Genetic Diversity, Identification, and Utilization of Novel Genetic Resources for Resistance to Meloidogyne incognita in Mulberry (Morus spp.)

Abstract

Mulberry (Morus spp.) is an important crop in the sericulture industry as the leaves constitute the primary feed for the silkworm. The availability of diverse genetic sources of resistance to root- knot nematode (RKN; Meloidogyne spp.) are very scanty and therefore, a set of 415 varied exotic and indigenous germplasm accessions were screened under glasshouse conditions. Twenty one accessions were identified as highly resistant and 48 were resistant, the highest numbers of highly resistant/resistant accessions were found in Morus alba. Further, thirty accessions based on rooting ability were evaluated for field resistance at four different locations with infested soil. Finally, eight germplasm accessions; BR-8, Karanjtoli-1, Hosur-C8, Nagalur Estate, Tippu, Calabresa, Thai Pecah and SRDC-3 were identified as potential genetic sources in RKN resistance breeding programs or as resistant rootstock for the establishment of mulberry gardens. Sixteen SSR markers analyzed among the 77 resistant and susceptible accessions, generated 55 alleles, ranging from 2 to 5 with an average of 3.43 alleles per locus. Principle coordinate analysis grouped the accessions on the basis of RKN susceptible and resistant to a greater extent. The RKN susceptible accessions exhibited higher variability as compared to resistant accessions and they were more dispersed. Analysis of molecular variance showed that maximum molecular variance (78%) within the population and 22% between populations. Results of this study indicate that SSR markers are reliable for assessing genetic variability among the RKN resistant and susceptible mulberry accessions.

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.…”

“…Biocontrol measures were not very effective due to the influence of various factors on their efficacy (Nelson, 2004). Genetic improvement by breeding a resistant variety ensures a cost-effective and environment-friendly system for the control of plant diseases (Arunakumar et al, 2021;Pandey et al, 2021). Identification and breeding of resistant mulberry varieties is the only justifiable option to achieve sustainable mulberry cultivation.…”

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

“…Out of these two species, M. incognita is very serious and persistent to the mulberry (Govindaiah et al, 1991;Arunakumar et al, 2021). The severity and damage depends on soil and climatic conditions of different locality (Ramkrishnan and Senthilkumar, 2003).…”

“…The severity and damage depends on soil and climatic conditions of different locality (Ramkrishnan and Senthilkumar, 2003). The disease is widespread and common in sandy soils under irrigated condition (Arunakumar et al, 2018). M. incognita is more dangerous to mulberry by severe damage to the crop and also it predisposes the plant to other soil-borne pathogens (Bhagyrathy et al, 2000;Sukumar et al, 2000;Nishitha Naik et al, 2003).…”

“…Infected plants lose their ability to absorb moisture and nutrients results in reduced metabolic function which leads to deterioration in leaf quality and effects on silk worm health and quality of cocoon production (Rani and Kumari, 2017). 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).…”