The fungal pathogen
causes the anthracnose of maize (
) and is responsible for significant yield losses worldwide. The genome of
was sequenced in 2012 using Sanger sequencing, 454 pyrosequencing, and ...an optical map to obtain an assembly of 13 pseudochromosomes. We re-sequenced the genome using a combination of short-read (Illumina) and long-read (PacBio) technologies to obtain a chromosome-level assembly. The new version of the genome sequence has 13 chromosomes with a total length of 57.43 Mb. We detected 66 (23.62 Mb) structural rearrangements in the new assembly with respect to the previous version, consisting of 61 (21.98 Mb) translocations, 1 (1.41 Mb) inversion, and 4 (221 Kb) duplications. We annotated the genome and obtained 15,118 predicted genes and 3,614 new gene models compared to the previous version of the assembly. We show that 25.88% of the new assembly is composed of repetitive DNA elements (13.68% more than the previous assembly version), which are mostly found in gene-sparse regions. We describe genomic compartmentalization consisting of repeat-rich and gene-poor regions vs. repeat-poor and gene-rich regions. A total of 1,140 secreted proteins were found mainly in repeat-rich regions. We also found that ~75% of the three smallest chromosomes (minichromosomes, between 730 and 551 Kb) are strongly affected by repeat-induced point mutation (RIP) compared with 28% of the larger chromosomes. The gene content of the minichromosomes (MCs) comprises 121 genes, of which 83.6% are hypothetical proteins with no predicted function, while the mean percentage of Chr1-Chr10 is 36.5%. No predicted secreted proteins are present in the MCs. Interestingly, only 2% of the genes in Chr11 have homologs in other strains of
, while Chr12 and 13 have 58 and 57%, respectively, raising the question as to whether Chrs12 and 13 are dispensable. The core chromosomes (Chr1-Chr10) are very different with respect to the MCs (Chr11-Chr13) in terms of the content and sequence features. We hypothesize that the higher density of repetitive elements and RIPs in the MCs may be linked to the adaptation and/or host co-evolution of this pathogenic fungus.
SORA: Stellar occultation reduction and analysis Gomes-Júnior, A R; Morgado, B E; Benedetti-Rossi, G ...
Monthly notices of the Royal Astronomical Society,
02/2022, Letnik:
511, Številka:
1
Journal Article
Recenzirano
Odprti dostop
ABSTRACT
The stellar occultation technique provides competitive accuracy in determining the sizes, shapes, astrometry, etc., of the occulting body, comparable to in-situ observations by spacecraft. ...With the increase in the number of known Solar system objects expected from the LSST, the highly precise astrometric catalogs, such as Gaia, and the improvement of ephemerides, occultations observations will become more common with a higher number of chords in each observation. In the context of the Big Data era, we developed sora, an open-source python library to reduce and analyse stellar occultation data efficiently. It includes routines from predicting such events up to the determination of Solar system bodies’ sizes, shapes, and positions.
is a large genus of plant pathogenic fungi comprising more than 200 species. In this work, we present the genome sequences of four
species pathogenic to soybean:
,
,
, and
While
is globally ...considered the most important pathogen, the other three species have been described and associated with soybean only recently. The genome sequences will provide insights into factors that contribute to pathogenicity toward soybean and will be useful for further research into the evolution of
Soybean (
) is among the most important crops in the world, and its production can be threatened by biotic diseases, such as anthracnose. Soybean anthracnose is a seed-borne disease mainly caused by ...the hemibiotrophic fungus
. Typical symptoms are pre- and post-emergence damping off and necrotic lesions on cotyledons, petioles, leaves, and pods. Anthracnose symptoms can appear early in the field, causing major losses to soybean production.
In preliminary experiments, we observed that the same soybean cultivar can have a range of susceptibility towards different strains of
, while the same
strain can cause varying levels of disease severity in different soybean cultivars. To gain a better understanding of the molecular mechanisms regulating the early response of different soybean cultivars to different
strains, we performed pathogenicity assays to select two soybean cultivars with significantly different susceptibility to two different
strains and analyzed their transcriptome profiles at different time points of interaction (0, 12, 48, and 120 h post-inoculation, hpi).
