scholarly journals Enemy or ally: a genomic approach to elucidate the lifestyle of Phyllosticta citrichinaensis

2021 ◽  
Author(s):  
Valerie Amber Buijs ◽  
Johannes Z. Groenewald ◽  
Sajeet Haridas ◽  
Kurt LaButti ◽  
Anna Lipzen ◽  
...  
Keyword(s):  
Citrus Sinensis ◽  
Black Spot ◽  
Economic Losses ◽  
Citrus Limon ◽  
Carbohydrate Active Enzymes ◽  
Genomic Comparison ◽  
Citrus Black Spot ◽  
Genomic Approach ◽  
Citrus Maxima ◽  
Fungal Genus

Members of the fungal genus Phyllosticta can colonize a variety of plant hosts, including several Citrus species such as Citrus sinensis (orange), Citrus limon (lemon), and Citrus maxima (pomelo). Some Phyllosticta species have the capacity to cause disease, such as Citrus Black Spot, while others have only been observed as endophytes. Thus far, genomic differences underlying lifestyle adaptations of Phyllosticta species have not yet been studied. Furthermore, the lifestyle of Phyllosticta citrichinaensis is ambiguous, as it has been described as a weak pathogen but Kochs postulates may not have been established and the presence of this species was never reported to cause any crop or economic losses. Here, we examined the genomic differences between pathogenic and endophytic Phyllosticta spp. colonizing Citrus and specifically aimed to elucidate the lifestyle of Phyllosticta citrichinaensis. We found several genomic differences between species of different lifestyles, including groups of genes that were only present in pathogens or endophytes. We also observed that species, based on their carbohydrate active enzymes, group independent of their phylogenetic association, and this clustering correlated with trophy prediction. Phyllosticta citrichinaensis shows an intermediate lifestyle, sharing genomic and phenotypic attributes of both pathogens and endophytes. We thus present the first genomic comparison of multiple citrus-colonizing pathogens and endophytes of the genus Phyllosticta, and therefore provide the basis for further comparative studies into the lifestyle adaptations within this genus.

scholarly journals Inoculum Dynamics and Infection of Citrus Fruit by Phyllosticta citricarpa

2020 ◽  
Vol 110 (10) ◽  
pp. 1680-1692
Author(s):  
Nga T. Tran ◽  
Andrew K. Miles ◽  
Ralf G. Dietzgen ◽  
Timothy A. Shuey ◽  
Stephen R. Mudge ◽  
...  
Keyword(s):  
Leaf Litter ◽  
Disease Incidence ◽  
Citrus Fruit ◽  
Black Spot ◽  
Summer Rainfall ◽  
Tree Canopy ◽  
Economic Losses ◽  
Citrus Black Spot ◽  
Spore Trapping ◽  
Phyllosticta Citricarpa

Citrus black spot, caused by Phyllosticta citricarpa, is characterized by fruit blemishes and premature fruit drop, resulting in significant economic losses in summer rainfall areas. The pathogen forms both conidia and ascospores during its life cycle. However, the occurrence of these spores and their contributions to infection of fruit in field conditions are not well understood. Our research using direct leaf litter monitoring and volumetric spore trapping in Queensland orchards revealed that pseudothecia and ascospores in leaf litter as well as trapped ascospores had low abundance, while pycnidia and conidia were highly abundant. Both P. citricarpa and endophytic Phyllosticta spp. were identified, with P. citricarpa being dominant. In replicated field trials, we determined that infection of Imperial mandarin fruit by P. citricarpa occurred from fruit set until week 20 of fruit development, with the key infection events taking place between weeks 4 and 16 in Queensland subtropical conditions. These results demonstrate that protecting fruit during weeks 4 to 16 significantly reduced P. citricarpa infection. We found no significant correlation between the disease incidence in fruit and P. citricarpa conidial abundance in leaf litter or ascospore abundance measured by volumetric spore trapping. Therefore, it is suggested that inoculum sources in the tree canopy other than those detected by spore trapping and direct leaf litter monitoring may play a major role in the epidemiology of citrus black spot. Improved knowledge regarding epidemiology of P. citricarpa and an understanding of propagules causing infection may aid in development of more effective disease management strategies.

scholarly journals First report of Xanthomonas citri Subsp. Citri causing citrus canker on grape fruit (Citrus paradisi), washington naval (Citrus sinensis), kaghzi limon (Citrus aurantifolia Swingle), lemon (Citrus lim

