scholarly journals Liberibacter, A Preemptive Bacterium: Apoptotic Response Repression in the Host Gut at the Early Infection to Facilitate Its Acquisition and Transmission

2020 ◽  
Vol 11 ◽  
Author(s):  
Xiao-Tian Tang ◽  
Kelsy Fortuna ◽  
Azucena Mendoza Herrera ◽  
Cecilia Tamborindeguy

“Candidatus Liberibacter solanacearum” (Lso) is a phloem-limited Gram-negative bacterium that infects crops worldwide. In North America, two haplotypes of Lso (LsoA and LsoB) are transmitted by the potato psyllid, Bactericera cockerelli (Šulc), in a circulative and persistent manner. Both haplotypes cause damaging plant diseases (e.g., zebra chip in potatoes). The psyllid gut is the first organ Lso encounters and could be a barrier for its transmission. However, little is known about the psyllid gut immune responses triggered upon Lso infection. In this study, we focused on the apoptotic response in the gut of adult potato psyllids at the early stage of Lso infection. We found that there was no evidence of apoptosis induced in the gut of the adult potato psyllids upon infection with either Lso haplotype based on microscopic observations. However, the expression of the inhibitor of apoptosis IAPP5.2 gene (survivin-like) was significantly upregulated during the period that Lso translocated into the gut cells. Interestingly, silencing of IAPP5.2 gene significantly upregulated the expression of two effector caspases and induced apoptosis in the psyllid gut cells. Moreover, RNA interference (RNAi) of IAPP5.2 significantly decreased the Lso titer in the gut of adult psyllids and reduced their transmission efficiency. Taken together, these observations suggest that Lso might repress the apoptotic response in the psyllid guts by inducing the anti-apoptotic gene IAPP5.2 at an early stage of the infection, which may favor Lso acquisition in the gut cells and facilitate its transmission by potato psyllid.

2010 ◽  
Vol 11 (1) ◽  
pp. 33 ◽  
Author(s):  
James M. Crosslin ◽  
Joseph E. Munyaneza ◽  
Judith K. Brown ◽  
Lia W. Liefting

Potato zebra chip (ZC) disease is a relative newcomer to the world of important potato diseases. First reported in Mexico in the 1990s, by 2004-2005 the disease was causing serious economic damage in parts of Texas. ZC is now widespread in the south-western and central United States, Mexico, Central America, and was recently reported in New Zealand. By 2006, there seemed to be an association between ZC and the potato psyllid (Bactericera cockerelli). The exact nature of the relationship, however, has only recently been identified by the discovery of a new Candidatus Liberibacter bacterium that is transmitted to potatoes, tomatoes, and other solanaceous hosts by the potato psyllid. This review examines the history of this disease, the association of ZC with the potato psyllid, the host range, and recent research into the bacterial pathogen. Accepted for publication 15 December 2009. Published 17 March 2010.


2020 ◽  
Vol 113 (6) ◽  
pp. 2595-2603
Author(s):  
Cesar A Reyes Corral ◽  
W Rodney Cooper ◽  
David R Horton ◽  
Alexander V Karasev

Abstract The potato psyllid, Bactericera cockerelli (Šulc), is a major pest of potato (Solanum tuberosum L.; Solanales: Solanaceae) as a vector of ‘Candidatus Liberibacter solanacearum’, the pathogen that causes zebra chip. Management of zebra chip is challenging in part because the noncrop sources of Liberibacter-infected psyllids arriving in potato remain unknown. Adding to this challenge is the occurrence of distinct genetic haplotypes of both potato psyllid and Liberibacter that differ in host range. Longleaf groundcherry (Physalis longifolia Nutt.) has been substantially overlooked in prior research as a potential noncrop source of Liberibacter-infected B. cockerelli colonizing fields of potato. The objective of this study was to assess the suitability of P. longifolia to the three common haplotypes of B. cockerelli (central, western, and northwestern haplotypes), and to two haplotypes of ‘Ca. L. solanacearum’ (Liberibacter A and B haplotypes). Greenhouse bioassays indicated that B. cockerelli of all three haplotypes produced more offspring on P. longifolia than on potato and preferred P. longifolia over potato during settling and egg-laying activities. Greenhouse and field trials showed that P. longifolia was also highly susceptible to Liberibacter. Additionally, we discovered that infected rhizomes survived winter and produced infected plants in late spring that could then be available for psyllid colonization and pathogen acquisition. Results show that P. longifolia is susceptible to both B. cockerelli and ‘Ca. L. solanacearum’ and must be considered as a potentially important source of infective B. cockerelli colonizing potato fields in the western United States.


