ABC transporter genes ABC-C6 and ABC-G33 alter plant-microbe-parasite interactions in the rhizosphere.

Plants are master regulators of rhizosphere ecology, secreting a complex mixture of compounds into the soil, collectively termed plant root exudate. Root exudate composition is highly dynamic and functional, mediating economically important interactions between plants and a wide range of soil organisms. Currently we know very little about the molecular basis of root exudate composition, which is a key hurdle to functional exploitation of root exudates for crop improvement. Root expressed transporters modulate exudate composition and could be manipulated to develop beneficial plant root exudate traits. Using Virus Induced Gene silencing (VIGS), we demonstrate that knockdown of two root-expressed ABC transporter genes in tomato cv. Moneymaker, ABC-C6 and ABC-G33, alters the composition of semi-volatile compounds in collected root exudates. Root exudate chemotaxis assays demonstrate that knockdown of each transporter gene triggers the repulsion of economically relevant Meloidogyne and Globodera spp. plant parasitic nematodes, which are attracted to control treatment root exudates. Knockdown of ABC-C6 inhibits egg hatching of Meloidogyne and Globodera spp., relative to controls. Knockdown of ABC-G33 has no impact on egg hatching of Meloidogyne spp. but has a substantial inhibitory impact on egg hatching of G. pallida. ABC-C6 knockdown has no impact on the attraction of the plant pathogen Agrobacterium tumefaciens, or the plant growth promoting Bacillus subtilis, relative to controls. Silencing ABC-G33 induces a statistically significant reduction in attraction of B. subtilis, with no impact on attraction of A. tumefaciens. By inoculating selected differentially exuded compounds into control root exudates, we demonstrate that hexadecaonic acid and pentadecane are biologically relevant parasite repellents. ABC-C6 represents a promising target for breeding or biotechnology intervention strategies as gene knockdown leads to the repulsion of economically important plant parasites and retains attraction of the beneficial rhizobacterium B. subtilis. This study exposes the link between ABC transporters, root exudate composition, and ex planta interactions with agriculturally and economically relevant rhizosphere organisms, paving the way for new approaches to rhizosphere engineering and crop protection.

Ethylene Response Factor (ERF) genes modulate plant root exudate composition and the attraction of plant parasitic nematodes.

Plant root exudates are compositionally diverse, plastic and adaptive. Ethylene signalling influences the attraction of plant parasitic nematodes, presumably through the modulation of root exudate composition. Understanding this pathway could lead to new sources of crop parasite resistance. Here we used Virus-Induced Gene Silencing to knock down the expression of two Ethylene Response Factor (ERF) genes, ERF-E2 and ERF-E3, in tomato. Root exudates were significantly more attractive to the PPNs Meloidogyne incognita and Globodera pallida following knockdown of ERF-E2, which had no impact on the attraction of Meloidogyne javanica. Knockdown of ERF-E3 had no impact on the attraction of Meloidogyne or Globodera spp. Gas Chromatography Mass Spectrometry analysis revealed major changes in root exudate composition relative to controls. However, these changes did not alter the attraction of rhizosphere microbes Bacillus subtilis or Agrobacterium tumefaciens. This study further supports the potential of engineering plant root exudate for parasite control, through the modulation of plant genes.

Transcriptional signatures of invasiveness in Meloidogyne incognita populations from sub-Saharan Africa.

Meloidogyne incognita is an economically important plant parasitic nematode. Here we demonstrate substantial variation in the invasiveness of four M. incognita populations relative to tomato. Infective (J2) stage transcriptomes reveal significant variation in the expression of protein-coding and non-coding RNAs between populations. We identify 33 gene expression markers that correlate with invasiveness, and which map to genes with predicted roles in host finding and invasion, including neuropeptides, ion channels, G Protein-Coupled Receptors, cell wall-degrading enzymes and microRNAs. These data demonstrate a surprising diversity in microRNA complements between populations, and identify gene expression markers for invasiveness of M. incognita, to our knowledge for the first time.

Intraoperative use of FloSeal with adenotonsillectomy to prevent adverse postoperative outcomes in pediatric patients.

OBJECTIVE: The purpose of this study was to compare postoperative complications associated with monopolar dissection adenotonsillectomy, with and without the application of FloSeal at the completion of the procedure. STUDY DESIGN: Retrospective cohort study. SETTING: Tertiary care pediatric hospital. SUBJECTS AND METHODS: This was a retrospective cohort study of 800 cases of adenotonsillectomy. Two cohorts of patients were identified based on whether or not FloSeal was used intraoperatively during the completion of the monopolar dissection adenotonsillectomy. Outcomes that were measured included: (1) age, (2) sex, (3) diagnosis, (4) primary hemorrhage, (5) secondary hemorrhage, (6) return to operating room, and (7) dehydration. All binomial outcomes measured were subjected to chi-square and t tests. RESULTS: Age and gender were similar between the 2 groups. Chronic tonsillitis was the primary indication more often in the control group; this was statistically significant. Primary hemorrhage occurred in 1 subject from each group (0.28%); secondary hemorrhage occurred in 11 subjects from the FloSeal group (3.22%) and 7 from the control group (1.87%). Both outcomes were not statistically different between the 2 groups. Return to operating room showed no statistically significant difference between groups. The need for postoperative admission for dehydration failed to show statistical significance between groups. CONCLUSION: In our experience, the application of FloSeal hemostatic matrix after monopolar adenotonsillectomy demonstrates no additional reduction in postoperative adverse events encountered in the pediatric population. Specifically, our data failed to demonstrate statistically significant reduction of: (1) primary hemorrhage, (2) secondary hemorrhage, (3) return to operating theatre, or (4) dehydration.