2021 ◽  
Vol 58 (04) ◽  
pp. 1373-1377
Author(s):  
Muhammad Shah Nawaz ul Rehman
Keyword(s):  
Citrus Sinensis ◽  
Sequence Similarity ◽  
Citrus Canker ◽  
Citrus Limon ◽  
Evolutionary Analysis ◽  
Citrus Paradisi ◽  
Xanthomonas Citri ◽  
Citrus Aurantifolia ◽  
Grape Fruit ◽  
Citrus Maxima

Citrus fruit production is largely affected by different bacterial and fungal pathogens. In Pakistan bacterial diseases like citrus bacterial canker (CBC) pose severe risk to citrus economy. Diagnoses of such diseases could be helpful to avoid the epidemics in nurseries or orchids. In 2011-12, citrus canker symptoms i.e., callus-like outgrowths on leaves and fruits of grape fruit (Citrus paradisi), Washington naval (Citrus sinensis), Kaghzi Limon (Citrus aurantifolia swingle), lemon (Citrus Limon) and pomelo (Citrus maxima) were noticed in Sargodha district of Punjab, Pakistan. Bacteria i.e., yellow mucoid, Xanthomonas- like isolates, were isolated from these lesions. Bacteria isolated from these lesions were cultured and total DNA was isolated. A diagnostic fragment of 581 bp based on rpf genes of Xanthomonas citri pv. citri was amplified, cloned and completely sequenced. BLAST and evolutionary analysis revealed that these isolates show 100% sequence similarity and group with Xanthomonas citri subsp. citri from Argentina (CP023285) and Reunion (CP018858), (CP018854). To our knowledge, this is the first formal report of X. campestris pv. citri pathotypes A on Citrus paradise, Citrus sinensis, Citrus maxima, Citrus Limon and Citrus aurantifolia swingle in Pakistan

scholarly journals Sexual Reproduction in the Citrus Black Spot Pathogen, Phyllosticta citricarpa

2017 ◽  
Vol 107 (6) ◽  
pp. 732-739 ◽  
Author(s):  
Nga T. Tran ◽  
Andrew K. Miles ◽  
Ralf G. Dietzgen ◽  
Megan M. Dewdney ◽  
Ke Zhang ◽  
...  
Keyword(s):  
Sexual Reproduction ◽  
Culture Media ◽  
Black Spot ◽  
Physical Contact ◽  
Sexual Cycle ◽  
Economic Losses ◽  
Type Locus ◽  
Citrus Black Spot ◽  
Phyllosticta Citricarpa ◽  
The Impact

Citrus black spot (Phyllosticta citricarpa) causes fruit blemishes and premature fruit drop, resulting in significant economic losses in citrus growing areas with summer rainfall across the globe. The mating type locus of P. citricarpa has recently been characterized, revealing the heterothallic nature of this pathogen. However, insight into the occurrence of mating and the impact of completing the sexual cycle of P. citricarpa was lacking. To investigate the occurrence and impact of sexual reproduction, we developed a method to reliably, and for the first time, produce ascospores of P. citricarpa on culture media. To demonstrate meiosis during the mating process, we identified recombinant genotypes through multilocus genotyping of single ascospores. Because the process of fertilization was not well understood, we experimentally determined that fertilization of P. citricarpa occurs via spermatization. Our results demonstrate that P. citricarpa is heterothallic and requires isolates of different MAT idiomorphs to be in direct physical contact, or for spermatia to fulfill their role as male elements to fertilize the receptive organs, in order to initiate the mating process. The impact of mating on the epidemiology of citrus black spot in the field is discussed.

scholarly journals First report of citrus black spot disease caused by Phyllosticta citricarpa on Citrus limon and C. sinensis in Tunisia

2020 ◽  
Vol 41 ◽  
pp. 8 ◽  
Author(s):  
N. Boughalleb-M’Hamdi ◽  
A. Fathallah ◽  
N. Benfradj ◽  
S. Ben Mahmoud ◽  
A. Bel Hadj Ali ◽  
...  
Keyword(s):  
Black Spot ◽  
Citrus Limon ◽  
First Report ◽  
Spot Disease ◽  
Citrus Black Spot ◽  
Phyllosticta Citricarpa ◽  
Black Spot Disease

scholarly journals Identification of Resistance to Citrus Black Spot Using a Novel In-field Inoculation Assay

