What is the meaning of phytoalexins?

What is the meaning of phytoalexins?

Definition of phytoalexin : any of various antimicrobial chemical substances produced by plants to combat infection by a pathogen (such as a fungus)

What is Phytoalexin example?

Gossypol from cotton, casbene from castor bean, and rishitin from plants in the Solanaceae are examples of phytoalexins biosynthesized by the mevalonic acid pathway (Fig. 13.5).

How are phytoalexins synthesized?

Phytoalexins are a group of chemically diverse broad-spectrum antimicrobial compounds synthesized by plants in response to attack from pathogens. A large number of phytoalexins are products of the phenylpropanoid pathway, while others are synthesized through the mevalonic acid pathway and the Trp pathway.

What are PR genes?

Pathogenesis-related (PR) proteins are proteins produced in plants in the event of a pathogen attack. They are induced as part of systemic acquired resistance. Infections activate genes that produce PR proteins. Some of these proteins are antimicrobial, attacking molecules in the cell wall of a bacterium or fungus.

Which of the following are the strong and antimicrobial activity phytoalexins?

The hydroxycoumarin scopoletin (6-methoxy-7-hydroxycoumarin) is the major phytoalexin in tobacco plants. This compound is well known to display antimicrobial properties in vitro [18] and accumulates in tobacco reacting to pathogens and elicitors [19,20].

Which are strong antimicrobial activity phytoalexins?

Phytoalexins are antifungal or antibacterial compounds synthesized in plants under stresses, fungal attack, or elicitor treatment. Glyceollins are a type of isoflavonoid phytoalexins unique to soybeans and synthesized by soy plants under stressed conditions such as fungal infection.

What is the difference between phytoalexin and Phytoanticipins?

Phytoanticipins are defined as defense compounds which are constitutively present, i.e., regardless of the presence of pests or diseases (VanEtten et al., 1994). By contrast, phytoalexins accumulate only upon perception of pests or pathogens (VanEtten et al., 1994) .

Are phytoalexins phenolic compounds?

Although sakuranetin was identified as a phenolic phytoalexin, most rice phytoalexins are diterpenoid compounds, and research efforts have mainly focused on diterpenoid phytoalexins [15,16,17,18,19]. Until very recently, sakuranetin had been considered the only phenolic phytoalexin in rice.

What are Elicitors give examples?

Commonly tested chemical elicitors are salicylic acid, methyl salicylate, benzothiadiazole, benzoic acid, chitosan, and so forth which affect production of phenolic compounds and activation of various defense-related enzymes in plants.

Which of the following is a PR protein?

The better known PR proteins are PR1 proteins (antioomycete and antifungal), PR2 (β-1,3-glucanases), PR3 (chitinases), PR4 proteins (antifungal), PR6 (proteinase inhibitors) (Fig.

What is Phytoanticipin?

The term phytoanticipin was coined by Mansfield and defined in 1994 as “low molecular weight antimicrobial compound present in plants before challenge by microorganisms or produced after infection solely from preexisting constituents” [1].

Who proposed the role of phytoalexins in disease resistance?

The concept of phytoalexins was first introduced over 70 years ago by Müller and Börger [3] after observing that infection of potato tubers with a strain of Phytophthora infestans capable of initiating hypersensitive reactions, significantly inhibited the effect of a subsequent infection with another strain of P.