Perspectives on the utilization of resistance mechanisms from host and nonhost plants for durable protection ofBrassicacrops against Alternaria blight

Abstract

Background Alternaria brassicae, the causal organism of Alternaria blight, is a necrotroph infecting crops of the Brassicaceae family at all growth stages. To circumvent this problem, several disease management strategies are being used in the field, and disease-resistant varieties have also been developed. However, no strategy has proven completely successful, owing to the high variability in virulence among A. brassicae isolates, which causes a diverse spectrum of symptoms. Nonhost resistance (NHR) is a robust and broad-spectrum defense mechanism available in plants, and the exploitation of gene pools from plant species that are nonhost to A. brassicae could serve as novel sources of resistance. Methodology We searched the literature using key words relevant to this study in various search engines, such as PubMed, Web of Science, and Google Scholar, as well as certain journal websites. The literature was retrieved, sorted, and mined to extract data pertinent to the present review. Results In this review, we have comprehensively covered the recent progress made in developing Alternaria blight resistance in Brassica crops by exploiting host germplasm. We also enumerate the potential NHR sources available for A. brassicae and the NHR layers possibly operating against this pathogen. In addition, we propose different strategies for identifying NHR-related genes from nonhost plants and testing their relevance in imparting broad-spectrum resistance when transferred to host plants. Conclusion This review will help broaden the current knowledge base pertaining to the resistance sources available in host germplasm, the exploitation of NHR mechanisms, and their applications in protecting Brassica crops from Alternaria blight. The insights might also be applicable to a wider repertoire of plant pathogens.

Acuities into tolerance mechanisms via different bioassay during Brassicaceae-Alternaria brassicicola interaction and its impact on yield

“…The genus Brassica consists of members rich in nutritional and economical values [ 2 ]. In spite of substantial crop production in oilseed Brassica , immense inconsistency remains between actual and potential yield due to exposure to various stresses (biotic/abiotic) [ 3 ]. Alternaria fungi are well-known among biotic stresses for their damaging behavior [ 4 ].…”

Current Status of the Disease-Resistant Gene(s)/QTLs, and Strategies for Improvement in Brassica juncea

“…The related wild species of B. juncea was reported to possess genes conferring resistance against Alternaria blight disease that can be used for resistance breeding programs ( Fatima et al, 2019 ). The advanced biotechnological approaches such as tissue culture and genome transformation have also been used for developing resistant Brassica lines.…”

Epidemiology, Genetics and Resistance of Alternaria Blight in Oilseed Brassica

“…Therefore, utilizing the non-host resistance from wild species can be an efficient breeding tool. Plant pathogens manage to affect different species, but they fail to overcome the non-host resistance [64]. Examples of some non-host plants of A. brassicae are chickpea, lentil, wheat, sugarcane, barley, tomato, potato [64].…”

“…Plant pathogens manage to affect different species, but they fail to overcome the non-host resistance [64]. Examples of some non-host plants of A. brassicae are chickpea, lentil, wheat, sugarcane, barley, tomato, potato [64]. NHR is multilayered and can be splitted into two main forms: the layer of preinvasion and the phase of post-invasion [65][66][67].…”

“…Despite an accurate germination, pathogens might fail to reach the stomata. Stomata in non-host plants may not be correctly recognized by the pathogen because the topography of the surface may vary significantly from that of the host leaf [64]. Another structural feature that can prevent the entry of Alternaria is the epicuticular wax [72 -74].…”