Prohexadione‐Ca induces resistance to fireblight and other diseases¹

Abstract

Prohexadione-Ca is primarily used for the control of shoot growth in pome and other fruit trees. During its development, treated apple and pear trees were found to be significantly less affected by fireblight ( Erwinia amylovora ) and other pathogens, although prohexadione-Ca is inactive as a bactericide or fungicide. Prohexadione is a structural mimic of 2-oxoglutaric acid, and the distinct dioxygenases involved in gibberellin biosynthesis that require this compound as a cosubstrate are blocked. As a result, less growth-active gibberellins are formed and treated plants remain compact. 2-Oxoglutaric acid-dependent dioxygenases are also involved in flavonoid metabolism. In shoots of apples and pears, prohexadione-Ca causes considerable changes in the formation of flavonoids and their phenolic precursors by inhibiting flavanone 3-hydroxylase. Convincing evidence is available that prohexadione-Ca triggers pathogen resistance primarily by inducing the formation of 3-deoxyflavonoids, in particular luteoforol, with phytoalexin-like properties. Morphoregulatory effects caused by prohexadione-Ca are only of secondary relevance. The simultaneous control of excessive shoot growth and shoot infections by fireblight is seen as a major advantage of using prohexadione-Ca in pome fruit trees.

Evaluation of host resistance inducers and conventional products for fire blight management in loquat and quince

“…A suppression of disease incidence was not associated with substantial growth control on pears (Buban et al 2002), which was comparable to the results on loquat and quince in this study. These results indicate that the effects of prohexadione-Ca on the incidence of fire blight are primarily the result of physiological changes (Rademacher 2004). In addition, Unrath (1999) pointed out that varied results were obtained with prohexadione-Ca in climatically different regions.…”

Advances in the Valorization of Lignocellulosic Materials by Biotechnology: An Overview

“…Recent reports show that a biological-based approach has potential for improving both the economics and the environmental impact of the pulp generation. Bio-pulping can be defined as the biological pre-treatment using white rot fungus to metabolize the lignin in wood, freeing up the fibers so that they can be used for paper production (Rademacher 2004;Habibi et al 2008;Tuncer et al 2009;Singh et al 2010;Fu et al 2012) (Fig. 5).…”

Determination of application time for chemical control of fire blight disease in pear varieties

“…Prohexadione-Ca is a plant growth regulator that is used to control the vegetative growth of especially apple and pear trees (Evans et al 1997;Evans et al 1999). Prohexadione-Ca has been shown not only to suppress apple shoot growth but also to reduce the incidence of secondary shoot blight infections (Breth et al 1999;Bastas & Maden 2004) and suppress the extension of lesions (Beyers & Yoders 1997;Rademacher 2004).…”