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Evaluation of different antimicrobial agents for laboratory and field against Pantoea agglomerans, the causative agent of bacterial leaf blight disease on oat (Avena sativa)

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Evaluation of different antimicrobial agents for laboratory and field against Pantoea agglomerans, the causative agent of bacterial leaf blight disease on oat (Avena sativa)

Laboratory and field experiments on the efficacy of 13 antimicrobial agents against oat leaf blight disease (Pantoea agglomerans) found that zhongshengmycin and ethylicin have excellent control efficacy.


Abstract

Leaf blight disease (LBD) caused by Pantoea agglomerans is a newly emerged oat disease in China that causes great economic and yield losses of oat production. Laboratory and field experiments were conducted to evaluate the efficacy of 13 antimicrobial agents against P. agglomerans and recommend agents with better control efficacy for use. The antibacterial potential of four concentrations of each agent was evaluated under in vitro conditions. Zhongshengmycin and ethylicin were the most effective in inhibiting the growth of P. agglomerans; their bacteriostatic rates (85.0% and 84.8%, respectively) were higher while EC50 lower (0.31 and 0.90, respectively) than other agents. The greenhouse and field experiment suggested that the greatest fresh weight per plant (57.26 g and 57.93 g), forage yield (22.53 t/ha and 22.21 t/ha) and control efficacy (>75%) were obtained after spraying twice with zhongshengmycin or ethylicin in the LBD occurrence phase, with lower yields and control by kasugamycin + dicopper chloride trihydroxide, kasugamycin + oxine copper, benziothiazolinone, copper hydroxide, phenanthrenecarboxylicacid, copper, picoxystrobin, chloroisobromine cyanuric acid, oxathiapiprolin or azoxystrobin. Foliar application of zhongshengmycin or ethylicin can therefore be used for the effective management of LBD of oat.

Genomic prediction of seed nutritional traits in biparental families of oat (Avena sativa)

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Abstract

Selection for more nutritious crop plants is an important goal of plant breeding to improve food quality and contribute to human health outcomes. While there are efforts to integrate genomic prediction to accelerate breeding progress, an ongoing challenge is identifying strategies to improve accuracy when predicting within biparental populations in breeding programs. We tested multiple genomic prediction methods for 12 seed fatty acid content traits in oat (Avena sativa L.), as unsaturated fatty acids are a key nutritional trait in oat. Using two well-characterized oat germplasm panels and other biparental families as training populations, we predicted family mean and individual values within families. Genomic prediction of family mean exceeded a mean accuracy of 0.40 and 0.80 using an unrelated and related germplasm panel, respectively, where the related germplasm panel outperformed prediction based on phenotypic means (0.54). Within family prediction accuracy was more variable: training on the related germplasm had higher accuracy than the unrelated panel (0.14–0.16 and 0.05–0.07, respectively), but variability between families was not easily predicted by parent relatedness, segregation of a locus detected by a genome-wide association study in the panel, or other characteristics. When using other families as training populations, prediction accuracies were comparable to the related germplasm panel (0.11–0.23), and families that had half-sib families in the training set had higher prediction accuracy than those that did not. Overall, this work provides an example of genomic prediction of family means and within biparental families for an important nutritional trait and suggests that using related germplasm panels as training populations can be effective.

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

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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.

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

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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

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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.

Understanding the salt overly sensitive pathway in Prunus: Identification and characterization of NHX, CIPK, and CBL genes

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Abstract

Salinity is a major abiotic stress factor that can significantly impact crop growth, and productivity. In response to salt stress, the plant Salt Overly Sensitive (SOS) signaling pathway regulates the homeostasis of intracellular sodium ion concentration. The SOS1, SOS2, and SOS3 genes play critical roles in the SOS pathway, which belongs to the members of Na+/H+ exchanger (NHX), CBL-interacting protein kinase (CIPK), and calcineurin B-like (CBL) gene families, respectively. In this study, we performed genome-wide identifications and phylogenetic analyses of NHX, CIPK, and CBL genes in six Rosaceae species: Prunus persica, Prunus dulcis, Prunus mume, Prunus armeniaca, Pyrus ussuriensis × Pyrus communis, and Rosa chinensis. NHX, CIPK, and CBL genes of Arabidopsis thaliana were used as controls for phylogenetic analyses. Our analysis revealed the lineage-specific and adaptive evolutions of Rosaceae genes. Our observations indicated the existence of two primary classes of CIPK genes: those that are intron-rich and those that are intron-less. Intron-rich CIPKs in Rosaceae and Arabidopsis can be traced back to algae CIPKs and CIPKs found in early plants, suggesting that intron-less CIPKs evolved from their intron-rich counterparts. This study identified one gene for each member of the SOS signaling pathway in P. persica: PpSOS1, PpSOS2, and PpSOS3. Gene expression analyses indicated that all three genes of P. persica were expressed in roots and leaves. Yeast two-hybrid-based protein–protein interaction analyses revealed a direct interaction between PpSOS3 and PpSOS2; and between PpSOS2 and PpSOS1C-terminus region. Our findings indicate that the SOS signaling pathway is highly conserved in P. persica.

Identification of Piper species that are resistant to Phytophthora capsici, Meloidogyne incognita, and waterlogging in Vietnam

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Identification of Piper species that are resistant to Phytophthora capsici, Meloidogyne incognita, and waterlogging in Vietnam

Two Piper accessions P. divaricatum and P. hancei in Vietnam demonstrated high levels of resistance to pathogenic Phytophthora capsici, the root-knot nematode Meloidogyne incognita and tolerance towards waterlogged conditions.