The pathogenicity assays showed that the soybean cultivar
1 is more resistant to
strain 1080, and it is highly susceptible to strain 1059, while cultivar
2 shows the opposite behavior. However, if only trivial anthracnose symptoms appeared in the more resistant phenotype (MRP;
1-1080;
2-1059) upon 120 hpi, in the more susceptible phenotype (MSP;
-1059;
2- 1080) plants show mild symptoms already at 72 hpi, after which the disease evolved rapidly to severe necrosis and plant death. Interestingly, several genes related to different cellular responses of the plant immune system (pathogen recognition, signaling events, transcriptional reprogramming, and defense-related genes) were commonly modulated at the same time points only in both MRP. The list of differentially expressed genes (DEGs) specific to the more resistant combinations and related to different cellular responses of the plant immune system may shed light on the important host defense pathways against soybean anthracnose.
Abstract Myrtle rust, caused by Austropuccinia psidii , has been associated with more than 480 plant species belonging to the family Myrtaceae . Intraspecific variability in pathogenicity has been ...reported among isolates of A . psidii from different hosts. However, there are few studies that have comparatively quantified the disease in guava ( Psidium guajava ) and rose apple ( Syzygium jambos ). The objective of this work was to quantify the pathogenic variability of A . psidii isolates collected from guava and rose apple in Brazil and to investigate the mechanisms of infection and colonization of the pathogen at the cellular level. The monocyclic components of the rust disease were evaluated on young leaves of rose apple and guava plants cross‐inoculated with isolates from rose apple and guava. Pathogenic specialization of both A . psidii isolates for their respective hosts was confirmed in this work. The guava A . psidii isolate was able to infect and colonize rose apple leaf tissues but no sporulation occurred. Similarly, the rose apple A . psidii isolate infected guava plants but did not sporulate. Confocal laser scanning microscopy revealed that lobed haustoria were present within rose apple leaves at 2 days post‐inoculation (dpi) with both isolates, which resulted in intense mesophyll colonization for both interactions at 9 dpi. The latter is remarkable because infection of rose apple with the guava A . psidii isolate did not result in mature rust pustules.
Colletotrichum is one of the most important plant pathogenic genus of fungi due to its scientific and economic impact. A wide range of hosts can be infected by Colletotrichum spp., which causes ...losses in crops of major importance worldwide, such as soybean. Soybean anthracnose is mainly caused by C. truncatum, but other species have been identified at an increasing rate during the last decade, becoming one of the most important limiting factors to soybean production in several regions. To gain a better understanding of the evolutionary origin of soybean anthracnose, we compared the repertoire of effector candidates of four Colletotrichum species pathogenic to soybean and eight species not pathogenic. Our results show that the four species infecting soybean belong to two lineages and do not share any effector candidates. These results strongly suggest that two Colletotrichum lineages have acquired the capability to infect soybean independently. This study also provides, for each lineage, a set of candidate effectors encoding genes that may have important roles in pathogenicity towards soybean offering a new resource useful for further research on soybean anthracnose management.
Context.
We present results from the first recorded stellar occultation by the large trans-Neptunian object (174567) Varda that was observed on September 10, 2018. Varda belongs to the ...high-inclination dynamically excited population, and has a satellite, Ilmarë, which is half the size of Varda.
Aims.
We determine the size and albedo of Varda and constrain its 3D shape and density.
Methods.
Thirteen different sites in the USA monitored the event, five of which detected an occultation by the main body. A best-fitting ellipse to the occultation chords provides the instantaneous limb of the body, from which the geometric albedo is computed. The size and shape of Varda are evaluated, and its bulk density is constrained using Varda’s mass as is known from previous works.
Results.
