Mosaic Symptoms Research Articles

First report of squash vein yellowing virus naturally infecting butternut squash (Cucurbita moschata) in Texas.

Virus diseases are major constraints to the production of cucurbits in the Texas Lower Rio Grande Valley. In September 2020, a ~8.1 ha butternut squash (Cucurbita moschata) field in Hidalgo County, Texas, was observed with virus-like symptoms of vein yellowing, leaf curl, mosaic, and foliar chlorosis. The proportion of plants with virus-like symptoms in this field was estimated at 30% and seven samples (symptomatic = 5; non-symptomatic = 2) were collected randomly for virus diagnosis. Initially, equimolar mixtures of total nucleic acid extracts (Dellaporta et. al. 1983) from two symptomatic samples from this field and extracts from 12 additional symptomatic samples from six other fields across south and central Texas was used to generate one composite sample for diagnosis by high throughput sequencing (HTS). The TruSeq Stranded Total RNA with Ribo-Zero Plant Kit (Illumina) was used to construct cDNA library from the composite sample, which was then sequenced on the Illumina NextSeq 500 platform. More than 26 million single-end HTS reads (75 nt each) were obtained and their bioinformatic analyses (Al Rwahnih et al. 2018) revealed several virus-like contigs belonging to different species (data not shown). Among them, 6 contigs that ranged in length from 429 to 3,834 nt shared 96 to 100% identities with isolates of squash vein yellowing virus (SqVYV), genus Ipomovirus, family Potyviridae. To confirm the HTS results, total nucleic acid extracts from the cucurbit samples from all seven fields (n = 46) were used for cDNA synthesis with random hexamers and the PrimeScript 1st strand cDNA Synthesis Kit (Takara Bio). A 1-μL aliquot of cDNA was used in 12.5-μL PCR reaction volumes with PrimeSTAR GXL DNA Polymerase (Takara Bio) and two pairs of SqVYV-specific primers designed based on the HTS derived contigs. The primer pairs SqYVV-v4762: 5'-CTGGATTCTGCTGGAAGATCA & SqYVV-c5512: 5'-CCACCATTAAGGCCATCAAAC and SqYVV-v8478: 5'-TTTCTGGGCAAACAAACATGG & SqYVV-c9715: 5'-TTCAGCGACGTCAAGTGAG targeted ~0.75 kb and ~1.2 kb fragments of the cylindrical inclusion (CI) and the complete coat protein (CP) gene sequences of SqVYV, respectively. The expected DNA band sizes were obtained only from the five symptomatic butternut squash samples from the Hidalgo Co. field. Two amplicons per primer pair from two samples were cloned into pJET1.2/Blunt vector (Life Technologies) and bidirectionally Sanger sequenced, generating 753 nt partial CI specific sequences (MW584341-342) and 1,238 nt that encompassed the complete CP (MW584343-344) of SqVYV. In pairwise comparisons, the partial CI sequences shared 100% nt/aa identity with each other and 98-99% nt/aa identity with corresponding sequences of SqVYV isolate IL (KT721735). The CP cistron of TX isolates shared 100% nt/aa identity with each other and 90-98% nt (97-100% aa) identities with corresponding sequences of several SqVYV isolates in GenBank, with isolates IL (KT721735) and Florida (EU259611) being at the high and low spectrum of nt/aa identity values, respectively. This is the first report of SqVYV in Texas, naturally occurring in butternut squash. SqVYV was first discovered in Florida (Adkins et al. 2007) and subsequently reported from few other states in the U.S. (Adkins et al. 2013; Egel and Adkins 2007; Batuman et al. 2015), Puerto Rico (Acevedo et al. 2013), and locations around the world. The finding shows an expansion of the geographical range of SqVYV and adds to the repertoire of cucurbit-infecting viruses in Texas. Further studies are needed to determine the prevalence of SqVYV in Texas cucurbit fields and an assessment of their genetic diversity.

Molecular and biological characterization of soybean yellow mottle mosaic virus severe strain infecting soybean in India.