Abstract

Black pepper (Piper nigrum) is a spice commonly used in kitchens throughout the world. Black pepper production is devastated by a range of pathogenic agents, including Phytophthora capsici and Meloidogyne incognita. Many efforts have been directed towards finding black pepper cultivars that are resistant to these pathogens. In this work, a 39-accession germplasm panel of species in the Piper family collected throughout Vietnam was described. Preliminary tests using P. capsici inoculation onto leaves were carried out to identify potentially resistant accessions. Next, candidate plants were inoculated with P. capsici mycelial suspension and survival rates were assessed 15, 30 and 45 days postinoculation. In addition, Piper plants were challenged with M. incognita by adding larvae/juveniles to growing pots. Resistance to M. incognita was determined by the number of root galls and the percentage of plants with yellow leaves 1, 2 and 4 months after treatment. Piper accessions were also subjected to a 4-day waterlogged treatment. Two accessions (HUIB_PH30 and HUIB_PD36) demonstrated high levels of resistance to all biological and water stresses. Micromorphological characterizations revealed that the amount of intercellular spaces in the root cortex correlated with the resistance to P. capsici and waterlogging tolerance. Hence, the abundance of intercellular spaces can serve as a guide for further selection of black pepper accessions that are resistant to common diseases and tolerant to waterlogged conditions.

Evaluation of soybean genotypes for cowpea mild mottle virus resistance through phenotypic reaction and genotypic analysis

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Evaluation of soybean genotypes for cowpea mild mottle virus resistance through phenotypic reaction and genotypic analysis

Soybean genotypes were screened under field and controlled conditions to identify and characterize, through gene-specific and SSR molecular markers, genotypes resistant against CPMMV infection.


Abstract

Cowpea mild mottle virus (CPMMV), a carlavirus nonpersistently transmitted by whiteflies, is an emerging and economically important virus of soybean. The present study aimed to identify soybean genotypes resistant to CPMMV through mechanical inoculation-based phenotyping and marker trait association using gene-specific and simple-sequence repeat (SSR) markers. A set of 500 soybean genotypes was initially screened in the field for CPMMV infection, of which 288 genotypes showing resistance were evaluated further under controlled glasshouse conditions. Among these 288 genotypes, 43 (14.9%) were resistant, 59 (20.5%) were moderately resistant while the remaining 186 (64.6%) were susceptible. A set of five gene-specific primer pairs, three of which targeted CPMMV R genes, was used for screening the 288 soybean genotypes; 96 genotypes from the 288 (based on disease score) were also genotyped with 24 SSR polymorphic markers for an association study. The mean values of major allele frequency and gene diversity were found to be 0.70 and 0.39, respectively. The polymorphism information content varied from 0.14 to 0.37. Population structure and cluster analysis revealed three subpopulations for the five gene-specific markers and two distinct subpopulations for the 24 SSR markers, respectively. Neighbour joining-based clustering analysis categorized the 288 genotypes into two major clusters. Three markers were found to be significantly associated with CPMMV resistance. The BARCSOYSSR0558 marker showed the highest phenotypic variance of 9.6%. The present study will help in identification of CPMMV R genes and breeding new resistant varieties through marker-assisted selection.

Diversity of Colletotrichum species causing anthracnose on three oak species (Quercus acutissima, Q. mongolica and Q. variabilis) in China

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Diversity of Colletotrichum species causing anthracnose on three oak species (Quercus acutissima, Q. mongolica and Q. variabilis) in China

The pathogenic species diversity of Colletotrichum on Quercus species from seven locations was assessed by morphological and phylogenetic analyses of ITS, gapdh, chs-1, act and tub2 sequences; nine species were identified.


Abstract

Anthracnose of oak (Quercus) caused by Colletotrichum spp. is one of the most common diseases in oak forests. To investigate the species diversity of Colletotrichum associated with oak anthracnose, symptomatic leaf samples of three oak species (Q. acutissima, Q. mongolica and Q. variabilis) were collected from Anhui, Hainan, Henan, Shaanxi and Shandong Provinces, Inner Mongolia Autonomous Region, and Beijing City in China from 2019 to 2022. A total of 219 Colletotrichum isolates were obtained and identified by morphological and phylogenetic analyses of the rDNA internal transcribed spacer (ITS), glyceraldehyde-3-phosphate dehydrogenase (gapdh), chitin synthase 1 (chs-1), actin (act) and β-tubulin (tub2) sequences. Nine species were identified: C. fioriniae (two isolates, 0.9%), C. camellia-japonicae (two isolates, 0.9%), C. karstii (three isolates, 1.4%), C. quercicola (two isolates, 0.9%), C. aenigma (three isolates, 1.4%), C. endophyticum (two isolates, 0.9%), C. fructicola (68 isolates, 31.1%), C. gloeosporioides sensu stricto (74 isolates, 33.8%) and C. siamense (63 isolates, 28.8%). Pathogenicity was confirmed using Koch's postulates, which showed that five species (C. camellia-japonicae, C. endophyticum, C. fructicola, C. gloeosporioides s. s. and C. siamense) caused Q. acutissima anthracnose, four species (C. karstii, C. fructicola, C. gloeosporioides s. s. and C. siamense) caused Q. mongolica anthracnose and six species (C. fioriniae, C. quercicola, C. aenigma, C. fructicola, C. gloeosporioides s. s. and C. siamense) caused Q. variabilis anthracnose. This study demonstrates the pathogenic species diversity of Colletotrichum on Q. acutissima, Q. mongolica and Q. variabilis.