HortScience ◽  
2019 ◽  
Vol 54 (10) ◽  
pp. 1673-1681 ◽  
Author(s):  
Andrew K. Miles ◽  
Malcolm W. Smith ◽  
Nga T. Tran ◽  
Timothy A. Shuey ◽  
Megan M. Dewdney ◽  
...  
Keyword(s):  
Black Spot ◽  
Preliminary Evidence ◽  
Field Inoculation ◽  
Citrus Black Spot ◽  
Citrus Breeding ◽  
Fruit Drop ◽  
Citrus Maxima ◽  
Phyllosticta Citricarpa ◽  
Production Areas ◽  
And Control

Citrus black spot is an important fungal disease of citrus resulting in fruit drop and rind blemish in tropical and subtropical production areas. The disease is incited by the fungus Phyllosticta citricarpa (McAlpine) van der Aa (synonym: Guignardia citricarpa Kiely), with control currently relying on the application of fungicides. Because the presence and expression of resistance is poorly understood, we sought to develop a method for inoculating fruit in the field that gives reproducible symptoms of citrus black spot consistent with natural field infection. We subsequently validated this method by screening 49 citrus accessions and characterized their qualitative expression of citrus black spot symptoms. Challenge inoculations were undertaken with a known isolate of P. citricarpa, and control fruit were inoculated with water or the endophyte P. paracapitalensis Guarnaccia & Crous. Our results showed that all mandarin, sweet orange, lemon and papeda types were susceptible; pummelo, lime, and sour orange types expressed immunity; while various hybrids were susceptible, resistant and immune. Hybrid progeny from crosses using pummelo [Citrus maxima (Burm.) Merr.] as a parent showed preliminary evidence of segregation for citrus black spot immunity. The implications of these results to achieve genetic improvement for citrus black spot resistance in citrus breeding programs are discussed.

scholarly journals Nonpathogenic Isolates of the Citrus Black Spot Fungus, Guignardia citricarpa, Identified as a Cosmopolitan Endophyte of Woody Plants, G. mangiferae (Phyllosticta capitalensis)

2002 ◽  
Vol 92 (5) ◽  
pp. 464-477 ◽  
Author(s):  
R. P. Baayen ◽  
P. J. M. Bonants ◽  
G. Verkley ◽  
G. C. Carroll ◽  
H. A. van der Aa ◽  
...  
Keyword(s):  
United States ◽  
European Union ◽  
Woody Plants ◽  
Black Spot ◽  
The United States ◽  
The European Union ◽  
Citrus Fruits ◽  
Citrus Black Spot ◽  
Group I ◽  
Group Ii

The population structure of Guignardia citricarpa sensu lato (anamorph: Phyllosticta citricarpa), a fungus of which strains pathogenic to citrus are subject to phytosanitary legislation in the European Union and the United States, was investigated. Internal transcribed spacer sequences revealed two phylogenetically distinct groups in G. citricarpa. This distinction was supported by amplified fragment length polymorphism analysis that also supported the exclusion of two isolates that had apparently been misclassified as G. citricarpa. On cherry decoction agar, but not on other media, growth rates of group I isolates were lower than those of group II isolates. Conidial dimensions were similar, but group I isolates formed conidia with barely visible mucoid sheaths, whereas those of group II formed conidia with thick sheaths. Cultures of isolates belonging to group I produced rare infertile perithecia, whereas fertile perithecia were formed by most isolates of group II. Colonies of isolates belonging to group I were less dark than those of group II, with a wider translucent outer zone and a lobate rather than entire margin. On oatmeal agar, exclusively group I isolates formed a yellow pigment. Group I harbored strains from citrus fruits with classical black spot lesions (1 to 10 mm in diameter) usually containing pycnidia. Group II harbored endophytic strains from a wide range of host species, as well as strains from symptomless citrus fruits or fruits with minute spots (<2-mm diameter) without pycnidia. These observations support the historic distinction between slowly growing pathogenic isolates and morphologically similar fast-growing, nonpathogenic isolates of G. citricarpa. The latter proved to belong to G. mangiferae (P. capitalensis), a ubiquitous endophyte of woody plants with numerous probable synonyms including G. endophyllicola, G. psidii, P. anacardiacearum, and P. theacearum. G. mangiferae occurs in the European Union and the United States on many host species including citrus, and does not cause symptoms of citrus black spot, justifying its exclusion from quarantine measures.

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