The best-fitting elliptical limb has semi-major (equatorial) axis of (383 ± 3) km and an apparent oblateness of 0.066 ± 0.047, corresponding to an apparent area-equivalent radius
R
′
equiv
= (370±7) km and geometric albedo
p
v
= 0.099 ± 0.002 assuming a visual absolute magnitude
H
V
= 3.81 ± 0.01. Using three possible rotational periods for the body (4.76, 5.91, and 7.87 h), we derive corresponding MacLaurin solutions. Furthermore, given the low-amplitude (0.06 ± 0.01) mag of the single-peaked rotational light-curve for the aforementioned periods, we consider the double periods. For the 5.91 h period (the most probable) and its double (11.82 h), we find bulk densities and true oblateness of
ρ
= (1.78 ± 0.06) g cm
−3
,
ɛ
= 0.235 ± 0.050, and
ρ
= (1.23 ± 0.04) g cm
−3
,
ɛ
= 0.080 ± 0.049. However, it must be noted that the other solutions cannot be excluded just yet.
Context. Bright stellar positions are now known with an uncertainty below 1 mas thanks to Gaia DR2. Between 2019–2020, the Galactic plane will be the background of Jupiter. The dense stellar ...background will lead to an increase in the number of occultations, while the Gaia DR2 catalogue will reduce the prediction uncertainties for the shadow path. Aims. We observed a stellar occultation by the Galilean moon Europa (J2) and propose a campaign for observing stellar occultations for all Galilean moons. Methods. During a predicted period of time, we measured the light flux of the occulted star and the object to determine the time when the flux dropped with respect to one or more reference stars, and the time that it rose again for each observational station. The chords obtained from these observations allowed us to determine apparent sizes, oblatness, and positions with kilometre accuracy. Results. We present results obtained from the first stellar occultation by the Galilean moon Europa observed on 2017 March 31. The apparent fitted ellipse presents an equivalent radius of 1561.2 ± 3.6 km and oblatenesses 0.0010 ± 0.0028. A very precise Europa position was determined with an uncertainty of 0.8 mas. We also present prospects for a campaign to observe the future events that will occur between 2019 and 2021 for all Galilean moons. Conclusions. Stellar occultation is a suitable technique for obtaining physical parameters and highly accurate positions of bright satellites close to their primary. A number of successful events can render the 3D shapes of the Galilean moons with high accuracy. We encourage the observational community (amateurs included) to observe the future predicted events.
Soybean (Glycine max) is one of the most important cultivated plants worldwide as a source of protein‐rich foods and animal feeds. Anthracnose, caused by different lineages of the hemibiotrophic ...fungus Colletotrichum, is one of the main limiting factors to soybean production. Losses due to anthracnose have been neglected, but their impact may threaten up to 50% of the grain production.
Taxonomy
While C. truncatum is considered the main species associated with soybean anthracnose, recently other species have been reported as pathogenic on this host. Until now, it has not been clear whether the association of new Colletotrichum species with the disease is related to emerging species or whether it is due to the undergoing changes in the taxonomy of the genus.
Disease symptoms
Typical anthracnose symptoms are pre‐ and postemergence damping‐off; dark, depressed, and irregular spots on cotyledons, stems, petioles, and pods; and necrotic laminar veins on leaves that can result in premature defoliation. Symptoms may evolve to pod rot, immature opening of pods, and premature germination of grains.
Challenges
As accurate species identification of the causal agent is decisive for disease control and prevention, in this work we review the taxonomic designation of Colletotrichum isolated from soybean to understand which lineages are pathogenic on this host. We also present a comprehensive literature review of soybean anthracnose, focusing on distribution, symptomatology, epidemiology, disease management, identification, and diagnosis. We consider the knowledge emerging from population studies and comparative genomics of Colletotrichum spp. associated with soybean providing future perspectives in the identification of molecular factors involved in the pathogenicity process.
Useful website
Updates on Colletotrichum can be found at http://www.colletotrichum.org/.
All available Colletotrichum genomes on GenBank can be viewed at http://www.colletotrichum.org/genomics/.
A revision of soybean anthracnose revealed that along with Colletotrichum truncatum, several other species of Colletotrichum are associated with soybean worldwide, revealing a knowledge gap in what we know about this disease so far.
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