Disease resistance plant immunization

The resistance of plants towards disease may well be related to phytoalexin formation, but whatever be the precise function of these compounds, they can only represent one of the complex of factors which operate in disease resistance and immunity. Any protective substances present in the healthy plant must also be important in this connection. A good example of such a substance is provided by our discovery that healthy seedlings of broad bean (Vlcla faba) contain a potent antifungal chemical to which we have given the name Wyerone. 

Enhanced resistance to disease in plants after an initial infection has fascinated observers for over 100 years. A review of the subject by Chester in 1933 contains 201 references (Jj. "Immunization", "acquired systemic resistance", or "induced resistance" of plants have been reviewed in recent years (2-11). We shall not exhaustively review the literature, but shall focus on general principles and phenomena of particular relevance to the use of "plant immunization" for the practical control of disease. This paper will stress examples from our own research program, but wi1i also include literature citations to provide the reader with an appreciation of important research contributions of others previously and presently active in the field. Most examples presented will deal with fungal, bacterial, or viral diseases of crop plants, but similar principles may apply to infestations by nematodes and, possibly, insects. 

Immunization of plants via priming for expression of latent genetic information encoding disease resistance mechanisms may be... 

Immunization of cucumbers by (L lagenarium, C. cucumerinum, P. 1achrymans or TNV generates a systemic increase in peroxidase activities (. TJ, ] 9, 8U) > Like 1 i gni f ic a t ion and phytoalexin induction, peroxidase activities also rise more quickly in response to infection in leaves of immunized plants, even though total activity eventually may be highest in infected susceptible leaves (77). Several other stimuli can induce local (mechanical and chemical injury) or systemic (senescence, ethylene) peroxidase increases that are not accompanied by increased disease resistance. Thus, enhanced peroxidase activity per se may not be a defense mechanism, but may be a necessary adjunct with appropriate chemical substrates for processes important in disease resistance, e.g., lignification, suberization, and me 1anization. 

There are two key aspects for a well growing plant. One is external factors including environmental conditions and disease resistance methods the other is the integrated immune system of the plant. The plant immune system consists of two interconnected tiers of receptors, one outside and one inside the cell. Both systems perceive the invaders, then inform the whole plant and sometimes the neighboring plants that the intruder is present by an optional signal. The two systems belong to different classes of plant receptor proteins that detect different types of pathogen molecules. ... 

ABA is another important plant hormone that participates in plant diseases and stress resistance (Mauch-Mani and Mauch 2005). The role of ABA in CTS-induced plant immunity was studied by Iriti and Faoro (2008). Chitosan application induced ABA accumulation in leaf tissues at 24 h after treatment, and elicited resistance against TNV. Besides, treatment with nordihydroguaiaretic acid (an ABA inhibitor) before chitosan application reduced tobacco resistance to the necrosis virus. It is indicated that ABA plays an important role in CTS-induced resistance mechanism. 

KIM, j.-s. HEO, M.-s. (2009) Effect of plant active compounds on immune response and disease resistance in Cirrhina mrigala infected with fungal fish pathogen, Aphanomyces invadans. Aquaculture Research, 40,1170-1181. 

Certain cultivars, or varieties, of plants have been bred for their resistance to some pests and diseases. None is completely immune, but nonetheless, some resistance can be invaluable, especially where the threat from a particular pest, disease, or virus is high. 

Lower leaves yellow, wilt, and die. Cause Fusarium wilt. Other symptoms of this common fungal disease include yellowing and wilting of 1 side of plant only drooping flower heads stunted mature plants dark brown areas on stems and partial or total root decay. Once introduced on diseased plants or transmitted by wind, water, or handling, Fusarium wilt lives on indefinitely in soil. There is no cure. Remove infected plants and dispose of them in sealed containers in household trash. Never plant China asters in the same location 2 years in a row. Wilt-resistant cultivars are available, but they are not completely immune. 

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