Plant Disease ◽  
2019 ◽  
Vol 103 (10) ◽  
pp. 2587-2591 ◽  
Author(s):  
Jennifer Dahan ◽  
Erik J. Wenninger ◽  
Brandon D. Thompson ◽  
Sahar Eid ◽  
Nora Olsen ◽  
...  

‘Candidatus Liberibacter solanacearum’ (Lso) is an uncultured, phloem-associated bacterium causing a severe tuber disease in potato called zebra chip (ZC). Seven haplotypes of Lso have been described in different hosts, with haplotypes A and B found associated with infections in potato and tomato. In the field, Lso is transmitted by the potato psyllid (Bactericera cockerelli), and between 2011 and 2015, a significant change in Lso haplotype prevalence was previously reported in Idaho: from exclusively A haplotype found in tested psyllids in 2012 to mainly B haplotype found in collected psyllids in 2015. However, prevalence of Lso haplotypes in Idaho was not analyzed in potato tubers exhibiting symptoms of ZC. To fill in this knowledge gap, prevalence of Lso haplotypes was investigated in potato tubers harvested in southern Idaho between 2012 and 2018, and it was found to change from exclusively A haplotype in the 2012 season to an almost equal A and B haplotype distribution during the 2016 season. During the same period, haplotype distribution of Lso in psyllid vectors collected using yellow sticky traps also changed, but in psyllids, the shift from A haplotype of Lso to B haplotype was complete, with no A haplotype detected in 2016 to 2018. The changes in the haplotype prevalence of the Lso circulating in potato fields in southern Idaho may be, among other factors, responsible for a decrease in the ZC incidence in Idaho potato fields between an outbreak of the disease in 2012 and a very low level of ZC afterward.


2019 ◽  
Vol 88 (1) ◽  
Author(s):  
Xiao-Tian Tang ◽  
Cecilia Tamborindeguy

ABSTRACT “Candidatus Liberibacter solanacearum” is a pathogen transmitted by the potato psyllid Bactericera cockerelli (Šulc) (Hemiptera: Triozidae) in a persistent manner. In this study, we investigated the molecular interaction between “Ca. Liberibacter solanacearum” and the potato psyllid at the gut interface. Specifically, we focused on the apoptotic response of potato psyllids to the infection by two “Ca. Liberibacter solanacearum” haplotypes, LsoA and LsoB. To this end, we first quantified and localized “Ca. Liberibacter solanacearum” in the gut of adult psyllids. We then evaluated the existence of an apoptotic response in the insect gut using microscopy analyses to visualize the nuclei and the actin cytoskeleton of the gut cells and DNA fragmentation analyses by agarose gel electrophoresis. We also performed annexin V cell death assays to detect apoptosis. Finally, we annotated apoptosis-related genes from the potato psyllid transcriptome and evaluated their expression in response to “Ca. Liberibacter solanacearum” infection. The results showed no cellular markers of apoptosis despite the large amount of “Ca. Liberibacter solanacearum” present in the psyllid gut. In addition, only three genes potentially involved in apoptosis were regulated in the psyllid gut in response to “Ca. Liberibacter solanacearum”: the apoptosis-inducing factor AIF3 was downregulated in LsoA-infected psyllids, while the inhibitor of apoptosis IAPP5 was downregulated and IAP6 was upregulated in LsoB-infected psyllids. Overall, no evidence of apoptosis was observed in the gut of potato psyllid adults in response to either “Ca. Liberibacter solanacearum” haplotype. This study represents a first step toward understanding the interactions between “Ca. Liberibacter solanacearum” and the potato psyllid, which is crucial to developing approaches to disrupt their transmission.


Plant Disease ◽  
2017 ◽  
Vol 101 (5) ◽  
pp. 822-829 ◽  
Author(s):  
Jennifer Dahan ◽  
Erik J. Wenninger ◽  
Brandon Thompson ◽  
Sahar Eid ◽  
Nora Olsen ◽  
...  

