Senescence Signalling and Control in Plants

Maryam Sarwat, Narendra Tuteja

• Publisher: Academic Press
• Year: 2018
• Print ISBN: 9780128131879
• eBook ISBN: 9780128131886
• Topic: Biological Sciences
• Subtopic: Botany
• Index: Biological Sciences

Senescence Signalling and Control in Plants discusses the studies showing the importance of hormone action on developmental senescence. It shows the involvement of various signaling components (such as EIN2, LOX2) and transcription factors (such as oresara1 or ORE1) in controlling hormonal activity during senescence. Further, the involvement of various micro RNAs (miR164, miR319) in regulating leaf senescence are discussed. Through this book, the authors throw light on all the reverse and forward genetic approaches to reveal the role of various other phytohormones regulating plant senescence and the molecular mechanisms involved.Chapters on relevant topics are contributed by experts working in the area, making this a comprehensive treatise designed to provide an in-depth analysis on the subject matter.- Throws light on the involvement of hormones (other than the well- known hormones cytokine and ethylene) in plant senescence- Shows the underlying mechanisms on the hormonal actions during senescence- Exhibits the involvement of microRNAs during this important plant developmental process

Chapter 1

The Physiology and Molecular Biology of Stress-Induced Senescence

Md. Mahadi Hasan*; Iffat-Ara Sharmeen^†; Khalid Rehman Hakeem*; Hesham F. Alharby*; Abdulrahaman S. Hajar* * Department of Biological Sciences, Faculty of science, King Abdulaziz University, Jeddah, Saudi Arabia
^† Department of Biochemistry, School of Life Sciences, Independent University, Dhaka, Bangladesh

Abstract

Senescence, or the loss of the ability to maintain growth and cell division, is a highly regulated physiological mechanism that ultimately leads to death of leaves and other organs of plants. It is a genetically programmed process in which essential cellular functions like photosynthesis are decreased and breakdown of large molecules rapidly increases. However, early senescence is a loss in terms of both yield and grain filling, as it causes leaves to turn yellowish and photosynthesis to decline, as well as losses due to lower shelf life. Leaf senescence conditions responses to abiotic stress in both phenotypic and molecular aspects. Plant aging and various abiotic stresses like drought, salinity, and the presence of toxic heavy metals induce leaf senescence. This process can affect agricultural and economic status worldwide, critically threatening global food production and security. In both leaf senescence and abiotic stresses, a major early response includes the production of reactive oxygen species (ROS). Plants adapt to stresses by decreasing the level of ROS, but also by ensuring antioxidant production. This chapter discusses the mechanisms observed in senescence induced by abiotic environmental stresses. Also, it discusses how senescence specifically plays a role in the survival of field-grown plants under abiotic stress conditions.

Keywords

Drought stress; Senescence; Reactive oxygen species (ROS); Salt stress; Heavy metals

1 Introduction

Stress factors are conditions to which plants are often exposed, which may negatively affect their growth, productivity, and development. Any condition that does not favor a plant’s metabolism, progressive development, and overall growth is considered as stress (Levitt, 2011; Lichtenthaler, 1996; Bray et al., 2000). Stress has two types: biotic and abiotic. Biotic stress is inflicted by other species or organisms, while abiotic stress originates from a harsh environment, such as waterlogging, soil salinity, mineral deficiency, increased or decreased solar radiation, and temperature (Levitt, 2011; Lichtenthaler, 1996; Bray et al., 2000).

