Project description:To investigate the impact of a plant´s response to abiotic stress on plant defense against subsequent biotic stress, we determined the transcriptional response of Arabidopsis thaliana to low temperature stress (4°C) and subsequent mechanical wounding or larval feeding damage by the herbivores Mamestra brassicae (generalist) and Pieris brassicae (specialist). In total, 21%, 4% and 14% of all genes responsive to M. brassicae, P. brassicae or mechanical wounding were differentially regulated in previously cold-treated compared to untreated plants.
Project description:Activation of plant defence in Brassica napus L. cv. Westar and transgenic MINELESS plants after attack by Mamestra brassicae (cabbage moth)
Project description:Plants within the Brassicaceae family have a unique defence mechanism known as the “glucosinolate-myrosinase” system. Upon tissue disruption by insect herbivores, glucosinolates are hydrolysed by the enzyme myrosinase (EC 3.2.1.147) into a variety of degradation products, which can deter insect herbivory. This process has been termed as “The Mustard Oil Bomb”. Seeds of Brassica napus have been genetically modified to remove myrosinase containing myrosin cells. The modified plants have been named MINELESS due to a lack of toxic mines in seeds. This study aimed to get insights into defence responses of B. napus wild-type and MINELESS seedlings, after being challenged by larvae of the generalist herbivore Mamestra brassicae. The microarray analysis showed 494 and 159 genes to be differentially regulated after M. brassicae feeding on wild-type and MINELESS seedlings, respectively. Many of the observed transcriptional responses i B. napus and the MINELESS mutant are related to those found in Arabidopsis thaliana plants when they are exposed to insects.
Project description:We used our newly ultra deep sequence data and bioinformatics to re-annotate P. xylostella genome for high confidence miRNAs with the correct 5p and 3p arm features. Furthermore, the whole genome was screened to identify potential miRNA binding sites using three target-predicting algorithms. Totally, 203 mature miRNAs were annotated, including 33 novel miRNAs. Two geographical populations of Diamondback moth larvae from Queensland (Gatton) and South Australia (Waite) were collected and reared on the cabbage plant at the University of Queensland in Australia. Total RNA was extracted from fifteen 3rd instar larval samples using Triazol® following the manufacturerâs protocol (Life Technologies). The small RNA libraries were generated from both populations with three biological replicates using the Illumina Truseq small RNA preparation kit at the Australian Genome Research Facility (AGRF-Melbourne, Australia). The purified cDNA libraries were sequenced on Illumina HiSeq and raw sequencing reads (50 nt) were obtained using Illuminaâs Sequencing Control Studio software.
Project description:Brassica nigra plants, a Brassicaceae close to Arabidopsis thaliana, was used for combined stresses experiments. In this study, we performed a whole-genome microarray analysis on five-week-old plants and compared untreated plants and plants treated different single or dual stresses: the larvae Pieris brassicae, egg extract of Pieris brassicae, the bacterial Xanthomonas campestris pv. raphani, the aphid Brevicoryne brassicae or by combined stresses eggs of P. brassicae / P. brassicae, X. campestris / P. brassicae, B. brassicae / P. brassicae.
Project description:Although Plasmodiophora brassicae is one of the most common pathogens worldwide, the causal agent of clubroot disease in Brassica crops, resistance mechanisms to it are still only poorly understood. To study the early defense response induced by P. brassicae infection, a global transcriptome profiling of the roots of two near-isogenic lines (NILs) of clubroot-resistant (CR BJN3-2) and clubroot-susceptible (BJN3-2) Chinese cabbage (Brassica rapa) was performed by RNA-seq. Among the 42,730 unique genes mapped to the reference genome of B. rapa, 1,875 and 2,103 genes were found to be up- and down-regulated between CR BJN3-2 and BJN3-2, respectively, at 0, 12, 72, and 96 hours after inoculation (hai). Functional annotation showed that most of the differently expressed genes are involved in metabolism, transport, signal transduction, and defense. Of the genes assigned to plant-pathogen interactions, 151 showed different expression patterns between two NILs, including genes associated with pathogen-associated molecular patterns (PAMPs) and effectors recognition, calcium ion influx, hormone signaling, pathogenesis-related (PR) genes, transcription factors, and cell wall modification. In particular, the expression level of effector receptors (resistance proteins), PR genes involved in salicylic acid (SA) signaling pathway, were higher in clubroot-resistant NIL, while half of the PAMP receptors were suppressed in CR BJN3-2. This suggests that there was a more robust effector-triggered immunity (ETI) response in CR BJN3-2 and that SA signaling was important to clubroot resistance. The dataset generated by our transcriptome profiling may prove invaluable for further exploration of the different responses to P. brassicae between clubroot-resistant and clubroot-susceptible genotypes, and it will strongly contribute to a better understanding of the molecular mechanisms of resistance genes of B. rapa against P. brassicae infection.
