First record at molecular level for Rhizoctonia solani causing Rot Root on Aleo vera plants in Iraq

Aloe vera is an important medicinal and cosmetic plant. This study aimed to isolate and diagnose the pathogenic fungi associated with infected Aloe vera in nurseries, Nineveh Province, Northern Iraq in ۲۰۲۰. The results showed the emergence of different pathogenic fungi isolated from the roots, leaves, and stem base (crown area) of Aloe vera. The primary diagnosis based on the morphological characteristics of the fungal colony grown on PDA showed the presence of Rhizoctonia solani with the highest frequency of ۸۲.۵%.  R. solani showed different infection symptoms ranging from yellowing and leaf curling, roots in reddish brown colour, and the infection progresses resulted in appearance of reddish necrotic areas on the crown area. The fungal pathogenicity was confirmed using Koch's postulates. Alternaria alternata ranked second with a frequency rate of ۵۵.۴۵% followed by Fusarium solani with ۴۳.۷۵%. The root rot causing R. solani isolate was confirmed by molecular diagnosis using PCR technique. This is considered to be the first study in Iraq for diagnosing fungi on Aloe vera using PCR with pair of specialized primers Forward FITS ۵′- TCCGTAGGTGAACCTGCGG-۳′ and Reverse RITS ۵′- TCCTCCGCTTATTGATATGC-۳′. The results showed that the isolate under study belongs to R. solani with a band size of ۵۵۰ pb, which is the expected size produced by these primers. The results of DNA sequencing of R. solani isolate under study was registered under accession number ۱. MW۷۳۷۶۶۰. Based on the NCBI information, the isolate showed a similarity in the internal cloning region (ITS) with other isolates by ۹۲-۹۹%.

Keywords:

Rhizoctonia solani , Fungi , Rot Root , Aloe vera