclimation theoretically involves the induction of defense-related genes/proteins and antioxidants ultimately leading to a specific cellular status, the so-called primed state. Environmental stimuli are effectively perceived and sensed in primed plants through a complex crosstalk that involves various signaling compounds, such as MAPKs, phytohormones, and Ca2+ 3. ECOPHYSIOLOGY STUDIES An overall goal of studies in ecophysiology is to understand and describe where and how plants grow from the standpoint of physiological process. Therefore plant ecophysiology is related to the study of physiological processes in response to the environmental factors; Water Light Temperature Nutrients Nutrients CO2 O2 Salinity etc. 14

15 1. General Optimum narrow range of environmental conditions to which an organism is best suited Gen. The physiological processes of plants are controlled by genes that are expressed differentially with time under the influence of environment factors that change with time 15

16 Species Distribution. The interaction between genetic and environmental factors that changes with time may explain the following questions. - Why do plants grow where they do?, and Why can't all species grow everywhere? Bhattarai, K.R* and Vetaas, O.R Response to Water 1. Incense-cedar (Calocedrus, coniferous trees) Family: Cupressaceae Genus: Calocedrus 2. Douglas-fir (Pseudotsuga menziesii, evergreen coniferous trees) Family: Pinaceae Genus: Pseudotsuga 3. Madrone (Arbutus) Family: Ericaceae Genus: Arbutus 4. Coast redwood (S. sempervirens) Family: Cupressaceae Genus: Sequoia 5. California bay (U. californica) Family: Lauraceae Genus: Umbellularia 6. Big-leaf Maple (A. macrophyllum), Family: Sapindaceae Genus: Acer 16

17 Water where plants grow Reduction in soil stomata close Species differ in tolerance to drying soils 17

18 3. Response to Light 18

19 Soybean CER in Malang What does this picture mean to you 19

20 4. Response to Nitrogen Maximum growth rate of a plant reflects N availability in its natural habitat. A. stolonifera occurs on more nitrogen-rich soils than A. canina. Leaf N & Photosynthesis 20

21 Evergreen leaves Plants adapted to nutrient-poor conditions tend to have evergreen leaves 5. Response to Salinity Organisms in variable environments adjust their solute levels based on the salinity of the water. 21

22 Marine fish are hypo-osmotic compared to seawater, gain solutes and lose water. Solutions are constant drinking and secreting salt into the water Sharks and rays have high concentrations of solutes in their blood, making them iso-osmotic compared to seawater. To maintain proper concentrations of ions, sharks keep urea in the bloodstream. Each organism has an optimum environment Local optimum: 22

23 6. Response to Temperature Why does temperature matter? Temperature: Oxygen consumption The average adult at rest inhales and exhales something like 7 or 8 liters of air per minute or about 11,000 liters of air in a day. The air inhaled is about 20% O2 (oxygen), and that exhaled is about 15% O2, so about 5% of the volume of air is consumed in each breath and converted to carbon dioxide. Therefore, a human being uses about 550 liters of pure O2 per day or 22.9 liters/hour. 23

24 Oxygen and altitude Temperature: Enzyme characteristics 24

25 Endothermy vs ectothermy An Endotherm is an organism that produces heat through internal means (e.g muscle shivering, metabolism activity An Ectotherm is an organism that relies on environmental heat sources which permits them to operate at very economical metabolic rates Temperature: Lower body temperature Endothermy requires a lot of energy Alternative is torpor which is a state of decreased physiological activity in an animal, usually characterized by a reduced body temperature and rate of metabolism during a portion of the day (usually night) to conserve energy 25

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