, the pale cyst nematode (PCN), is a quarantine pest of potato posing a serious threat to the Idaho potato industry.
only hatches in the presence of a hatching stimulus produced by a host plant or ...closely related species. In the absence of this hatching stimulus,
can remain viable in the soil for decades. A trap crop stimulates hatch of
but is a nonhost, which means the nematode cannot develop or reproduce. This study evaluated the trap crop potential of several solanaceous species by determining
host status and hatching effect of each species. The species under investigation included
,
,
,
, and
. All species were determined to be nonhosts of
. The most promising trap crop candidates with a hatching stimulatory effect comparable to potato were
and
Further research is needed to assess whether these species could be effective
trap crops under Idaho field conditions.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Plant pathogens, such as bacteria, fungi, oomycetes and nematodes, rely on wide range of virulent effectors delivered into host cells to suppress plant immunity. Although phytobacterial effectors ...have been intensively investigated, little is known about the function of effectors of plant-parasitic nematodes, such as Globodera pallida, a cyst nematode responsible for vast losses in the potato and tomato industries. Here, we demonstrate using in vivo and in vitro ubiquitination assays the potato cyst nematode (Globodera pallida) effector RHA1B is an E3 ubiquitin ligase that employs multiple host plant E2 ubiquitin conjugation enzymes to catalyze ubiquitination. RHA1B was able to suppress effector-triggered immunity (ETI), as manifested by suppression of hypersensitive response (HR) mediated by a broad range of nucleotide-binding leucine-rich repeat (NB-LRR) immune receptors, presumably via E3-dependent degradation of the NB-LRR receptors. RHA1B also blocked the flg22-triggered expression of Acre31 and WRKY22, marker genes of pathogen-associated molecular pattern (PAMP)-triggered immunity (PTI), but this did not require the E3 activity of RHA1B. Moreover, transgenic potato overexpressing the RHA1B transgene exhibited enhanced susceptibility to G. pallida. Thus, our data suggest RHA1B facilitates nematode parasitism not only by triggering degradation of NB-LRR immune receptors to block ETI signaling but also by suppressing PTI signaling via an as yet unknown E3-independent mechanism.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
, the pale cyst nematode, is a regulated potato pest which is economically detrimental. Restrictions on use of the soil fumigant methyl bromide and lack of resistant russet type varieties for U.S. ...markets have led to investigations of alternative strategies to control this pest. The efficacy of
seed meal extract (SME; 0, 0.14, 0.28, 0.56, 1.12, and 2.24 t/ha) was studied, either alone or in combination with the trap crop
under greenhouse and field conditions. The impact of the application of SME pre- or postplanting of
was also determined.
only induced hatch of
and significantly fewer (up to 57 and 55% in pre- and postplant experiments, respectively) encysted eggs remained at termination of the experiment compared with the untreated control. However, when SME was applied preplant, the encysted eggs remained unchanged, which may indicate that SME inhibited egg hatch in the presence of
. When applied individually,
in all experiments, or SME at all rates tested in the greenhouse or 0.56 t/ha or higher rates of SME in the field, significantly reduced the viability, hatch, and reproduction of
. Combined treatment with
and SME at lower rates (0.14 t/ha for preplant or 0.56 t/ha or less for the greenhouse postplant experiment) reduced
egg hatch further than each strategy alone. In the field, a combination of
and SME at 1.12 t/ha or less reduced
more effectively than SME alone. SME alone applied at higher rates (0.56 and 1.12 t/ha) in preplant greenhouse trials, whether or not combined with
, eliminated
reproduction. Under field conditions, SME applied at a rate of 1.12 t/ha highly reduced
reproduction compared with the untreated control by 97 and 61% in 2019 and 2020, respectively. Furthermore, reproduction of
was eliminated when SME was combined with
. Our results indicated that a combination of SME and
reduces the amount of SME needed to control
and further decreases the potential reserve of the viable population remaining after individual treatment with each strategy.
