Comparative Analysis Delineates the Transcriptional Resistance Mechanisms for Pod Borer Resistance in the Pigeonpea Wild Relative Cajanus scarabaeoides (L.) Thouars

Abstract

Insect pests pose a serious threat to global food production. Pod borer (Helicoverpa armigera (Hübner)) is one of the most destructive pests of leguminous crops. The use of host resistance has been an effective, environmentally friendly and sustainable approach for controlling several agricultural pests. The exploitation of natural variations in crop wild relatives could yield pest-resistant crop varieties. In this study, we used a high-throughput transcriptome profiling approach to investigate the defense mechanisms of susceptible cultivated and tolerant wild pigeonpea genotypes against H. armigera infestation. The wild genotype displayed elevated pest-induced gene expression, including the enhanced induction of phytohormone and calcium/calmodulin signaling, transcription factors, plant volatiles and secondary metabolite genes compared to the cultivated control. The biosynthetic and regulatory processes associated with flavonoids, terpenes and glucosinolate secondary metabolites showed higher accumulations in the wild genotype, suggesting the existence of distinct tolerance mechanisms. This study provides insights into the molecular mechanisms underlying insect resistance in the wild pigeonpea genotype. This information highlights the indispensable role of crop wild relatives as a source of crucial genetic resources that could be important in devising strategies for crop improvement with enhanced pest resistance.

Comparative TMT Proteomic Analysis Unveils Unique Insights into Helicoverpa armigera (Hübner) Resistance in Cajanus scarabaeoides (L.) Thouars

“…Eynck et al [ 36 ], Costa et al [ 37 ], and Lauvergent et al [ 38 ], also reported higher accumulation of monolignol enzymes in tolerant/resistant cultivars. This study is also consistent with the transcriptomic studies of Njaci et al [ 19 ], where there was greater induction of CHS, an important flavonoid enzyme, in the wild, tolerant C. scarabaeoides accession in response to H. armigera infestation than in the susceptible variety, ICPL 87. Rathinam et al [ 39 ], reported a similar observation in the wild pigeonpea, C. platycarpus , with accession having more proteins involved in the phenylpropanoid pathway and flavonoid biosynthesis when compared to a cultivated pigeonpea genotype.…”

“…Also, at the vegetative stage the plant has the greatest responses to various stresses [ 18 ]. A similar pattern of high accumulation of proteins in the wild pigeonpea and clustering of the replicates to their respective species is consistent with previous studies by Njaci et al [ 19 ] and Rathinam et al [ 20 ].…”

“…Carbohydrate metabolism provides essential energy for plant survival and defence, while amino acids metabolism is involved in biosynthesis of precursors important for secondary metabolites synthesis. Numerous studies, such as those by Njaci et al [ 19 ], Rathinam et al [ 21 ], Zhou et al [ 22 ] and Rojas et al [ 23 ], have observed that plants mobilise and prioritise metabolomic pathways to produce chemical compounds involved in defence. These include toxic and deterrent compounds, attraction of predator enemies, signalling and triggering an array of physiological responses like ROS generation, systemically acquired response redox homeostasis, and the reconfiguration of primary metabolites compromising growth and reproduction.…”

Simple, Fast and Efficient Methods for Analysing the Structural, Ultrastructural and Cellular Components of the Cell Wall

“…Cellular responses to climate change, improved biofuel production, and enhanced crop productivity can be measured using these techniques [ 6 , 8 ]. This enables the development of better strategies and promotes our understanding of growth and development dynamics, for example, the allocation of energy during the formation of different tissues, vegetable crop, pest resistance, reproductive rate, and structural components in the cell wall, as well as during biosynthesis [ 9 , 10 , 11 , 12 ].…”

Plant Cell and Organism Development 2.0

“…The article by Njaci et al [8] concerns a high-throughput transcriptome profiling approach for studying the defence mechanisms in a susceptible genotype of the important legume crop Cajanus cajan (pigeonpea) against Helicoverpa armigera (pod borer) and in its wild relative (C. scarabaeoides), which is resistant to this insect pest. The authors identified the key genes, signalling pathways and metabolites that are utilised by C. scarabaeoides in its defence against a pod borer infestation.…”