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Vegetables are rich source of minerals and nutrition. In India, large quantity of vegetables are sold and purchased everyday. Ideal soil for cultivation of vegetables is sandy loam to clay. Moderate acidic and saline soils can also be preferred for vegetable cultivation. Various fungal and bacterial diseases are proved to be a threat for vegetable cultivation. Pathogens manifest their presence by releasing elicitors (mycelium, sclerotia, sporangia, conidia, etc.). The host plant surface bears a receptor which recognizes elicitors. The elicitor receptor interaction results in changes in plasma membrane permeability. Changes in plasma membrane permeability disturb Calcium-Proton influx and Potassium-chloride efflux. Oxidative burt is mediated by these ionic fluxes. Plant defense machinery mainly comprises reactive oxygen species (ROS) such as superoxide, hydrogen peroxide and hydroxyl free radical. During plant defense, reinforcement of cell wall is catalyzed by the 164ROS which further signaled initiation of defense reactions. Large family of protein kinases (PK) carries defense signaling. PK include large number protein family called calmodulin like protein kinases (CDPK). Calcium signaling, mitogen activated protein kinase (MAPK) and ROS production is largely influenced by CDPK. Infection of fungal pathogen to plant enhance respiration, demand of carbon for energy generation, activity of plant growth hormone, namely, auxin, photosynthesis activity, carbohydrate content, etc. Fungal pathogens cause damage to the host by producing host specific toxins (HST) and non host specific toxins (non HST). HST cause damage to specific genotype while non HST does not have any specificity and attack a wide range of the host. Most of HST’s are produced by Cochliobolus sp. and Alternaria sp. Non HST is produced by Pseudomonas sp., Alternaria sp., Cercospora sp., etc. |
