Tenuta, A. | bioRxiv Science

bioRxiv2023

Soybean-SCN duel: Novel insight into Soybean's Resistant Responses to Heterodera glycines

Soybean cyst nematodes (SCN, Heterodera glycines Ichinohe) are a significant threat to soybean production globally, causing severe yield losses and necessitating the development of effective strategies to combat this devastating nematode disease. This study presents dual RNA-seq analyses of the three most common SCN-resistant lines (Plant Introduction (PI) 437654, 548402, and 88788) and the susceptible line Lee74 against the SCN HG type 1.2.5.7 to identify the mechanisms of resistance and virulence genes involved in resistance breakdown. Transcriptomic and pathway analyses reveal the activation of the phenylpropanoid pathway, MAPK signaling pathway, plant hormone signal transduction, and secondary metabolite pathways in the resistance mechanisms. PI 437654, which exhibited robust resistance (female index, FI=0%), demonstrated unique gene expression associated with cell wall reinforcement, oxidative enzymes, ROS scavengers, and Ca+2 sensors governing the salicylic acid (SA) biosynthesis process, indicating its key defense mechanism. Moreover, using different hosts with varying levels of immunity and a susceptible line provided insights into SCN pathogenesis and how H. glycine overcomes different layers of host immunity by modulating its virulence genes. This research provides novel insights into the molecular mechanisms underlying soybean-SCN interactions and identifies potential targets for developing strategies to manage this devastating nematode disease.

plant biology↗

bioRxiv2022

Population genomics provide insights into the global genetic structure of Colletotrichum graminicola, the causal agent of maize anthracnose

BackgroundColletotrichum graminicola, the causal agent of maize anthracnose, is an important crop disease worldwide. Understanding the genetic diversity and mechanisms underlying genetic variation in pathogen populations is crucial to the development of effective control strategies. The genus Colletotrichum is largely recognized as asexual, but several species have been reported to have a sexual cycle. Here, we employed a population genomics approach to investigate the genetic diversity and reproductive biology of C. graminicola isolates infecting maize. We sequenced 108 isolates of C. graminicola collected in 14 countries using restriction site-associated DNA sequencing (RAD-Seq) and whole-genome sequencing (WGS). ResultsClustering analyses based on single-nucleotide polymorphisms showed populational differentiation at a global scale, with three genetic groups delimited by continental origin, compatible with short-dispersal of the pathogen, and geographic subdivision. Distinct levels of genetic diversity were observed between these clades, suggesting different evolutionary histories. Intra and inter-continental migration was predicted between Europe and South America, likely associated with the movement of contaminated germplasm. Low clonality and evidence of genetic recombination were detected from the analysis of linkage disequilibrium and the pairwise homoplasy index (PHI) test for clonality. We show evidence that even if rare (possibly due to losses of sex and meiosis-associated genes) C. graminicola can undergo sexual recombination based on lab assays and genomic analyses. ConclusionsOur results support hypotheses of intra and intercontinental pathogen migration and genetic recombination with great impact on C. graminicola population structure.

genomics↗