Plants use pattern recognition receptors (PRRs) to perceive conserved molecular patterns derived from pathogens and pests, thereby activating a sequential set of rapid cellular immune responses, ...including activation of mitogen-activated protein kinases (MAPKs) and Ca2+-dependent protein kinases (CDPKs), transcriptional reprogramming (particularly the induction of defense-related genes), ion fluxes, and production of reactive oxygen species.1 Plant PRRs belong to the multi-membered protein families of receptor-like kinases (RLKs) or receptor-like proteins (RLPs). RLKs consist of a ligand-binding ectodomain, a single-pass transmembrane domain, and an intracellular kinase domain, while RLPs possess the same functional domains, except for the intracellular kinase domain.2 The most abundant nematode ascaroside, Ascr18, is a nematode-associated molecular pattern (NAMP) that induces immune signaling and enhances resistance to pathogens and pests in various plant species.3 In this study, we found that the Arabidopsis NEMATODE-INDUCED LRR-RLK1 (NILR1) protein4 physically interacts with the Ascr18 elicitor, as indicated by a specific direct interaction between NILR1 and Ascr18, and NILR1 is genetically required for Ascr18-triggered immune signaling and resistance to both bacterium and nematode, as manifested by the abolishment of these immune responses in the nilr1 mutant. These results suggest that NILR1 is the immune receptor of the nematode NAMP Ascr18, mediating Ascr18-triggered immune signaling and resistance to pathogens and pests.
•NILR1 specifically and directly binds to nematode pheromone ascaroside #18 (Ascr18)•NILR1 is required for Ascr18-triggered immune signaling in Arabidopsis•NILR1 is required for Ascr18-triggered resistance to bacterium and nematode
Huang et al. show that the plant pattern recognition receptor NILR1 recognizes a conserved nematode-associated molecular pattern Ascr18 to activate immune signaling and resistance to pathogens and pests. The Ascr18-NILR1 pair is the first example of ligand-receptor identified in the innate immunity in plants or animals against nematode infection.
Steroidal glycoalkaloids (SGAs) are phytoanticipins found in
crops that act as the first line of chemical defense against pathogen attacks.
, a trap crop for potato cyst nematodes, has been shown to ...effectively reduce populations of
.
.
contains α-solamargine and other solasodine-type glycoalkaloids that may contribute to plant defenses. This study evaluated the influence of
SGAs on
.
hatch, development, and reproduction. Exposure to α-solamargine and α-solamarine reduced
.
hatch by 65 and 87%, respectively. Exposure of
.
cysts with the glycoalkaloids α-solamargine and solasodine significantly reduced infection in susceptible potato 'Russet Burbank' by 98 and 94% compared with the control. Exposure of cysts to either solasodine or solamargine significantly reduced reproduction of
.
on 'Russet Burbank' by 99% compared with the control. The study demonstrated the deleterious effect of SGAs on
.
hatch, infection, and reproduction.
Potato cyst nematodes (PCN) are economically important pests with a worldwide distribution in all temperate regions where potatoes are grown. Because above ground symptoms are non-specific, and ...detection of cysts in the soil is determined by the intensity of sampling, infestations are frequently spread before they are recognised. PCN cysts are resilient and persistent; their cargo of eggs can remain viable for over two decades, and thus once introduced PCN are very difficult to eradicate. Various control methods have been proposed, with resistant varieties being a key environmentally friendly and effective component of an integrated management programme. Wild and landrace relatives of cultivated potato have provided a source of PCN resistance genes that have been used in breeding programmes with varying levels of success. Producing a PCN resistant variety requires concerted effort over many years before it reaches what can be the biggest hurdle-commercial acceptance. Recent advances in potato genomics have provided tools to rapidly map resistance genes and to develop molecular markers to aid selection during breeding. This review will focus on the translation of these opportunities into durably PCN resistant varieties.
