Simulated herbivory in chickpea causes rapid changes in defense pathways and hormonal transcription networks of JA/ethylene/GA/auxin within minutes of wounding

Abstract

Chickpea (C. arietinum L.) is an important pulse crop in Asian and African countries that suffers significant yield losses due to attacks by insects like H. armigera. To obtain insights into early responses of chickpea to insect attack, a transcriptomic analysis of chickpea leaves just 20 minutes after simulated herbivory was performed, using oral secretions of H. armigera coupled with mechanical wounding. Expression profiles revealed differential regulation of 8.4% of the total leaf transcriptome with 1334 genes up-regulated and 501 down-regulated upon wounding at log2-fold change (|FC| ≤ −1 and ≥1) and FDR value ≤ 0.05. In silico analysis showed the activation of defenses through up-regulation of genes of the phenylpropanoid pathway, pathogenesis, oxidases and CYTP450 besides differential regulation of kinases, phosphatases and transcription factors of the WRKY, MYB, ERFs, bZIP families. A substantial change in the regulation of hormonal networks was observed with up-regulation of JA and ethylene pathways and suppression of growth associated hormone pathways like GA and auxin within 20 minutes of wounding. Secondary qPCR comparison of selected genes showed that oral secretions often increased differential expression relative to mechanical damage alone. The studies provide new insights into early wound responses in chickpea.

MicroR408 regulates defense response upon wounding in sweet potato

“…Herbivore-induced damage requires repair of the cell wall to prevent pathogen entry (War et al , 2012). Accordingly, most cell wall repair genes have been reported to be up-regulated upon wounding (Pandey et al , 2017). GAUT family genes are critical proteins for the synthesis of homogalacturonan, which is the most abundant pectic polymer in the primary cell wall of plant (Wolf et al , 2009; L. Wang et al , 2013).…”

Glyphosate induced toxicity to chickpea plants and stress alleviation by herbicide tolerant phosphate solubilizing Burkholderia cepacia PSBB1 carrying multifarious plant growth promoting activities

“…Like many traditional PGPR, glyphosate tolerant B. cepacia PSBB1 used as bacterial inoculant in our study also resulted in a significant improvement in the functioning of chickpea which could possibly be due to the synthesis of plant growth regulators (Premachandra et al 2016). Of these, growth regulators, IAA for example, stimulates elongation or division of cells and promotes root growth (Pandey et al 2017). As a result of expanded roots, the plant absorbs more water and minerals (Rijavec and Lapanje 2016) which consequently leads to enhanced growth.…”

A strong early acting wound‐inducible promoter, RbPCD1pro, activates cryIAc expression within minutes of wounding to impart efficient protection against insects

“…The woundinducible maize protease inhibitor mpiC1 promoter when used to express a synthetic cry1Ac toxin in sorghum showed low accumulation of toxic protein only 12 h postwounding (Girijashankar et al, 2005). The rice OsDof1 promoter in contrast, showed wound-inducible GUS expression within minutes of wounding in transgenic Arabidopsis and rice (Park et al, 2014). However, since the GUS histochemical reaction did not include cycloheximide, one cannot rule out GUS expression during the overnight incubation for color development in these studies.…”

“…For instance, one of the first responses upon abiotic and biotic stress signalling is to reduce normal growth processes and divert resources towards fighting the stress. The opposite actions of stress hormones like JA/SA/ ethylene/ABA versus growth hormones like auxin/GA often leads to either suppression of growth pathways during stress or of stress pathways during growth (Groszmann et al, 2015;Machado et al, 2013;Pandey et al, 2017). In such conditions, the presence of a strong constitutive promoter like CaMV35S that continuously synthesizes an insecticidal toxin protein regardless of a plants' needs, may compromise defense or abiotic stress responses by reducing the resources available for fighting these, thereby increasing susceptibility to the stresses.…”

“…Much research has led to isolation of several wound-inducible promoters from different plants. These include the AoPR1 promoter from PR1 gene of Asparagus officinalis (Warner et al, 1993), the mpiC1 promoter from a maize protease inhibitor gene (Cordero et al, 1994), the fib gene promoter from bell paper (Chen et al, 1998), the win3.12 gene promoter from Populus (Hollick and Gordon, 1995;Yevtushenko et al, 2004), the Shpx6b peroxidase promoter from the forage legume, Stylosanthes humilis, (Perera and Jones, 2004), the OsDof1 promoter of rice (Park et al, 2014) and others. A few of these such as AoPR1 and mpiC1 have been used for expression of CryIAc-type proteins or protease inhibitors with varying success (Girijashankar et al, 2005;Gulbitti-Onarici et al, 2009).…”