Effect of physical and biochemical factors on the formation of infective structures Magnaporthe grisea pyriculiarosis causal agent of rice (Oryza sativa)

Abstract

This study was conducted in the Phytopathology Laboratory at Kobe University, Japan, to evaluate the effect of two physical factors (hydrophobic and hydrophilic surfaces) and two chemical factors (Cyclic Adenosine Monophosphate (cAMP) and collagenase) on the adhesion capacity and appressorium formation of Magnaporthe grisea on hydrophobic and hydrophilic surfaces. In this study, the conidial concentration was adjusted to 1x10^4 conidia/milliliter, and Gelbond™ Film plastic was used. The results indicated that on hydrophobic surfaces, 78% of conidia formed appressoria, with this percentage dropping to zero when placed on a hydrophilic surface. However, the addition of cAMP to conidia growing on hydrophilic surfaces restored their ability to produce appressoria up to 69%. When collagenase was applied to the conidial solution after 6 hours of incubation, its adhesion capacity was reduced to 61% compared to the control treatment without collagenase. This reduction was more evident when the conidial solution was incubated for 6 hours along with collagenase, reducing the number of adhered conidia to 97% compared to the control. Collagenase also reduced the severity of M. grisea symptoms in rice seedlings. The formation of infective structures of M. grisea is favored by hydrophobic surfaces and the presence of cAMP, whereas hydrophilic surfaces and collagenase inhibit it.