Australasian Plant Pathology (2021) 50, 621-630

Kunal Mandal, A. Anil Kumar and D. Ghosh (2021)
Development of screening techniques to evaluate response of jute (Corchorus olitorius) to Macrophomina phaseolina
Australasian Plant Pathology 50 (5), 621-630
Abstract: Thirteen jute genotypes were evaluated for resistance against Macrophomina phaseolina (Mp) in the sick plot, and six of them were identified for stable differential disease reactions. We tested whether other screening methods could produce similar results in these host genotypes. An incubation temperature of 35 °C was optimum for Mp sclerotia germination (90.8%), and it was chosen for experiments involving sclerotia as inoculum. Infestation with 250 or more Mp sclerotia/g seed induced morbidity in ~ 40% seedlings in vitro. Inoculation at the root and leaf could not differentiate between susceptible (JRO 524) and resistant (JRO 204) cultivars. Infesting both growth media and seed with Mp sclerotia induced early (15 days post-inoculation, DPI) expression of disease symptoms. However, the host reactions were in great variation with those from the field screening. Mp inoculum consisting of growing mycelial tips was more aggressive producing 6.4 cm long stem lesion at 4 DPI as compared to 3.9 cm by 7-day-old inoculum. Inoculating at the middle of the main stem produced the largest lesion (5.7 cm long) compared to the basal (3.3 cm) and the tip (1.3 cm) inoculations 6 DPI. Plants at > 70 days after sowing (DAS) produced larger stem lesions than younger plants. This technique grouped test genotypes similar to sick plot experiments, with minor variations. Stem inoculation method may be adopted for large-scale screening and also confirming the resistance reaction of jute towards Mp infection.
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Research topic(s) for pests/diseases/weeds:
resistance/tolerance/defence of host

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Macrophomina phaseolina	Jute (Corchorus)	India