تأثير مكرزة جذور نوعين معمرين من نبات الأجرد Helianthemum almeriense (L.)‎ Mill. و Helianthemum violaceum (L.)‎ Mill. بفطر الكمأة الصحراوية Terfezia claveryi في وقايتهما من بعض الممرضات الفطرية

الملخص EN

This study was conducted in the laboratories of the National Commission for Biotechnology (NCBT), Damascus, Syria, during 2016-2017.

Samples of wild rockrose plant and desert truffle were collected from Damascus countryside.

The desert truffle samples were identified at the species level, and the fungi in the rhizosphere were isolated, purified, identified, and then tested for their pathogenicity on one month old plantlets, micro-propagated in vitro, of two species of desert truffles plant hosts H.

almeriense and H.

violaceum.

The effect of the fungi was then tested on plants of these two species, acclimatized in pots and inoculated with the mycorrhizae fungus Terfezia claveryi.

One month after inoculation, the following parameters were measured: leaves’ surface area, plant length, number of leaves, and disease symptoms on plants or plantlets.

Results revealed that the isolated fungi were: Fusarium sp., F.

roseum, F.

equisti, F.

oxysporum, and Rhizoctonia sp.

The species H.

almeriense showed high susceptibility to F.

equisti as the following symptoms were observed: top necrosis, damping off from top to bottom accompanied with leaf dryness, partial leaf drop, with final death of all plantlets.

In addition, there was a sharp decrease in the leaves’ surface area, plantlets’ length and leaves’ number (297.3 mm2, 70.7 mm, 28 leaves, respectively) compared to the control (1204 mm2,135.8 mm, 38.5 leaves, respectively).

H.

violaceum plantlets showed high susceptibility to F.

roseum as they produced the above mentioned symptoms.

In addition, there was a sharp decrease in the leaves’ surface area, plantlets’ length, and leaves’ number (370.7 mm2,65.2 mm, 44.5 leaves, respectively) compared to the control (718 mm2, 86.5 mm, 49 leaves, respectively).

The rest of fungal pathogens showed different pathogenicity levels on both Helianthemum species which varied from aggressive to nonpathogenic.

The fungus Fusarium sp., was nonpathogenic on both Helianthemum species.

On the other hand, the mycorrhized plants with the truffle fungus Terfezia claveryi, were in excellent health conditions one month after inoculation with the studied pathogenic fungi and showed no disease symptoms.

The decrease in plant’s length, leaves’ surface area, and leaves’ number was small and insignificant compared to that in the control for each of the two studied rockrose species, and for each of the studied pathogenic fungi.

This study demonstrated the clear and significant effect of symbiosis between the two species of rockrose plants: H.

almeriense and H.

violaceum with the fungus Terfezia claveryi which led to a mycorrhiza induced resistance against the following pathogenic fungi: Fusarium sp., F.

roseum, F.

equisti, F.

oxysporum and Rhizoctonia sp., which infect these plants root system.

Key words: Desert truffle, Terfezia claveryi, rockrose, symbiosis, Helianthemum almeriense, Helianthemum violaceum, Fusarium sp., Fusarium roseum, Fusarium equisti, Fusarium oxysporum, Rhizoctonia sp.