doktorska disertacija
Nik Susič (Author), Barbara Gerič Stare (Mentor)

Abstract

Tropske vrste ogorčic koreninskih šišk (RKN) so izredno polifagni škodljivci v kmetijstvu, kjer povzročajo velike izgube pridelka. Nekatere vrste, kot so Meloidogyne ethiopica, M. inornata in M. luci (MEG), je zaradi visoke sorodnosti težavno razlikovati. Sekvencirali smo 7 izolatov ogorčic iz skupine MEG ter po zlaganju zaporedij genomov določili filogenetsko umestitev v rod. Zloženi genom ogorčice M. luci SI-Smartno V13 je s 327 kontigi, N50 dolžini kontigov 1,7 Mb in končni dolžini zloženega zaporedja 209,2 Mb, trenutno najpopolnejši javno dostopen genom RKN. Filogenetska analiza je pokazala na umestitev vseh izolatov iz skupine MEG v enoten monofiletski klad, vrsta M. luci se je bistveno razlikovala od vrst M. ethiopica in M. inornata. Preizkušali smo uporabnost hiperspektralnega slikanja za zgodnje razločevanje biotskega stresa (napad RKN) od abiotskega stresa (suša) pri rastlinah paradižnika. Z analizo hiperspektralnih posnetkov v območju spektra 400-2500 nm je bilo mogoče razlikovati med dobro zalitimi ter sušnimi rastlinami s 100 % natančnostjo, z 90-100 % natančnostjo pa je bilo mogoče razlikovati med zdravimi in napadenimi rastlinami. Ovrednotili smo nematicidno aktivnost in analizirali genoma bakterij Bacillus firmus I-1582 in Bacillus sp. ZZV12-4809, v katerih smo našli številne potencialne dejavnike virulence. V lončnih poskusih in na mikroparcelah je sev I-1582 zmanjšal število ogorčic M. luci za 51-53 % v primerjavi s kontrolo. Bakterije I-1582 so delovale nematicidno ter spodbudile rast rastlin, kar smo pokazali z meritvami morfologije rastlin, relativne vsebnosti klorofila, vsebnostjo elementov in analizo hiperspektralnih posnetkov. Z analizo hiperspektralnih posnetkov z nadzorovano klasifikacijo smo uspešno razlikovali med rastlinami tretiranimi z B. firmus in rastlinami brez bakterij – v lončnem poskusu smo dosegli 97,4 % uspešnost, na mikroparcelah pa 96,3 %.

Keywords

ogorčice koreninskih šišk;filogenomika;hiperspektralno slikanje;biotično varstvo rastlin;Meloidogyne spp.;Bacillus firmus;doktorske disertacije;

Data

Language: Slovenian
Year of publishing:
Typology: 2.08 - Doctoral Dissertation
Organization: KIS - Agricultural Institute of Slovenia
Publisher: [N. Susič]
UDC: 632.937:595.161:528.8.041.5(043.3)
COBISS: 35594755 Link will open in a new window
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Downloads: 133
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Other data

Secondary language: English
Secondary title: The use of advanced technologies for integrated management of root-knot nematodes (Meloidogyne spp., Nematoda: Meloidogynidae)
Secondary abstract: Tropical root-knot nematodes (RKN) are extremely polyphagous pests causing large yield losses in agriculture. Some species, such as Meloidogyne ethiopica, M. inornata and M. luci (MEG) are highly related and difficult to distinguish. We sequenced 7 RKN isolates from the MEG group and following the genome assembly, determined their phylogenetic position within the genus. The genome assembly of M. luci SI-Smartno V13 is currently the most complete publicly available RKN genome, having 327 contigs, N50 contig size of 1.7 Mb, and final assembly size of 209.2 Mb. Phylogenetic analysis showed the positioning of all MEG-group isolates within a single monophyletic clade, and the species M. luci differed significantly from the species M. ethiopica and M. inornata. We tested the applicability of hyperspectral imaging for the early differentiation of biotic stress (RKN infestation) from abiotic stress (drought) in tomato plants. Using hyperspectral image analysis in the 400-2500 nm spectral range, it was possible to distinguish well-watered from water deficient plants with 100 % accuracy; and nematode-infested from healthy plants with 90-100 % accuracy. We also evaluated nematicidal activity and analysed the genomes of Bacillus firmus I-1582 and Bacillus sp. ZZV12-4809 and found multiple putative virulence factors. In the pot experiments as well as in the microplots, the strain I-1582 reduced M. luci infestation rates by 51-53 % compared to untreated control. I-1582 showed nematicidal and plant-growth promoting effects, as indicated by plant morphology measurements, relative chlorophyll content, leaf nutrient composition, and hyperspectral image analysis. Utilising supervised classification for hyperspectral image analysis, we successfully discriminated between B. firmus-treated and untreated plants – in the pot experiment we achieved 97.4 % and in the microplot experiment 96.3 % classification success.
Secondary keywords: root-knot nematodes;phylogenomics;hyperspectral imaging;biological pest control;Meloidogyne spp.;Bacillus firmus;
Type (COBISS): Doctoral dissertation
Study programme: 0
Embargo end date (OpenAIRE): 1970-01-01
Thesis comment: Univ. v Ljubljani, Biotehniška fak.
Pages: XIII, 174, [13] str.
ID: 12111847