Efficiency of indirect selection for fusarium head blight resistance and mycotoxin accumulation in winter wheat (Triticum aestivum L.)

Posted on by

Abstract

Fusarium head blight (FHB) is one of the most devastating diseases of wheat and can lead to significant yield losses as well as a contamination of the crop with mycotoxins that are a major concern in cereal-based food and feed products. The aims of this study were thus to investigate the relationship between resistance against multiple Fusarium species and to assess the potential of an indirect phenotypic and genomic selection for the resistance against the accumulation of several mycotoxins in wheat. Strong phenotypic and genetic correlations between the mycotoxin contents, FHB severity and FHB-associated traits were observed, irrespective of if traits were assessed in trials inoculated with a DON or HT-2/T-2 producing Fusarium species. A multi-stage phenotypic or genomic selection with low anther retention being used for an indirect selection among early generation selection candidates, followed by an evaluation of the pre-selected set in disease nurseries, and lastly by assessing the mycotoxin content of the most promising genotypes is suggested as a suitable strategy to breed for wheat cultivars with reduced risk of mycotoxin accumulation.

Potato cyst nematodes: A persistent and fearsome foe

Posted on by
Potato cyst nematodes: A persistent and fearsome foe

This review provides case studies on Globodera pallida, Globodera rostochiensis and Globodera ellingtonae, for a historical view of how scientists and potato experts have responded to PCN pandemics and the effectiveness of management strategies.


Abstract

Nematodes, commonly called roundworms, represent one of the largest phyla of animals. Plant-parasitic nematodes cause significant economic losses in major crops worldwide, and cyst nematodes (Heterodera spp. and Globodera spp.) are among the most damaging species. This review focuses on three main species, Globodera pallida, Globodera rostochiensis and Globodera ellingtonae, collectively known as potato cyst nematodes (PCNs). G. rostochiensis and G. pallida are the most commonly occurring species in potato-growing areas and are considered to have originated from the Andes region in South America and introduced then to Europe in the 1850s and now occur globally in more than 75 countries. PCNs feed entirely inside the root and produce distinctive cysts containing eggs. PCNs reduce root development, stunt the growth of potato plants and ultimately lead to the production of fewer and smaller tubers. PCNs are feared because of their ability to survive for up to 40 years in the soil in the absence of potatoes, and once established they are incredibly difficult to eradicate. Five case studies in this review provide an historical overview of how scientists and potato experts have responded to PCN pandemics and the effectiveness of management strategies.

Integrative multi‐omics analyses of date palm (Phoenix dactylifera) roots and leaves reveal how the halophyte land plant copes with sea water

Posted on by

Abstract

Date palm (Phoenix dactylifera L.) is able to grow and complete its life cycle while being rooted in highly saline soils. Which of the many well-known salt-tolerance strategies are combined to fine-tune this remarkable resilience is unknown. The precise location, whether in the shoot or the root, where these strategies are employed remains uncertain, leaving us unaware of how the various known salt-tolerance mechanisms are integrated to fine-tune this remarkable resilience. To address this shortcoming, we exposed date palm to a salt stress dose equivalent to seawater for up to 4 weeks and applied integrative multi-omics analyses followed by targeted metabolomics, hormone, and ion analyses. Integration of proteomic into transcriptomic data allowed a view beyond simple correlation, revealing a remarkably high degree of convergence between gene expression and protein abundance. This sheds a clear light on the acclimatization mechanisms employed, which depend on reprogramming of protein biosynthesis. For growth in highly saline habitats, date palm effectively combines various salt-tolerance mechanisms found in both halophytes and glycophytes: “avoidance” by efficient sodium and chloride exclusion at the roots, and “acclimation” by osmotic adjustment, reactive oxygen species scavenging in leaves, and remodeling of the ribosome-associated proteome in salt-exposed root cells. Combined efficiently as in P. dactylifera L., these sets of mechanisms seem to explain the palm's excellent salt stress tolerance.

Contrasting interactions of the aggressive Verticillium longisporum lineage A1/D1 and the non‐aggressive A1/D2 lineage with roots of oilseed rape

Posted on by
Contrasting interactions of the aggressive Verticillium longisporum lineage A1/D1 and the non-aggressive A1/D2 lineage with roots of oilseed rape

The non-aggressive lineage A1/D2 of Verticillium longisporum penetrates roots of oilseed rape, however, without inducing typical disease symptoms, indicating tolerance in oilseed rape to A1/D2.


Abstract

Verticillium longisporum is a soilborne fungal vascular pathogen of Brassica crops. Three hybrid lineages originating from three independent hybridization events of four haploid Verticillium parents are known. V. longisporum lineage A1/D2 has only been found in horseradish and previous pathogenicity tests have shown that it is non-aggressive on oilseed rape (Brassica napus). The aim of this study was to investigate the interaction of the non-aggressive lineage A1/D2 with oilseed rape in comparison with the aggressive A1/D1 lineage. Although A1/D2 did not cause severe disease symptoms, the study revealed restricted root infection and systemic colonization by this lineage, as assessed by quantitative PCR of fungal DNA. Assessment of root surface colonization by confocal laser microscopy indicated early sporulation, disorganized loosely attached hyphal growth and hyphal coiling of A1/D2. By contrast, A1/D1 showed organized hyphal growth tight to the root surface, as well as hyphal swellings at points of penetration. Vascular colonization was studied with transmission electron microscopy, which revealed less vessel colonization, higher intensity of vascular responses and lower plant cell wall degradation in A1/D2-treated plants in comparison with A1/D1. Vascular responses consisted of strong coating of vessel walls and fungal hyphae with an electron-dense material, indicating higher intensity of plant defence in comparison with A1/D1. The results, for the first time, demonstrate stem colonization and thus a basic level of pathogenic interaction of non-aggressive strains of A1/D2 with oilseed rape associated with a lack of severe disease symptoms, which indicate tolerance in oilseed rape to lineage A1/D2.

