ABSTRACT
Agrobacterium tumefaciens causes crown gall disease. Although Agrobacterium can be popularly used for genetic engineering, the influence of aboveground insect infestation on Agrobacterium induced gall formation has not been investigated. Nicotiana benthamiana leaves were exposed to a sucking insect (whitefly) infestation and benzothiadiazole (BTH) for 7 d, and these exposed plants were inoculated with a tumorigenic Agrobacterium strain. We evaluated, both in planta and in vitro, how whitefly infestation affects crown gall disease. Whitefly-infested plants exhibited at least a two-fold reduction in gall formation on both stem and crown root. Silencing of isochorismate synthase 1 (ICS1), required for salicylic acid (SA) synthesis, compromised gall formation indicating an involvement of SA in whitefly-derived plant defence against Agrobacterium. Endogenous SA content was augmented in whitefly-infested plants upon Agrobacterium inoculation. In addition, SA concentration was three times higher in root exudates from whitefly-infested plants. As a consequence, Agrobacterium-mediated transformation of roots of whitefly-infested plants was clearly inhibited when compared to control plants. These results suggest that aboveground whitefly infestation elicits systemic defence responses throughout the plant. Our findings provide new insights into insect-mediated leaf-root intra-communication and a framework to understand interactions between three organisms: whitefly, N. benthamiana and Agrobacterium.
Subject(s)
Agrobacterium tumefaciens/physiology , Hemiptera/physiology , Nicotiana/microbiology , Nicotiana/parasitology , Transformation, Genetic , Animals , Cyclopentanes/metabolism , Gene Expression Regulation, Plant , Gene Silencing , Genes, Plant , Models, Biological , Molecular Sequence Data , Oxylipins/metabolism , Plant Exudates/metabolism , Plant Roots/metabolism , Plant Stems/microbiology , Plant Tumors/microbiology , Plant Tumors/parasitology , Plant Viruses/physiology , Salicylic Acid/metabolism , Nicotiana/geneticsABSTRACT
We tried to investigate the expression rate of human papillomavirus (HPV) L1 capsid protein in uterine cervical specimens and correlate it with the grade of dysplasia, HPV genotype and age of the patients. Among uterine cervical specimens proved to have HPV by DNA genotyping test, eighty cytology-biopsy matched cases and 22 unmatched cytology specimens were selected. Immunostaining for L1 capsid protein was performed on both cervical smears and tissue sections. The L1 capsid protein was expressed mainly in the nuclei, but occasionally in the cytoplasm of cells located in the superficial layer of squamous epithelium. The immunostaining for L1 capsid protein showed positive reaction in 47 cases (46.1%) of cervical smears and in 10 cases (12.5%) of tissue sections (P = 0.001). Cytologic diagnosis revealed a higher expression rate in LSILs (25/33; 75.8%) than in HSILs and cervical cancers (8/20; 40.0% and 2/5; 40%, respectively) (P = 0.006). In LSILs, cases with low-risk type HPV showed a higher L1 capsid expression rate than those with the high-risk type HPV (88.9% vs. 70.8%). The L1 capsid expression rate decreased in the over-40-year-old age group compared to the younger age (49.2% vs. 50.8%). Cytology smears were superior to tissue sections for the detection of L1 capsid protein expression. LSILs and HPV low-risk group showed higher L1 capsid expression rate than HSILs and HPV high-risk group, which suggests that L1 capsid expression might be related to a favorable disease biology.