The online version contains supplementary material available at 10.1007/s13205-021-02925-2.

NATURAL INFECTION OF Tobacco mosaic virus ON BUTTERNUT SQUASH IN BALI, INDONESIA

Natural infection of Tobacco mosaic virus on butternut squash in Bali, Indonesia. Tobacco mosaic virus (TMV) was a newly emerging virus infecting cucumbers in Indonesia since 2017. The mosaic disease caused by TMV potentially caused yield loss cucumber in Java. In 2019, mosaic symptoms were observed in butternut squash plants in Bali and molecular detection using universal primer of Tobamovirus indicated the presence of TMV infection. Further research was conducted to determine molecular characteristics of TMV on butternut squash plants in Bali. Specific DNA bands of Tobamovirus were amplified using reverse transcription polymerase chain reaction method, followed by DNA sequencing. The DNA were successfully amplified from CP Tobamovirus using universal primers from several butternut squash samples, i.e. Denpasar, Gianyar, Buleleng, and Karangasem Districts. The homology analysis of nucleotide and amino acid sequences of TMV among isolates from Denpasar, Gianyar, Buleleng, and Karangasem Districts was ranged between 95.6 – 97.7% and 98.1 – 99.4%, respectively. This indicated that low genetic diversity of TMV among Bali isolates. The highest homology of corresponding sequences of TMV isolates from Denpasar, Gianyar, Buleleng, and Karangasem Districts was closely related to TMV Kediri-Indonesia isolate on cucumber plant. Correspondingly, the phylogenetic analysis showed that TMV Bali isolates were categorized into same cluster with Kediri-Indonesia isolates. This was the first report of TMV on butternut squash in Indonesia.

The Existence of Papaya ringspot virus-Papaya Strain on Cucumber in Gianyar, Bali

Yellow mosaic symptoms were identified from cucumber production systems in Gianyar and were similar to symptoms of PRSV infection. Further research was conducted to determine diseases incidence and molecular characteristic of PRSV. Ninety leaf samples were collected from Gianyar by purposive sampling and disease incidence calculations were based on symptoms in the field. Detection and identification were done using a RT-PCR with specific primers of CP PRSV-P, CP PRSV-W and DNA sequencing. Disease incidences in the fields ranged between 5.81–66.87%. Specific DNA band 470 bp was successfully amplified from several cucumber leaf samples collected from Ubud, Payangan, Tegallalang, Sukawati, Gianyar, and Blahbatuh; but no DNA were amplified from all samples when using CP PRSV-W specific primer. Nucleotide and amino acid analysis showed nucleotides homology to isolates from Ubud, Payangan, Tegallalang, Sukawati, Gianyar, and Blahbatuh, i.e. 98.9–99.5% and 99.1–100%, respectively. Results indicated that genetic variation of PRSV-P from Gianyar was low. Furthermore, the nucleotides homology of PRSV-P isolates from Ubud, Payangan, Tegallalang, Sukawati, Gianyar, and Blahbatuh were with PRSV-P isolates which infected cucumbers from Nganjuk (LC311783) and Brebes (LC311784), while from native papaya collected in Bali Bali (LC223115) were 97.2–98.4% and 98.6–100%, respectively. Phylogenetic analysis confirmed that PRSV-P isolates from Indonesia were in the same cluster with Thailand isolates. The results showed that sources of PRSV-P inoculums spreading into new areas.

Molecular characterization and pathogenicity of an infectious cDNA clone of tomato brown rugose fruit virus

Tomato brown rugose fruit virus (ToBRFV) is a new member of the genus Tobamovirus, and has the potential to affect the production and marketability of tomatoes and peppers. In this study, we sequenced and analyzed the complete genome of ToBRFV isolates from tomato plants showing mosaic and mottling symptoms in Yunnan Province of China. We constructed a full-length infectious cDNA clone of ToBRFV, which could induce systemic infection with typical symptoms in tomato, Nicotiana benthamiana, and N. tabacum cv. Samsun nn plants through Agrobacterium-mediated inoculation. Further experimental evidence demonstrated that the rod-shaped virions accumulating in agroinfiltrated plants are sap-transmissible. This is the first report on the construction of a biologically active, full-length infectious cDNA clone of ToBRFV. The system developed herein will facilitate further research on functions of ToBRFV-encoded proteins and plant-ToBRFV interactions through reverse genetic approaches.