Responses of rice cultivars with different cold tolerance to chilling in booting and flowering stages: An experiment in Northeast China

Posted on by

Abstract

Climate change has led to an increasing trend in the intensity of global extreme weather events, including chilling. Breeding cultivars with high cold tolerance could be an important pathway to mitigate the negative effects of climate change. For rice, few studies have been focusing on the responses of different cold-tolerance cultivars on chilling stress. In this study, we selected four japonica rice cultivars and conducted a chilling treatment experiment (with three chilling temperatures and three chilling durations) at the booting and flowering stages in 2020 and 2021 in Northeast China. The results showed that chilling treatment at the booting stage affected the biomass allocation and yield traits more than the chilling treatment at the flowering stage did. Overall, the chilling treatment affected the cold-sensitive cultivars more than the cold-tolerant cultivars. Among all the study yield traits, chilling treatment affected spikelet fertility the most, followed by the number of grains per panicle. For every 10°C day increase in CDD at the booting (flowering) stage, the grain yield per plant and spikelet fertility decreased by 4.8–12.8% and 3.6–10.8% (2.1–5.3% and 2.2–4.9%), respectively. Even with the intense chilling treatment, the cold-tolerant cultivars had relatively high number of effective spikes per plant, grain weight, and stable spikelet fertility, hence they maintained relatively high grain yield. Therefore, it is important to factor in the cold tolerance of the cultivars when assessing the chilling effects on biomass allocation and yield traits for rice. In order to combat the negative effects of extremely low temperature at the reproductive stage on rice grain yield, the future breeding technology could focus on improving the spikelet fertility, grain filling size, and number of spikes per plant.

Colletotrichum acericola sp. nov. from seeds of the invasive alien tree species Acer negundo in Poland

Posted on by
Colletotrichum acericola sp. nov. from seeds of the invasive alien tree species Acer negundo in Poland

Colletotrichum acericola sp. nov. was found in Wrocław, Poland on the seeds of an invasive alien boxelder. Based on comparisons with US prairie sequences, it is likely that it originated in North America and was introduced to Europe.


Abstract

The boxelder maple (Acer negundo, Sapindaceae) is one of the most common tree species of the genus Acer natively growing in North America. In the 17th century, A. negundo was introduced to Europe as an ornamental plant, and from this time, it started an uncontrolled expansion into new territories, threatening local ecosystems. Fungal development on invasive alien species' seeds and pedicels was observed in 2017 and 2021 in the municipality of Wrocław (Poland), outside of the native occurrence of the host. Morphological analyses combined with multilocus phylogenetic analyses (internal transcribed spacer [ITS], gapdh, act, tub2, chs-1 and his3 sequences) showed that isolates belonged to a new species of Colletotrichum, from the rare C. agaves species complex. The name Colletotrichum acericola is proposed for this fungus. Based on comparisons with sequences from NCBI GenBank originating from prairie plants in the United States, it is likely that C. acericola is native to North America.

Characterization of Xanthomonas hortorum isolates causing leaf spot on Primula vulgaris

Posted on by
Characterization of Xanthomonas hortorum isolates causing leaf spot on Primula vulgaris

A new pathovar, Xanthomonas hortorum pv. primulicola, was identified as the causative agent of leaf spot in Primula vulgaris based on taxonomic analysis, and distinct host ranges in comparison to other X. hortorum pathovars.


Abstract

The bacterial leaf spot of Primula vulgaris was reported from forest locations in Mazandaran province, Iran in 1995. The causative bacterium was initially identified as Xanthomonas campestris based on sequences of ITS and 16S rRNA regions. On the basis of sequences of gyrB and dnaK housekeeping genes, the isolates resembled strains of Xanthomonas hortorum. The present study was performed to clarify the taxonomic status of the incitant bacterium. Samples of P. vulgaris with leaf spot symptoms were collected from the Darabkola forest (Mazandaran province) and the bacterial strains were isolated on plates of glucose nutrient agar. Some isolates only induced hypersensitive reaction on geranium (Pelargonium × hortorum) leaves but a few isolates incited leaf spot symptoms when inoculated on P. vulgaris, P. heterochroma and P. × polyantha plants. The isolates were Gram stain, oxidase and urease negative but positive in tests for catalase and hydrolysis of gelatin, aesculin and Tween 80. Several unique nonpathogenic isolates were recovered with varying carbon source utilization profiles and different molecular features, including distinct ERIC-PCR profiles. Representative gyrB, rpoD, dnaK and fyuA housekeeping genes were amplified by PCR and sequenced for comparison with Xanthomonas species in the GenBank database using maximum-likelihood, maximum-parsimony and Bayesian algorithms to construct phylogenetic trees. The pathogenic and nonpathogenic strains were closely related to X. hortorum pathovars. Therefore, it is likely that these isolates belong to a new pathovar of X. hortorum. Based on previous studies and our findings, we propose naming the strain causing primrose leaf spot as X. hortorum pv. primulicola.