Defensive Resistance of Cowpea Vigna unguiculata Control Megalurothrips usitatus Mediated by Jasmonic Acid or Insect Damage

Abstract

Vigna unguiculata is a vital vegetable crop in Southeast Asia, and Megalurothrips usitatus can cause huge damage to this crop. Enhancing the resistance of V. unguiculata against M. usitatus is a promising way to protect this crop; however, there is limited information regarding the mechanism underlying the resistance of V. unguiculata against M. usitatus. Here, a behavior assay was performed to explore the resistance of V. unguiculata against M. usitatus after insect damage or treatment by jasmonic acid (JA). Furthermore, transcriptome and metabonomics analysis was used to detect the putative mechanism underlying the resistance of V. unguiculata against M. usitatus. The pre-treatment of Vigna unguiculata with JA or infestation with Megalurothrips usitatus alleviated the damage resulting from the pest insect. We further identified differentially expressed genes and different metabolites involved in flavonoid biosynthesis and alpha-linolenic acid metabolism. Genes of chalcone reductase and shikimate O-hydroxycinnamoyltransferase involved in flavonoid biosynthesis, as well as lipoxygenase and acyl-CoA oxidase involved in alpha-linolenic acid metabolism, were upregulated in plants after herbivory or JA supplementation. The upregulation of these genes contributed to the high accumulation of metabolites involved in flavonoid biosynthesis and the alpha-linolenic acid metabolism pathway. These transcriptional and metabolite changes are potentially responsible for plant defense and a putative regulatory model is thus proposed to illustrate the cowpea defense mechanism against insect attack. Our study provides candidate targets for the breeding of varieties with resistance to insect herbivory by molecular technology.

Megalurothrips usitatus Directly Causes the Black-Heads and Black-Tail Symptoms of Cowpea along with the Production of Insect-Resistance Flavonoids

“…The increase in ABA may also be induced by water loss resulting from M. usitatus, as ABA is also an indicator of water stress. Li et al [26] have shown that defensive resistance of cowpea control M. usitatus is mediated by JA insect damage. However, there was no significant difference in SA content between treatments.…”

Signal Mediators in the Implementation of Jasmonic Acid’s Protective Effect on Plants under Abiotic Stresses

“…Jasmonic acid (JA) and its derivatives are one of the key groups of “stress” plant hormones [ 3 , 4 , 5 ]. A large body of experimental data has been accumulated showing the action of JA as a regulator of plant growth and development [ 6 , 7 ], as well as signal activating expression of plant defense genes during pathogen infestation [ 8 , 9 ] and plant damage by phytophages [ 10 ]. In recent decades, it has been demonstrated that JA also participates in the adaptive responses of plants to various abiotic factors such as extreme temperatures, drought, salinity, heavy metal ions, and ultraviolet radiation [ 3 , 9 , 11 , 12 , 13 , 14 , 15 ].…”