Defensive mechanisms in Plants: The role of component plant cells in defense against biotic and abitic stresses
Abstract
Plants are often exposed to various environmental stresses such as extreme temperatures, drought, and disease and pest attack. In natural systems, plants face a plethora of antagonists and thus posses a myriad of defense and have evolved multiple defense mechanisms by which they are able to cope with various kinds of biotic and abiotic stresses. In fact plants defense against stresses by different ways. The role of cellular organelles is very important in this way. Cell wall and their derivatives such as oligosaccharins as biochemical defenser or for example trichomes as mechanical defenser is the frontline of the plant defense system. Also Plants have evolved a multi-layered immune system that dynamically responds to pathogens alike cell membrane that is a key mediator of communication between plants and microbes. Cytoplasm and the membrane-bounded structures ( organelles) defense against different kind of stresses. The role of cellular organelles in plant defense relate to their enzymes primarily. Enzymes such as proteases, esterases and ribonucleases in cytoplasm, PM H+ - ATPases in plasma membrane or β glucosidases included cyanogenic glucosides, saponins, glucosinolates or DIMBOA (2,4 - dihydroxy-7-methoxy-1,4-benzoxazin-3-one) glucoside in ER are responsible for plant def ense. Also ROSs plus SA and JA in chloroplast and mitochondria play an important role in immune plant system. In nucleus macromolecules including nucleoporins, importins, and Ran-GTP-related components, are essential to mount an efficient immune response i nresponse to different pathogens. And in Golgi apparatus, peroxysomes and vacuoles, glycosyltransferases, myrosinase and hydrolytic enzymes are liablef or plant defense respectively.
Keywords
Download Options
Introduction
Despite of enormous differences in living organisms, all of them have similar characteristics. These similar characteristics that are signs of living organisms are known by us since primary school, respiration, nutrition, reproduction but among living organisms, plants have a very special characteristic that is photosynthesis. Briefly photosynthesis is a process used by plants to convert light energy into chemical energy that can later be released to fuel the organisms' activities ( energy transformation ). Also Photosynthesis is largely responsible for producing and maintaining the oxygen content of the Earth's atmosphere, and supplies all of the organic compounds and most of the energy necessary for life on Earth (Bryant and Frigaard 2006). It is noticeable that in nature algae a nd cyanobacteria, are photoautotroph also. But plants are important means of livelihood and production of human beings . So the relations between plants and human beings are also very close (Anant etal., 2013). Thought to be the importance of plants well i nformed by this short preface till now.
Like all of living organisms plants are continuously subjected to stresses. Stresses in plants are classified by different fo rm but all of stresses are abiotic or biotic generally. An abiotic stress can be a mechanical injury. But biotic stresses in plants refer to plant diseases or phyto-pathogens (Doughari 2015). Plant diseases refer to any disturbance in functioning and growth that cause a lower operating efficiency or a breakdown in the plant’s metabolism. Diseases afflict plants generally result from microbial infections, invasions of the body by pathogenic viruses, bacteria, fungi, or other microorganisms (Dickison 2000). Pests are biotic stresses and are often included insects. Furthermore nematode worms can sicken plants. According to statement plants must campaign against these devastating agents. In this review different defensive mechanisms for survival are noticed in plants. Also in this review the classification of different defensive mechanism will base on defense by cellular and subcellular components.
Conclusion
Photosynthesis is one of the most important processes that occur in green plants, alges and prokaryotic living organisms named cyanobacteria. In this pivotal process sunlight turn into chemical energy (food). In fact life on earth depends on this important process that the highest percentage of it’s occurring in green plants. Briefly only plants can produce food for animals and humans. These supporter li ving organisms are sessile but they have to suffer from an extensive range of biotic or abiotic stresses. So they must equipped against injurious agents. Plants, unlike animals, which have specialized defender cells and an adaptive immune system, have an innate immunity of each cell and produce systemic signals emanating from the infection site. Generally plants campaign against harmful factorsw ith different forms. Sometimes a plant is in contact with a pathogen to which is not a host, this form of defense is the most common form of resistance in nature, sometimes the host can to hinder the growth and/or the development of the pathogen. But this is important that Plant defense systems against pathogen invasion consist of multiple layers that means all of plant cell component such as: cell wall, plasma membrane, cytoplasm, endoplasmic reticulum, chloroplast, mitochondria, Golgi apparatus, peroxysomes and vacuoles.