Zebra chip (ZC) disease, a serious threat to the potato industry, is caused by the bacterium ‘Candidatus Liberibacter solanacearum’ (Lso). Five haplotypes (hapA to hapE) of this pathogen have been described so far in different crops, with only hapA and hapB being associated with ZC in potato. Both haplotypes are vectored and transmitted to a variety of solanaceaeous plants by the tomato/potato psyllid, Bactericera cockerelli (Šulc). Psyllids are native to North America, and four haplotypes have been identified and named based on their predominant geographic association: Northwestern, Central, Western, and Southwestern. Although all psyllid haplotypes have been found in southern Idaho potato fields, data on relative haplotype abundances and dynamic changes in the fields over time have not previously been reported. Here, psyllid samples collected in Idaho potato fields from 2012 to 2015 were used to clarify spatial and temporal patterns in distribution and abundance of psyllid and Lso haplotypes. A shift from hapA toward hapB population of Lso was revealed during these four seasons, indicating possible evolution of Lso in Idaho fields. Although we confirmed that Western psyllids were the most abundant by far during the four seasons of observation, we also observed changes in abundance of other haplotypes, including increased diversity of psyllid haplotypes during 2015. Seasonal changes observed for the Northwestern and Central haplotypes could potentially be linked to psyllid migration and/or habitat changes. South-central Idaho exhibited more diversity in psyllid haplotypes than southwestern Idaho.


Insects ◽  
2020 ◽  
Vol 11 (4) ◽  
pp. 243 ◽  
Author(s):  
Xiao-Tian Tang ◽  
Freddy Ibanez ◽  
Cecilia Tamborindeguy

Concanavalin A (ConA), a legume lectin, has been drawing increasing attention in recent years concerning its toxicity against insects and its potential application in pest management. In an attempt to evaluate the effect of ConA on potato psyllid (Bactericera cockerelli), an economically important pest of solanaceous crops, the effect of ConA on potato psyllid survival, psyllid gut nuclear morphology, and expression of psyllid caspase genes were evaluated. Our results determined that artificial diet-feeding assays using ConA had deleterious effects on potato psyllids, resulting in significant psyllid mortality following ingestion. We also found that an apoptotic response was induced by ConA in psyllid midgut cells, which was demonstrated by the DNA fragmentation and abnormal nuclear architecture in the midgut cells. Following ConA ingestion, there was also upregulation of caspase genes in the psyllid midguts. Therefore, a key mechanism behind ConA toxicity towards potato psyllid probably involves the induction of apoptosis in midgut cells. This study could provide a better understanding of the mechanisms underlying ConA toxicity in insects and be a stepping stone towards the development of new psyllid control strategies based on plant lectins.


2011 ◽  
Vol 62 (5) ◽  
pp. 1510-1520 ◽  
Author(s):  
Punya Nachappa ◽  
Julien Levy ◽  
Elizabeth Pierson ◽  
Cecilia Tamborindeguy

2012 ◽  
Vol 102 (11) ◽  
pp. 1079-1085 ◽  
Author(s):  
A. Rashed ◽  
T. D. Nash ◽  
L. Paetzold ◽  
F. Workneh ◽  
C. M. Rush

With diseases caused by vector-borne plant pathogens, acquisition and inoculation are two primary stages of the transmission, which can determine vector efficiency in spreading the pathogen. The present study was initiated to quantify acquisition and inoculation successes of ‘Candidatus Liberibacter solanacearum’, the etiological agent of zebra chip disease of potato, by its psyllid vector, Bactericera cockerelli (Hemiptera: Triozidae). Acquisition success was evaluated in relation to feeding site on the host plant as well as the acquisition access period. Inoculation success was evaluated in relation to vector number (1 and 4) on the plants. Acquisition success was influenced by the feeding site on the plant. The highest acquisition success occurred when insects had access to the whole plant. The results of the inoculation study indicated that the rate of successfully inoculated plants increased with the vector number. Plants inoculated with multiple psyllids had higher bacterial titer at the point of inoculation. Although disease incubation period was significantly shorter in plants inoculated with multiple psyllids, this effect was heterogeneous across experimental blocks, and was independent of pathogen quantity detected in the leaflets 3 days postinoculation. Disease progress was not affected by bacterial quantity injected or psyllid numbers.


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