Potato cyst nematode (PCN) cysts consist of heterogenous populations of eggs, juveniles, and eggshells that make manual sorting of individual life stages cumbersome. The number of viable PCN eggs is ...a major determinant of crop damage. An accurate high-throughput PCN egg viability assay is useful for developing effective management and eradication plans. In this study, we present a method for rapid and precise enumeration and sorting of PCN eggs and juveniles, along with an egg viability assessment by staining eggs with the fluorescent stain, acridine orange, and sorting with the Complex Object Parametric Analyzer and Sorter (COPAS) system, a large particle flow cytometer. Both size sorting and fluorescent sorting capabilities of the COPAS were explored. By using the COPAS, sorting efficiency for eggs and preparasitic second-stage juveniles (J2s) was 97.6 and 97.2%, respectively, with 99% recovery at a flow rate of 15 events/s. Purity of sorted live and dead eggs was 95.5 and 94.1%, respectively. Sorting of J2s by size indicated that 15 to 16.4% of
or
had an average body length of 436.1 ± 3.4 µm compared with an average size of 512.9 ± 4.4 µm for the majority of the J2 population for both species. A red autofluorescing J2 population was also identified through sorting. Sorting of eggs by flow cytometry did not significantly affect hatching (55.1 ± 1.2 and 53.9 ± 1.6%, respectively, for sorted or nonsorted eggs) or juvenile motility (91.3 ± 1.0 or 90.1 ± 1.1%, respectively), thus confirming that the method does not impair the biological activity of the nematode.
A transcriptome analysis of G. pallida juveniles collected from S. tuberosum or S. sisymbriifolium 24 h post infestation was performed to provide insights into the parasitic process of this nematode. ...A total of 41 G. pallida genes were found to be significantly differentially expressed when parasitizing the two plant species. Among this set, 12 were overexpressed when G. pallida was parasitizing S. tuberosum and 29 were overexpressed when parasitizing S. sisymbriifolium. Out of the 12 genes, three code for secretory proteins; one is homologous to effector gene Rbp-4, the second is an uncharacterized protein with a signal peptide sequence, and the third is an ortholog of a Globodera rostochiensis effector belonging to the 1106 effector family. Other overexpressed genes from G. pallida when parasitizing S. tuberosum were either unknown, associated with a stress or defense response, or associated with sex differentiation. Effector genes namely Eng-1, Cathepsin S-like cysteine protease, cellulase, and two unknown genes with secretory characteristics were over expressed when G. pallida was parasitizing S. sisymbriifolium relative to expression from S. tuberosum. Our findings provide insight into gene regulation of G. pallida while infecting either the trap crop S. sisymbriifolium or the susceptible host, S. tuberosum.
Potato cyst nematodes (PCNs), such as
and
, are some of the most agriculturally and economically important pests of potato. Upon nematode infection, a principal component of plant defense is the ...generation of the reactive oxygen species (ROSs). ROSs are highly toxic molecules that cause damage to pathogens and host alike. To infect the plant, nematodes protect themselves from ROSs by activating their own antioxidant processes and ROS scavenging enzymes. One of these enzymes is a superoxide dismutase (SOD; EC 1.15.1.1), which prevents cellular damage by catalyzing conversion of the superoxide radical (O
) to hydrogen peroxide (H
O
) and molecular oxygen (O
). We have isolated a putatively secreted isoform of a Cu-Zn SOD (
) from
and localized the expression of this gene in the posterior region of the nematode. Furthermore, we studied the expression of the
gene during early parasitic stages of infection (24 to 72 h) in the susceptible potato cultivar Desiree, the resistant potato cultivar Innovator, and an immune host,
. The
gene was significantly upregulated, regardless of the host type; however, the expression pattern differed between the susceptible and the resistant or immune hosts. This finding suggests that
gene is responding to infection in plant roots differently depending on whether the nematode is experiencing a compatible or an incompatible interaction.
PDF
