Stereoselective Physiological Effects of Metconazole on Seed Germination and Seedling Growth of Wheat

Abstract

In addition to their fungicidal activity, many triazole fungicides function as plant regulators, which might impose adverse effects on the growth and development of crops. For chiral triazole fungicides, these effects can be alleviated by applying stereoisomers with high fungicidal and low regulator activities. This study investigated the stereoselectivity of four stereoisomers and the racemate of metconazole (2.5 g/100 kg seeds) on emergence and growth of seedlings (BBCH 01-14) in wheat. Wheat seedlings, coated with cis-1S,5R-metconazole, had a significantly lower seedling emergence ratio and shoot length than other metconazole treatments; however, the opposite effects were observed in the trans-1S,5S-metconazole treatment. With regard to the hormonal level, enzyme activity, and gene transcription of gibberellin (GA) and jasmonic acid (JA), cis-1S,5R-metconazole treatment inhibited GA biosynthesis while trans-1S,5S-metconazole treatment promoted GA biosynthesis. Moreover, cis-1S,5R-metconazole, trans-1S,5Smetconazole, trans-1R,5R-metconazole, and racemate treatments increased JA biosynthesis. The oxidative stress responses in trans-1R,5R-metconazole and racemate treatments were more intensive. Therefore, compared with the control, treatment with cis-1R,5Smetcoanzole exhibited minimal influence on wheat seedling growth. The results showed that the application of pure cis-1R,5Smetcoanzole (instead of the racemate) in agricultural management could decrease the risks associated with crop growth and developmental damage.

Hexaconazole Application Saves the Loss of Grey Mold Disease but Hinders Tomato Fruit Ripening in Healthy Plants

“…As such, HEZ should be used to control but not prevent grey mold disease. HEZ is a triazole fungicide that could repress the biosynthesis of GA . Compared with the control, the GA content at 7 and 10 d was significantly decreased in the HEZ and HEZ+ B.…”

“…For instance, metconazole blocks the GA synthesis in wheat seedlings. 5 Meanwhile, GA promotes fruit growth by enhancing cell expansion. 32 In this study, compared with the control, a decrease in the fruit size and fresh weight were also observed in the treatment with B. cinerea and HEZ+B.…”

“…Total RNA extraction, concentration measurement, and RNA reverse transcription into cDNA were done as previously described. 5 Real-time quantitative polymerase chain reaction was also performed as previously described. 13 The Actin gene was used as the reference gene.…”

“…For example, metconazole treatment disrupted the balance between gibberellin (GA) and jasmonic acid (JA) in wheat seeds which decreased the germination rate of these seeds and the growth of the subsequent seedlings. 5 HEZ promotes morphological changes in plants, such as inducing rooting 6 and regulating plant hormone levels, such as decreasing GA synthesis 7 and increasing abscisic acid (ABA) content. 8 However, the effect of HEZ on tomatoes when applied to prevent and control gray mold disease is still obscure.…”

“…Triazole fungicides modulate the different CYP types; therefore, a lot of research has reported the disruptive effect of triazole fungicide on the secretion of plant hormones. For example, metconazole treatment disrupted the balance between gibberellin (GA) and jasmonic acid (JA) in wheat seeds which decreased the germination rate of these seeds and the growth of the subsequent seedlings . HEZ promotes morphological changes in plants, such as inducing rooting and regulating plant hormone levels, such as decreasing GA synthesis and increasing abscisic acid (ABA) content .…”