<div style="text-align: justify;">Plants are affected by an extensive range of microbes, such as fungi, bacteria, viruses, viroids, and protozoa. Over the advancement, plants have evolved to defend against pathogens by developing numerous defense mechanisms in the plant cell that respond to chemical and physical barriers, These are present in plants locally or integrally. Plants have an unacquired immunity system to battle against pathogens, such as microbe-associated molecular patterns (MAMPs) are recognized through pattern recognition receptors in a primitive immune system which intermediates the defense response. Pattern recognition receptors (PRRs) they play a major role in plant innate immune system. They encode host sensors of PRRs, they can able to detect molecules of the pathogens such as macrophages, dendritic cells, neutrophils and epithelial cells containing proteins that are present in plant immune system. In this system, they identify two classes of molecules such as pathogen-associated molecular patterns (PAMPs), which are conjoined with microbe associated molecular patterns (MAMPS), and damage-associated molecular patterns (DAMPs). These are correlated with host cells released during cell damage or cell death, these are evolved before adaptive immunity. These extracellular receptors of Pattern Recognition Receptors were first identified in plants and many plant PRRs have been identified by using genomic analysis (rice and Arabidopsis). There are six classes of R-proteins, playing the major role of plant innate immunity which help to activate a defense mechanism from different microbes. Many of plant R genes encode proteins which are nucleotide-binding site and leucine-rich repeats (NB-LRR) region that contact with pathogen effectors to cause defense responses. Pathogen infection in plants is usually limited by an accomplished defense response activated by resistance genes.</div>

Role of resistant-proteins in plant innate immunity- A review

<div style="text-align: justify;">Hypersensitivity is a natural defense for plants in response to a variety of pathogens such as viruses, bacteria, fungi and is characterized by a programmed cell death (PCD) accompanied by an accumulation of toxic compounds within the dead cell. Hypersensitive response (HR) is considered a biochemical reaction rather than a structural defense mechanism but can be seen with the naked eye or with a microscope. There are two types of hypersensitive responses: structural and induced. PCD is seen in both structural as well as in induced hypersensitive response. PCD is extreme resistance shown by the plants in which it kills its cells (suicidal death), upon a perception of the pathogen to deprive it of nutritional supply and stops its growth. Cell death plays a central role in innate immune responses in both plants and animals. Apoptosis and autophagy are physiological processes and two forms of biochemical PCD. Induced hypersensitive response comes out when the plant recognizes specific pathogen-produced signal molecules known as elicitors. Recognition of elicitors by the host plants activates an army of biochemical reactions. These reactions include an oxidative burst of reactive oxygen species (ROS), alterations in plant cell wall also including cell wall immunity (CWI) and damage-associated molecular patterns (DAMPs), induction of phytoalexins and synthesis of PR proteins. These all, are comprised under the first line of defense of plants which come into action after recognition of conserved molecules characteristic of many microbes. These are called elicitors and are known as microbeassociated or pathogen-associated molecular patterns (MAMPs or PAMPs). The second line of defense of plants is the recognition of effectors through plant resistance gene products known as R genes, which result in effector-triggered immunity (ETI). This is supported by the gene for gene hypothesis. Avirulence gene encodes a protein which is specifically recognized by genotypes of the host plant harboring the matching resistance genes.</div>

Hypersensitive Responses in Plants

<div style="text-align: justify;">Environment is an important aspect of plant ecology and global environmental change is of major concern that is caused by natural and human activities which alter greenhouse gas concentrations in the atmosphere. The increase in concentration of greenhouse gases is foreseen to continue to raise average global temperature. Elevated concentration of carbon dioxide with increased temperature influences the plant-disease interactions. The environment has an influence over the development as well as temporal and spatial dissemination of plant diseases. The result of change in environment can either be favorable, non favorable or impartial, as these changes can either lessen, expand or have no influence on diseases as each disease may be attributed differently to these variations in accordance to an area or time of year. Variation in environmental conditions is said to be influencing plants in natural ecosystems all around the world and change in climate directly impacts crops, along with their synergy in accordance with the microbial population. The important elements governing magnification and spread of plant diseases are temperature, moisture, light and carbon dioxide concentration. Environment change causes a significant impact on germination, reproduction, sporulation, spore dispersal, along with perforation by pathogens as a vulnerable host will not be invaded by a pernicious pathogen if the environmental conditions are not facilitative for disease. The environment influences all life stages of host as well as that of a pathogen and as a result induces an opposition to various pathosystems. Resistance mechanisms of plants, including effector-triggered immunity (ETI), pattern-triggered immunity (PTI) and defence network of hormones, are particularly influenced by environmental elements. Pathogenic virulence mechanisms like fabrication of virulence proteins and toxins, and also spore germination and survival are governed by factors such as atmospheric carbon dioxide, temperature and humidity. A large number of <em>in-vitro </em>experiments to understand interactions between plants and pathogens rely on predetermined pathosystems by making use of ascertained environmental conditions which take into consideration relatively small part of vital plant&ndash;pathogen&ndash;environment interactions occurring in natural ecosystem. Thus, there is a need to research effectiveness of disease management strategies that is, to assess current management strategies to understand multifaceted nature of environment-pathogen interactions for production of crops that are irrepressible to environment change.</div>

Role of resistant-proteins in plant innate immunity- A review

Hypersensitive Responses in Plants

Environment-Pathogen Interaction in Plant Diseases