Molecular phylogeny, identification and pathogenicity ofRhizopus oryzaeassociated with root rot of mulberry in India

Abstract

Aims Root rot caused by a group of fungi is a serious disease in mulberry. This study aims to identify and characterize Rhizopus oryzae and other fungal species associated with root rot of mulberry in India. Methods and Results Rotted root samples were collected from the mulberry gardens from four states of Southern India. The majority of the isolates identified were R. oryzae, and others were saprophytic fungi, less abundant to occasional. Two methods of inoculations were tested to confirm the pathogenicity of the selected isolates and R. oryzae was found to be pathogenic on susceptible mulberry genotypes RC2 and SRDC‐1. Multi gene phylogenetic analyses using the internal transcribed spacer region (ITS), actin (ACT) and translation elongation factor 1‐α (TEF), identified the isolates as R. oryzae. Additionally, Ovatospora brasiliensis, Amesia nigricolor, Gongronella butleri, Myrmecridium schulzeri, Scedosporium boydii, Graphium euwallacea, Clonostachys rosea andTalaromyces spp. were also identified. Conclusion This study revealed the existence of eleven species of fungi including the first report of R. oryzae and the occurrence of weak pathogens or saprophytes that are associated with the root rot of mulberry in India. Significance and Impact of the Study This is the first report of R. oryzae causing Rhizopus rot of mulberry in India. Moreover, the occurrence of saprophytes associated with root rot of mulberry was identified. Further studies should focus more on the ability of these species to generate secondary metabolites and extracellular lytic enzymes as they are beneficial for the management of root rot disease.

Characterization and Pathogenicity of Lasiodiplodia theobromae Causing Black Root Rot and Identification of Novel Sources of Resistance in Mulberry Collections

“…The mycelial mats were separated by using sterilized filter paper (Whatmann No.1). DNA extraction was performed, following the method described by Gnanesh et al (2021).…”

“…Karnataka, Andhra Pradesh, West Bengal and Tamil Nadu are the major silk producing states in India (Central Silk Board, 2020). The tropical climate of South India is highly favorable for mulberry cultivation where the crop is harvested at every 70 days (Gnanesh et al, 2021). Mulberry production is limited by several diseases as the perennial nature of the mulberry provides scope for long-term survival and multiplication of soil-borne pathogens (Sharma et al, 2003).…”

“…In mulberry, different kinds of root rot have been reported, such as black root rot, dry root rot, charcoal root rot, violet root rot, white root rot, Armillaria root rot, Rhizopus rot, and bacterial root rot (Gnanesh et al, 2021;Radhakrishnan et al, 1995;Sharma et al, 2003;Yoshida et al, 2001). Amongst them, black root rot (BRR) caused by Lasiodiplodia theobromae (syn.…”

Exploration of Soil and Weather Factors on Mulberry Root Rot Incidence in the Western Zone of Tamil Nadu, India

“…Soil-borne pathogens such as Macrophomina phaseolina, Lasiodiplodia theobromae, different species of Fusarium, Helicobasidium mompa, Rhizopus oryzae, Helicobasidium mompa, Rosellinia necatrix, Armilaria mellea have been reported as causal agents of root rot in mulberry [5,11,17,18,19]. In addition, many saprobes/ weak pathogens including Aspergillus sp, Ovatospora sp, Talaromyces sp, Amesia sp, Gongronella sp, Myrmecridium sp, Clonostachys sp were associated with mulberry root rot [20].…”

Molecular Characterization of Mulberry Root-Knot Nematode, Caused by Meloidogyne incognita using Modified DNA Isolation Protocol

“…The RKN causes leaf yield loss up to 20% in addition to deterioration of leaf quality and severity increases with age of the garden (Arunakumar et al, 2021). Association of root-knot nematode with root rot disease caused by various fungal pathogens form a root disease complex (Gnanesh et al, 2020).…”