Biology subjects

Dixelius, C.

Publications and source records attributed to Dixelius, C..

4 recordsLinked to original sources

bioRxiv2026

Argonaute 15 regulates immunity of potato to filamentous pathogens through transposon-derived small RNAs

Canonical ribonucleases such as Argonaute (AGO) participate in RNA-based gene regulatory processes. They are important for small RNA (sRNA) association and the formation of RNA-induced RNA silencing complexes. Potato (Solanum tuberosum) has 14 AGO-encoding genes, including the Solanum-specific StAGO15, which is activated upon infection by filamentous pathogens. The resistant phenotype conferred by ectopic expression of StAGO15 was abolished in plants in which a 21-nt sequence in the PAZ-encoding region of StAGO15 was targeted using an artificial miRNA. We then analyzed the sRNAs associated with StAGO15 in Phytophthora infestans leaf infection. Small RNAs were coimmunoprecipitated, subjected to deep sequencing, and analyzed against the P. infestans and potato genomes, in which cleavage sites were predicted by applying the R package, smartPARE. The most notable difference between pathogen- and water-inoculated StAGO15 samples was observed in the transposon (TE) category. Here, two categories of nonautonomous TE dominated: the miniature inverted-repeat transposable elements (MITEs) and short interspersed nuclear elements. The StAGO15-associated sRNAs bind and target complementary endogenous potato RNAs. One example is siRNA122, which acts on a cleavage site in the resistance gene PGSC0003DMG400015681 (StRES1). siRNA122 is derived from a MITE; upon deletion of this source sequence, resistance is restored. Our findings provide new insights into the plant immune surveillance network and demonstrate that deleting a 21 nt RNA sequence from a MITE transposon released a defense response, against two important filamentous pathogens.

plant biology↗

bioRxiv2020

Phytophthora infestans Ago1-bound miRNA promotes potato late blight disease

O_LIPhytophthora spp. incite serious plant damages by exploiting a large number of effector proteins and small RNAs (sRNAs). Several reports are describing modulation of host RNA biogenesis and defence gene expression. Here, we analysed P. infestans Argonaute (Ago) 1 associated small RNAs during potato leaf infection. C_LIO_LIsRNAs were co-immunoprecipitated, deep sequenced and analysed against the P. infestans and potato genomes, followed by transgenic and biochemical analyses on a predicted host target. C_LIO_LIExtensive targeting of potato and pathogen-derived sRNAs to a large number of mRNAs was observed, including 206 sequences coding for resistance (R) proteins in the host genome. The single miRNA encoded by P. infestans (miR8788) was found to target a potato lipase-like membrane protein-encoding gene (StLL1) localized to the tonoplast. Analyses of stable transgenic potato lines harbouring overexpressed StLL1 or artificial miRNA gene constructs demonstrated the importance of StLL1 during infection by P. infestans. Similarly, a miR8788 knock-down strain showed reduced growth on potato compared to the wild-type strain 88069. C_LIO_LIThe data suggest that sRNA encoded by P. infestans can affect potato mRNA and thereby promote disease. Knowledge of the impact of pathogen small RNAs in plant defence mechanisms is of major significance to succeed in improved disease control management. C_LI

plant biology↗

bioRxiv2019

Induced expression of Xerophyta viscosa XvSap1 gene greatly impacts tolerance to drought stress in transgenic sweetpotato

Key message Drought stress in sweetpotato could be overcome by introducing XvSap1 gene from Xerophyta viscosa.\n\nDrought stress often leads to reduced yields and is perilous delimiter for expanded cultivation and increased productivity of sweetpotato. Cell wall stabilization proteins have been identified to play a pivotal role in mechanical stabilization during desiccation stress mitigation. They are involved in myriad cellular processes that modify the cell wall properties to tolerate the mechanical stress during dehydration in plants. This provides a possible approach to engineer crops for enhanced stable yields under adverse climatic conditions. In this study, we introduced the XvSap1 gene isolated from Xerophyta viscosa, a resurrection plant into sweetpotato by Agrobacterium-mediated transformation. Detection of the transgene by PCR coupled with Southern blot revealed the integration of XvSap1 in the three independent events. Sweetpotato plants expressing the XvSap1 gene exhibited superior growth performance such as shoot length, number of leaves and yield than the wild type plants under drought stress. Quantitative real time-PCR results confirmed higher expression of the XvSap1 gene in XSP1 transgenic plants imposed with drought stress. In addition, the transgenic plants had increased levels of chlorophyll, free proline and relative water content but malonaldehyde content was decreased under drought stress compared to wild type plants. Conjointly, our findings show that XvSap1 can enhance drought resilience without causing deleterious phenotypic and yield changes, thus providing a promising candidate target for improving the drought tolerance of sweetpotato cultivars through genetic engineering. The transgenic drought tolerant sweetpotato line provides a valuable resource as drought tolerant crop on arid lands of the world.

molecular biology↗

bioRxiv2018

The Rhizoctonia solani LysM and RlpA-like effector proteins contribute to virulence suppressing chitin-triggered immunity and hypersensitive response

Rhizoctonia (in Greek \"root-killer\") species and particularly R. solani attacks a broad range of plant species and crops. It belongs to Basidiomycota and is a soil-borne pathogen causing mainly damping-off diseases of seedlings and root rot, although it can infect plants in any stage. Despite the severity of this disease, many aspects in R. solani infection biology still remain to be elucidated. Here we investigated the role of two effector candidates, predicted from the genome of a R. solani AG2-2IIIB strain that uses sugar beet as a host. Gene expression analysis showed that genes encoding for a LysM effector and a rare lipoprotein-A-like protein (RsRlpA) were induced upon early infection stages. When heterologous expressed in Cercospora beticola the two genes contributed to virulence. The RsLysM effector showed chitin- binding affinity and suppression of chitin-triggered immunity but could not protect hyphae from hydrolysis. The RsRlpA effector suppressed hypersensitive response in Nicotiana benthamiana leaves. Overall, this study provides us with valuable information on R. solani infection biology, implying that this organism relies on mechanisms similar to hemibiotrophic pathogens in order to establish a successful infection.

plant biology↗