Erwinia carotovora ssp. carotovora Infection Induced “Defense Lignin” Accumulation and Lignin Biosynthetic Gene Expression in Chinese Cabbage (Brassica rapa L. ssp. pekinensis)

Abstract

Erwinia carotovora subsp. carotovora (Ecc) infects and causes soft rot disease in hundreds of crop species including vegetables, flowers and fruits. Lignin biosynthesis has been implicated in defensive reactions to injury and pathogen infection in plants. In this work, variations of lignin content and gene expression in the molecular interaction between Chinese cabbage and Ecc were investigated. H 2 O 2 accumulation and peroxidase activity were detected by 3, 3 -Dimethoxybenzidine staining at mocked and Ecc-inoculated sites of Chinese cabbage leafstalks. Klason lignin contentin inoculated plants increased by about 7.84%, 40.37%, and 43.13% more than that of the mocked site at 12, 24 and 72 h after inoculation, respectively. Gas chromatography detected more p-coumaryl (H) and less coniferyl (G) and sinapyl (S) monolignins in leafstalks of Chinese cabbage. All three monomers increased in Ecc-infected leafstalks, and the Ecc-induced "defense lignin" were composed of more G and H monolignins, and less S monolignin. After searching the expressed sequence tags (EST) data of Chinese cabbage, 12 genes putatively encoding enzymes involved in lignin biosynthesis were selected to study their expression. All of these genes could be induced by mock inoculation and Ecc infection, while the gene expression lasted for several more hours in the infected samples than in mocked and untreated plants. Our results indicated that "defense lignin" was different from the developmental lignin in composition; G and S monolignins were significantly induced in plants in response to the soft rot Ecc; thus, lignin biosynthesis was differentially regulated and played a role in plant response to the soft rot Ecc.

Trichoderma mediate early and enhanced lignifications in chickpea during Fusarium oxysporum f. sp. ciceris infection

“…Previous studies showed that the structural lignin is different from the defense lignin . In the present study, lesser plant mortality in the plants where the positive correlation was seen between higher expression of the selected genes and higher lignifications may therefore be attributed to contribution of both structural and defense lignin.…”

Occurrence of guaiacyl/p-hydroxyphenyl lignin in Arabidopsis thaliana T87 cells

“…pekinensis) also accumulated a lignin composed of more guaiacyl and p-hydroxyphenyl units when infected by a soft rot fungus, Erwinia carotovora subsp. carotovora (Zhang et al 2007). On the other hand, wheat (Triticum aestivum), a monocotyledonous plant, produced syringyl-rich, but not p-hydroxyphenyl, lignin in response to a stem rust fungus (Puccinia graminis f. sp.…”

Abiotic and Biotic Stresses and Changes in the Lignin Content and Composition in Plants

“…An analysis of an EST database of Chinese cabbage identified 12 genes putatively encoding enzymes involved in lignin biosynthesis, which were selected for expression studies. All of these genes were induced in infected and mocked plants, but their expression lasted more hours in the infected samples than in mocked and untreated plants, suggesting their involvement in a defense mechanism mediated by lignin (Zhang et al 2007).…”