Topic
Phytoalexin
About: Phytoalexin is a research topic. Over the lifetime, 1161 publications have been published within this topic receiving 63405 citations. The topic is also known as: phytoalexins.
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TL;DR: The results indicate that the 6a-hydroxylase is specifically involved in the biosynthesis of glyceollin.
Abstract: A microsomal preparation from elicitor-challenged soybean cell suspension cultures catalyzes an NADPH-dependent and dioxygen-dependent 6a-hydroxylation of 3,9-dihydroxypterocarpan to 3,6a,9-trihydroxypterocarpan. The latter is a precursor for the soybean phytoalexin glyceollin. No reaction is observed with NADH. The 6a-hydroxylase is inhibited by cytochrome c.
Optical rotatory dispersion spectra of the enzymatic product formed from racemic dihydroxypterocarpan and of the remaining unreacted substrate proved that the product has the natural (6aS, 11aS)-configuration and that hydroxylation proceeds with retention of configuration.
The 6a-hydroxylase was also found in elicitor-challenged soybean seedlings. The results indicate that the 6a-hydroxylase is specifically involved in the biosynthesis of glyceollin.
73 citations
TL;DR: It was found that the relative expression levels of reactive oxygen species of transgenic soybean plants were significantly lower than those of non-transgenic plants after incubation with P. sojae, suggesting an important role of GmIFR might function as an antioxidant to reduce ROS in soybean.
Abstract: Isoflavone reductase (IFR) is an enzyme involved in the biosynthetic pathway of isoflavonoid phytoalexin in plants. IFRs are unique to the plant kingdom and are considered to have crucial roles in plant response to various biotic and abiotic environmental stresses. Here, we report the characterization of a novel member of the soybean isoflavone reductase gene family GmIFR. Overexpression of GmIFR transgenic soybean exhibited enhanced resistance to Phytophthora sojae. Following stress treatments, GmIFR was significantly induced by P. sojae, ethephon (ET), abscisic acid (placeCityABA), salicylic acid (SA). It is located in the cytoplasm when transiently expressed in soybean protoplasts. The daidzein levels reduced greatly for the seeds of transgenic plants, while the relative content of glyceollins in transgenic plants was significantly higher than that of non-transgenic plants. Furthermore, we found that the relative expression levels of reactive oxygen species (ROS) of transgenic soybean plants were significantly lower than those of non-transgenic plants after incubation with P. sojae, suggesting an important role of GmIFR might function as an antioxidant to reduce ROS in soybean. The enzyme activity assay suggested that GmIFR has isoflavone reductase activity.
73 citations
TL;DR: Fungitoxicity assays demonstrated that the 5-methoxyluteolinidin is a phytoalexin as it prevented germination by, and killed conidia ofColletotrichum sublineolum, the sorghum anthracnose pathogen, at a concentration of 3μ M .
72 citations
TL;DR: The observed structure/activity relationships suggest that these analogues, and the phytoalexins, function primarily as uncouplers of oxidative phosphorylation, which appears to be the main factors affecting the antifungal activity of flavonoids.
72 citations
TL;DR: The level of OsDTC2 mRNA in suspension‐cultured rice cells began to increase 3 h after addition of the elicitor and reached the maximum after 8 h, and it was indicated that stemar‐13‐ene accumulated in the chitin‐elicited suspended‐culture rice cells and the UV‐irradiated rice leaves.
72 citations