Environmental stresses, including extreme temperature, solar radiation conditions, drought, concentration of phytotoxic substances, amount of soil saturated with water, excess salinity, and mineral deficiency in soil, have adverse effects on plant productivity, as well as giving rise to a genetically scheduled phase in cellular life called senescence (Thakur et al., 2016). In this stage, essential cellular activities such as photosynthesis are lost and large molecules are hydrolyzed (Thakur et al., 2016; Fig. 1). Like other genetically programmed mechanisms, senescence is influenced by internal factors, including the age of the plants, reproductive maturation, and concentrations of regulators like hormones and reactive oxygen species (ROS). Together, these factors ensure the occurrence and advancement of leaf senescence (Munné-Bosch et al., 2001). These environmental factors most likely speed up the process of senescence by influencing the cellular process of aging, overall reproductive stage, and hormone concentration. The internal factors may determine the ability of the plant to carry out senescence under stressful conditions (Munné-Bosch et al., 2001). Environmental stresses like water and nutrient scarcity severely affect plant life in ecosystems, particularly causing deficiency of nitrogen (Di Castri, 1981).

Fig. 1 Regulatory pathways of leaf senescence. Abiotic stress factors induce senescence, leading to cell death. (Adapted from Lim, P.O., Kim, H.J., Nam, H.G., 2007. Leaf senescence. Annu. Rev. Plant Biol. 58, 115–136.)

One of the most immediate responses that occur during a cell’s progression into senescence under stressful conditions is the generation of ROS in large amounts, including oxygen free radicals, peroxides, and superoxides (Bhattacharjee, 2005; Hakeem et al., 2012). Thus, it is suggested that ROS plays a central role in the process of senescence under stressful conditions. Lichtenthaler (1996) mentioned that plants could be introduced to short- or long-term effects of stress, stress that can be partially recovered from by repair systems and adaptation, or powerful stress events that can damage or even kill the plants. Plants respond to stresses such as drought could be determined by a combination of factors like genotype, adaptation to stresses previously experienced, growth stage of the plants, and plant parts exposed to stress (Kozlowski and Pallardy, 2001). Thus, such leaf senescence regulation allows a plant to adapt to a stressful environment and progress through its life cycle (Gan and Amasino, 1997; Ono et al., 2001). Studying leaf senescence is vital for understanding how plant development works and its various responses to stress conditions. Because senescence can decrease crop yield, studying it will allow for ways in which senescence can be handled and controlled for agricultural benefit. This chapter focuses on (1) abiotic stress and the concept of plant senescence, (2) the biological importance of senescence induced by abiotic stress, (3) abiotic stress that induces leaf senescence indicated by numerous symptoms, and (4) cellular and metabolic changes regulated by senescence during abiotic stress.

2 Senescence-Associated Genes and Abiotic Stress

Senescence-associated genes (SAGs) regulate processes involved in senescence (Barth et al., 2006) and have an impact on the system of plant tissues. Many genes and transcription factors are involved in senescence and abiotic stress responses in plants (Fig. 2)...

Table of contents

• Cover image
• Title page
• Table of Contents
• Copyright
• Contributors
• Chapter 1: The Physiology and Molecular Biology of Stress-Induced Senescence
• Chapter 2: Abiotic Stress and Plant Senescence
• Chapter 3: Plant Leaf Senescence: Integrating Multiple Environmental and Internal Cues
• Chapter 4: Signal Transduction in Leaf Senescence: An Overview
• Chapter 5: Regulation of Leaf Senescence by Macromolecule Degradation and Hormones
• Chapter 6: The Role of Growth Regulators in Senescence
• Chapter 7: Jasmonic Acid (JA)-Mediated Signaling in Leaf Senescence
• Chapter 8: Polyamine as Signaling Molecules and Leaf Senescence
• Chapter 9: Oxidative Stress and Leaf Senescence: Important Insights
• Chapter 10: Proteolytic Processes During Leaf Senescence
• Chapter 11: Role of Histones During Leaf Senescence
• Chapter 12: Receptor-Like Kinases Control the Development, Stress Response, and Senescence in Plants
• Chapter 13: Flower Senescence: Present Status and Future Aspects
• Chapter 14: Nutrient Remobilization During Senescence
• Chapter 15: Autophagy and Senescence
• Chapter 16: Plant Senescence and Organ Abscission
• Chapter 17: Senescence-Associated Markers
• Chapter 18: Plant Senescence and Agriculture
• Index