First Report of Tomato Spotted Wilt Virus in Angelica acutiloba

In June 2019, Angelica acutiloba plants showing virus-like symptoms such as chlorotic local lesion and mosaic on the leaves were found in a greenhouse in Nonsan, South Korea. To identify the causal virus, we collected 6 symptomatic A. acutiloba leaf samples and performed reverse transcription polymerase chain reaction (RT-PCR) analysis using specific detection primers for three reported viruses including tomato spotted wilt virus (TSWV). RT-PCR results showed that five symptomatic samples were positive for TSWV. Mechanical sap inoculation of one of the collected TSWV isolate (TSWV-NS-AG28) induced yellowing, chlorosis and mosaic symptoms in A. acutiloba and necrotic local lesions and mosaic in Solanaceae species. Phylogenetic analysis based on the complete genome sequences showed that TSWV-NS-AG28 had a maximum nucleotide identity with TSWV-NS-BB20 isolated from butterbur in Nonsan, South Korea. To our knowledge, this is the first report of TSWV infection in A. acutiloba.

Metagenomic Analysis of Marigold: Mixed Infection Including Two New Viruses.

Marigold plants with symptoms of mosaic, crinkle, leaf curl and necrosis were observed and small RNA and ribo-depleted total RNA deep sequencing were conducted to identify the associated viruses. Broad bean wilt virus 2, cucumber mosaic virus, turnip mosaic virus, a new potyvirus tentatively named marigold mosaic virus (MMV) and a new partitivirus named as marigold cryptic virus (MCV) were finally identified. Complete genome sequence analysis showed MMV was 9811 nt in length, encoding a large polyprotein with highest aa sequence identity (57%) with the putative potyvirus polygonatumkingianum virus 1. Phylogenetic analysis with the definite potyviruses based on the polyprotein sequence showed MMV clustered closest to plum pox virus. The complete genome of MCV comprised of dsRNA1 (1583 bp) and dsRNA2 (1459 bp), encoding the RNA-dependent RNA polymerase (RdRp), and coat protein (CP), respectively. MCV RdRp shared the highest (75.7%) aa sequence identity with the unclassified partitivirus ambrosia cryptic virus 2, and 59.0%, 57.1%, 56.1%, 54.5% and 33.7% with the corresponding region of the definite delta-partitiviruses, pepper cryptic virus 2, beet cryptic virus 3, beet cryptic virus 2, pepper cryptic virus 1 and fig cryptic virus, respectively. Phylogenetic analysis based on the RdRp aa sequence showed MCV clustered into the delta-partitivirus group. These findings enriched our knowledge of viruses infecting marigold, but the association of the observed symptom and the identified viruses and the biological characterization of the new viruses should be further investigated.

Distinguishing resistances of transgenic sugarcane generated from RNA interference and pathogen‐derived resistance approaches to combating sugarcane mosaic virus

Sugarcane mosaic virus (SCMV) is a causative agent that reduces growth and productivity in sugarcane. Pathogen‐derived resistance (PDR) and RNA interference (RNAi) are the most common approaches to generating resis‐ tance against plant viruses. Two types of transgenic sugarcane have been obtained by PDR and RNAi methods using a gene‐encoding coat protein (CP) of SCMV (SCMVCp). This research aimed to distinguish resistance of the two transgenic sugarcanes in combating SCMV through artificial viral inoculation. The experiment was conducted using transgenic sugar‐ cane lines validated by PCR analysis. Insertion of gene‐encoding CP in the transgenic lines was confirmed by amplification of 702 bp of DNA fragment of SCMVCp. After viral inoculation, mosaic symptoms appeared earlier, at 21 days post inoculation (dpi) in PDR transgenic lines, but was at 26 dpi in RNAi transgenic lines. Symptom observation showed that 77.8% and 50% of the inoculated plants developed mosaic symptoms in PDR and RNAi transgenic lines, respectively. RT‐PCR analysis revealed that the nuclear inclusion protein b (Nib) gene of SCMV was amplified in the symptomatic leaves in plants classified as susceptible lines. Immunoblot analysis confirmed presence of viral CP with a molecular size of 37 kDa in the susceptible lines. Collectively, these results indicated that the RNAi approach targeting the gene for CP effectively produces more resistance against the SCMV infection in transgenic sugarcane compared to the PDR approach.

