Evaluation of mulberry germplasm for resistance to powdery mildew in the field and greenhouse

Abstract

Powdery mildew caused by the ascomycete Phyllactinia guttata (syn. P. corylea) is a major foliar disease worldwide of the unique mulberry (Morus spp.) for silkworm feed. Genetic resistance to powdery mildew, the most sustainable and economical strategy for disease control, is still elusive for tropical mulberry. About 147 germplasm sources, representing 18 countries of origin, were screened for resistance to P. guttata in six seasonal fields and greenhouse trials after exposure to natural and artificial inoculum, respectively. In the field, the level of plant responsiveness to disease was assessed from 30 to 62 days after pruning in each season as variations in the disease severity index (DSI), disease incidence (DI%) and area under the disease progress curve (AUDPC). These measures differed significantly among the germplasm. Of 147 germplasm sources, *6.8% had useful resistance (two high and nine moderately resistant) to the powdery mildew pathogen on the basis of DSI. The AUDPC values were 13.5-fold higher in the most susceptible accession-(Philippines) than the least responsive (Vietnam-2). The results of DSI were strongly correlated with the obtained DI values (r = 0.92; P \ 0.01) and AU-DPC (r = 0.89; P \ 0.01). Moreover, field screening results were highly correlated (R 2 = 0.839) with values from the greenhouse evaluation using artificial inoculum. However, the DSI values in field and greenhouse screenings for three sources (Non-nayapati, Nao-khurkul and Tista Valley) varied significantly. A relatively low disease reaction of 09 resources (Vietnam-2, Ankara and 07 others) using different assessment scales after natural and artificial inoculation prove, for the first time, that they have potential in breeding for resistance in tropical mulberry to powdery mildew.

Direct Foliar Application of dsRNA Derived From the Full-Length Gene of NSs of Groundnut Bud Necrosis Virus Limits Virus Accumulation and Symptom Expression

“…Considering these possibilities, in the present study, dsNSs was applied on the leaves a day before (T1), immediately (T2), and a day after (T3) the challenge-inoculation of plants with GBNV. The analysis of disease progress showed lower DSI and AUDPC in dsRNAtreated plants of both cowpea and N. benthamiana and a strong positive correlation was established between DSI and AUDPSC values, which indicated a good covenant between the two parameters of disease measurement (Roy et al, 2009 andChattopadhyay et al, 2010).…”

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

“…Screening of mulberry germplasm using pathogenic L. theobromae isolates, and identification of highly durable BRR resistant varieties can aid in achieving sustainable sericulture. Mulberry researchers in India have identified resistant accessions to bacterial leaf spot (Xanthomonas campestris), powdery mildew (Phyllactinia corylea), charcoal root rot (M. phaseolina), and root knot (Arunakumar et al, 2021;Banerjee et al, 2009;Chattopadhyay et al, 2010;Maji, 2011;Pinto et al, 2018). To our knowledge, there is no report on screening of germplasm resistance against L. theobromae causing BRR.…”

Association of leaf micro-morphological characters with powdery mildew resistance in field-grown mulberry (Morus spp.) germplasm

“…In a recent screening programme of 147 individuals of various Morus species, 6 % of the germplasm showed powdery mildew resistance under both natural and artificial epiphytotics ( Chattopadhyay et al . 2010 ).…”