دور الميكوريزا في استحثاث مقاومة البندورة الطماطم إزاء الفطر Pythium ultimum من خلال تنشيط إفراز هرمون ميثيل الجاسمونيك

Abstract EN

This research aimed to study the impact of arbuscular mycorrhizal fungi (AM) in reducing damping-off disease in tomato through activation of methyl jasmonic hormone responsible for induced systemic resistance (ISR) in the plant.

Eight isolates of the causal organism were purified and identified based on morphological and molecular characteristics.

Results revealed that all the isolates were P.

ultimum.

Mycorrhizae isolates were characterized according to the international classification and confirmed by the Plant Protection Research Institute in Tehran (Iran).

Six mycorrhizal fungal species of the genus Glomus were determined.

Inoculum mixture of the six isolated mycorhiza species was prepared at a concentration of 127 spores/10 g inoculum, using pot culture protocol.

The experiment was conducted under greenhouse conditions with five treatments: (P): Pythium, (M): mycorrhizae, (M+P): Pythium and mycorrhizae at seeding time, (PM): Pythium then adding Mycorrhizae two weeks later, and (MP): mycorrhizae them adding Pythium, two weeks later, in addition to a control treatment (C).

Mycorrhizal fungi showed high efficiency in reducing P.

ultimum incidence and development in tomato seedlings.

Disease severity was significantly reduced by 73.59% in (MP) treatment and by 30.02% in P+M compared with the positive control.

Methyl jasmonic hormone activity was estimated by using high performance liquid chromatography (HPLC).

Results revealed significant increase in the concentration of the methyl jasmonic hormone and the peroxides enzyme in plant seedlings coexist with mycorrhizal fungi alone or in the treatment with mycorrhizae followed by Pythium.

Methyl jasmonic concentration increased 35 days after the M treatment to 3.25 ng/g, and to 5.90 ng/g after MP treatment compared with the 1.36 ng / g in the M+P treatment.