Heiden, N. | Search bioRxiv

bioRxiv2022

Comparative genomics of Minnesotan barley-infecting Xanthomonas translucens shows overall genomic similarity but virulence factor diversity

Xanthomonas translucens pv. translucens (Xtt) is a global barley pathogen and a concern for resistance breeding and regulation. Long-read whole genome sequences allow in-depth understanding of pathogen diversity. We have completed long-read PacBio sequencing of two Minnesotan Xtt strains and an in-depth analysis of available Xtt genomes. We found that average nucleotide identity(ANI)-based approaches organize Xtt strains differently than the previously standard MLSA approach. According to ANI, Xtt forms a separate clade from Xanthomonas translucens pv. undulosa and consists of three main groups which are represented on multiple continents. The global distribution of Xtt groups suggests that regulation of seed is not important for prevention of Xtt spread. Some virulence factors, such as 17 Type III-secreted effectors, are highly conserved and offer potential targets for the elicitation of broad resistance. However, there is a high degree of variation in virulence factors meaning that germplasm should be screened for resistance with a diverse panel of Xtt.

genomics↗

bioRxiv2021

Do soil features condition seed germination of gypsum plants? An analysis of the effect of different natural soils

Gypseous soils are widespread across arid and semiarid environments worldwide. They present remarkable challenges to plants and host a unique flora. We aimed to assess up to what point the specificity and distribution of species on gypsum might be driven by species-specific germination responses to soil gypsum availability. We analyzed the germination of six gypsum specialists and four closely related generalist plant species from the Iberian Peninsula and the Chihuahuan Desert in four different field soils with contrasting concentrations of gypsum, pH and soil texture. Plant restriction to gypsum was unrelated to the germinating ability of seeds on different substrates. Irrespective of their affinity for gypsum, most species germinated better on mixed gypsum-calcareous soil and worse in the acidic soil treatment. Our data suggest soil pH was the main soil feature driving seed germination, while the effect of gypsum content was generally not significant. The main exception was the Iberian gypsum specialist Helianthemum squamatum (L.) Dum. Cours., which showed increased germination on gypseous soils and higher germination in response to increased soil gypsum content. Except for this species, our findings indicate alkaline soils favor the germination of most of the species analyzed, irrespectively of their gypsum content. HighlightsO_LIGypsum soils are one of the most widespread special substrates of the world C_LIO_LIWe evaluated the effects of natural soils on the germination of gypsum plants C_LIO_LISoil pH was the main soil feature driving seed germination C_LIO_LIThe effect of gypsum content was not significant C_LIO_LIWe suggest a potential origin of gypsophiles from plants adapted to alkaline soils C_LI

ecology↗