Project description:The effect of site, cold storage, and scion genotype on the apple root microbiome and its effect on apple canker (Neonectria ditissima) severity
Project description:Comparative analyze at the transcriptomic level 1) of Venturia inaequalis apple host resistance via the major resistance gene Rvi6, in Rvi6 overexpressing transgenic apple versus ‘Gala’ susceptible variety; 2) of Venturia pyrina apple nonhost resistance, in ‘Gala’ variety, 24 and 72 hours post inoculation.
Project description:Ontogenic scab resistance in apple leaves and fruits is a horizontal resistance against the plant pathogen VenturiaM- inaequalis and is expressed as decrease of disease symptoms and incidence with the ageing of the leaves. Several studies at biochemical level tried to unveil the nature of this resistance, however without any conclusive results. We decided therefore to investigate the genetic origin of this phenomenon by performing a full quantitative trascriptome sequencing and comparison of young (susceptible) and old (ontogenic resistant) leaves, infected or not with the pathogen. Two time points at 72 and 96 hours post inoculation were chosen for RNA sampling and sequencing. Comparison between the different conditions (young and old leaves, inoculated or not) should allow finding genes differentially expressed which may represent different induced plant defense reaction leading to ontogenic resistance or be the cause for a constitutive (not inoculated with the pathogen) shift toward resistance in old leaves. Differentially expressed genes were then characterized for their function by homology to A.M- thaliana and other plantsM-^R genes, particularly looking for genes involved in pathways already suspected of appertaining to ontogenic resistance in apple or other hosts, or to plant defense mechanisms in general.
Project description:Fire blight (FB) is a bacterial disease affecting plants from Rosaceae family, including apple and pear. FB develops after the infection of Erwinia amylovora, gram-negative enterobacterium, and results in burnt-like damages and wilting, which can affect all organs of the plant. Although the mechanisms underlying disease response in apples are not elucidated yet, it has been well described that FB resistance depends on the rootstock type. The main objective of this work was to identify miRNAs involved in response to bacterial infection in order to better explain apple defense mechanisms against fire blight disease. We performed deep sequencing of eighteen small RNA libraries obtained from inoculated and non-inoculated Gala apple leaves. 233 novel plant mature miRNAs were identified together with their targets and potential role in response to bacterial infection. We identify three apple miRNAs responding to inoculation (mdm-miR168a,b, mdm-miR194C and mdm-miR1392C) as well as miRNAs reacting to bacterial infection in a rootstock-specific manner (miR395 family). Our results provide insights into the mechanisms of fire blight resistance in apple.