Search

The effect of sunflower rust (Puccinia helianthi) infection on intercellular β-1,3-glucanase (EC 3.2.1.39) and chitinase (EC 3.2.1.14) activities, phenylalanine ammonia-lyase (EC 3.4.1.5) activity and total salicylic acid content was investigated in relation to disease development in resistant (PhRR3) and susceptible (S37-388) sunflower plants (Helianthus annuus L.). The effect of benzothiadiazole (BTH) treatment on intercellular β-1,3-glucanase activity and disease severity in susceptible plants was also investigated. Rust infection selectively induced increased activity of the pathogenesis-related proteins, β-1,3-glucanase and chitinase, as well as phenylalanine ammonia-lyase activity and total salicylic acid content in the resistant plants. There was an associated increase in the number of aborted substomatal vesicles as well as host cell necrosis in resistant plants. Treatment of susceptible plants with BTH, a functional analogue of salicylic acid, induced intercellular β-1,3-glucanase activity and reduced the susceptibility to rust. [ABSTRACT FROM AUTHOR]

The prostaglandins and brassinosteroids were discovered as regulators of plant growth in the 1970s; all are implicated in various physiological processes including signalling. We examine the history, occurrence, biosynthesis and physiological roles of these compounds. [ABSTRACT FROM AUTHOR]

Provides information on a study which reported the purification of a Russian wheat aphid-induced apoplastic β-1,3-glucanase. Materials and methods; Results and discussion.

The putative flowering stimulus ('florigen') is discussed in relation to the possible involvement of prostaglandins in the flowering of the short-day plant Pharbitis nil. The postulated existence of 'florigen' is based on grafting experiments in the main, but it has been confounded by the failure to isolate a chemical which results in long-day or short-day plants that flower under non-inductive conditions. Prostaglandins play a possible role in the flowering of P. nil.A hypothetical model is presented of the interaction of a gibberellin with prostaglandin F[sub 2 alpha] in the plasma membrane of the leaf, and the subsequent activation of cyclic-AMP in the cytosol, with the further result that a cascade of reactions is initiated. The product(s) of the cascade could be the transmissible stimulus from the leaf to the apex of the plant. This trigger could be extended on short days; during long days, a low molecular weight phenolic acid (such as salicylic acid) could be an inhibitor of prostaglandin biosynthesis in the leaf and thus of flowering [ABSTRACT FROM AUTHOR]