Comparing the defence-related gene expression changes upon root-knot nematode attack in susceptible versus resistant cultivars of rice

Abstract

Rice is one of the major staple food crops in the world and an excellent model system for studying monocotyledonous plants. Diseases caused by nematodes in rice are well documented and among them, root-knot nematode (RKN), Meloidogyne graminicola, causes extensive yield decline. It is therefore necessary to identify novel sources of natural resistance to RKN in rice and to investigate the rice-RKN interaction in detail to understand the basal plant defence mechanisms and nematode manipulation of the host physiology. To this end, six different cultivars of rice were initially screened for RKN infection and development; Pusa 1121 and Vandana were found to be most susceptible and resistant to RKN infection, respectively. In order to investigate the role of major hormoneregulated plant defence pathways in compatible/incompatible rice-RKN interaction, some wellidentified marker genes involved in salicylate/jasmonate/ethylene pathway were evaluated for their differential expression through qRT-PCR. In general, our study shows a remarkable discrepancy in the expression pattern of those genes between compatible and incompatible rice-RKN interaction. As most information on the molecular interplay between plants and nematodes were generated on dicotyledonous plants, the current study will strengthen our basic understanding of plant-nematode interaction in the monocot crops, which will aid in defining future strategies for best plant health measures.Plant-parasitic nematodes (PPNs) have proved to be one of the most difficult to manage and stubborn pest of agricultural crops. PPNs display a wide variety of interactions with their hosts. Most advanced of them are sedentary endoparasites, which induce a specialized feeding cell in the host tissue. These feeding structures are believed to serve as the singular nutrient source for the nematode development and reproduction. A plethora of nematode effector proteins have been identified which interact with the several plant proteins to initiate and maintain the feeding cell and usurps innate host defence 1,2 .Being one of the major staple food crop, and a promising model monocotyledonous plant, rice (Oryza sativa L.) has garnered considerable attention from the nematologists studying the physiological and molecular interaction between rice and PPNs. Root-knot nematode (RKN), Meloidogyne graminicola is emerging as a serious bottleneck in rice-wheat cropping system of Indo-Gangetic plains and is causing substantial yield losses in all the rice growing belts of South-east Asia. The infective second-stage juvenile (J2) penetrates the rice root behind the root tip zone, traverses the vascular tissue and induces a typical feeding cell, known as the giant cell (GC). Cells surrounding the GC are hypertrophied to render the formation of macroscopic hook-like galls on the root system 3-5 .To date, almost all grown O. sativa cultivars tested are known to be susceptible to RKN infection, while the non-cultivated African relatives, O. glaberrima and O. longistaminata are reported to be resista...

Mechanisms of resistance in the rice cultivar Manikpukha to the rice stem nematode Ditylenchus angustus

“…Again similar to the results presented here, Kumari et al . () recorded a greater induction of lignin biosynthesis genes in the roots of a resistant cultivar versus a susceptible cultivar at 2 days after root‐knot nematode inoculation.…”

“…For instance, the JA pathway is of central importance in root defence against the root-knot nematode Meloidogyne graminicola, whereas SA, JA and ET are equally important for defence against the migratory root nematode Hirschmanniella oryzae (Nahar et al, 2012). A gene expression analysis of rice on root-knot nematode infection revealed significant differential expression of wellidentified SA/JA/ET marker genes when comparing susceptible and resistant interactions (Kumari et al, 2016). However, in contrast with root-parasitic nematodes of rice, there is no knowledge concerning the signalling pathways involved in rice defence against foliar nematodes, such as Ditylenchus angustus.…”

Transcriptomic and histological responses of African rice (Oryza glaberrima) to Meloidogyne graminicola provide new insights into root-knot nematode resistance in monocots

“…These data are consistent with the resistance responses registered in other plant-pathogen interactions where a strong and rapid activation of plant defence usually differentiates the resistant genotype from the susceptible. A recent study in susceptible and resistant varieties of rice (O. sativa) showed similar contrasting data in the qPCR expression pattern for a limited set of genes (Kumari et al, 2016). However, only fragmented data have been reported so far in incompatible plantnematode interactions.…”

Plant genotype and temperature impact simultaneous biotic and abiotic stress‐related gene expression in Pythium‐infected plants

“…Of the abiotic stresses, temperature is considered a dominant abiotic stress impeding agriculture productivity (Meena et al , ). Varieties of different resistance/susceptibility show significant differences at both phenotypic and molecular levels when confronted by pathogens (e.g., Ma et al , ; Cregeen et al , ; Kumari et al , ; Tran et al , ). In the current study, while total RGERs were significantly up‐regulated in all tested varieties, it is noteworthy that up‐regulation in moderately resistant Riverina (Nichols et al , ; You et al , ) was significantly different from Seaton Park (susceptible) and Woogenellup (moderately susceptible) at moderate–high temperatures, confirming that genotype is a critical factor that not only affects gene transcripts but also affects the expression of phenotypic characteristics such as root disease, plant size, and growth rate (You and Barbetti, ; ; You et al , ; ).…”