Occurrence, Distribution and Identification of Viruses Infecting Some Cucurbits Across Major Cucurbit-Growing Areas in Cross River State, Nigeria

Cucurbits are group of plants which belonged in the Cucurbitaceae family and constitute one of the most important vegetables for human consumption throughout the world. A survey conducted between January to March 2021 across major cucurbit-growing area in Cross River State revealed wide spread virus infection of these crops, surveyed plants showed mosaic, mottle and leaf deformation symptoms. This research was aimed at identifying viruses infecting some cucurbits in the study areas. Twenty four samples showing virus like symptoms were collected and tested against ACP-ELISA and RT-PCR. Result obtained from ACP-ELISA showed that 20 out of 24 samples collected tested positive to universal potyvirus antisera, the gene sequence analysis revealed that samples were predominantly infected with Algerian watermelon mosaic virus representing 40% of total viruses detected followed by Morroccan watermelon mosaic virus representing 15% of total viruses detected followed by Papaya ringspot virus, Zucchini tigre mosaic virus, Watermelon mosaic virus and Soybean mosaic virus representing 10% each for total viruses detected and finally Potato virus Y representing 5% of total virus detected. This survey is an accurate and timely detection and will form the basis for mitigating yield losses resulting from virus infection on cucurbits. This is the first report of wide scale detection of viruses infecting cucurbits in Nigeria.

Complete genome sequence of hollyhock vein yellowing virus, a novel monopartite begomovirus infecting hollyhock in Pakistan.

Hollyhock (Alcea rosea, family Malvaceae) is an ornamental plant grown widely in gardens across South Asia. In a bed of ornamental plants near the village of Chakri (Punjab Province, Pakistan) in 2014, hollyhock plants showing two distinct symptom types were identified: yellow vein mosaic and leaf crumple. PCR amplification with universal primers amplified a begomovirus from separate nucleic acid extracts of single plants of each type but amplified a betasatellite only from the plant with the yellow vein mosaic symptoms. No potential begomovirus DNA B component or alphasatellite could be identified in either sample. After cloning, the genome sequences of two viruses, one from a plant of each symptom type, were determined and shown to share 99.9% nucleotide sequence identity with each other but less than 91% nucleotide sequence identity with all previously characterized begomoviruses, with the highest identity (90%) to an isolate of pedilanthus leaf curl virus (PeLCV). This indicates that the two hollyhock plants were infected with a newly identified begomovirus for which the name "hollyhock vein yellowing virus" (HoVYV) is proposed. HoVYV likely has a recombinant origin. The betasatellite showed the highest nucleotide sequence identity to an isolate of cotton leaf curl Multan betasatellite (CLCuMuB), a betasatellite associated with cotton leaf curl disease across Pakistan and northwestern India. These findings add to the diversity of known begomoviruses in South Asia and again highlight the role of hollyhock as a reservoir of the cotton leaf curl begomovirus betasatellite complex. The results also suggest that the yellow vein mosaic symptoms in hollyhock are due to the betasatellite rather than the virus.

Detection of Bean yellow mosaic potyvirus in infected faba bean plants (Vicia faba L.) from Northern Egypt

The Bean yellow mosaic potyvirus (BYMV) was isolated from naturally infected faba bean plants (Vicia faba L.) showing different symptoms of mosaic, mottle, and vein clearing, grown at certain locations of El Beheira governorate, Egypt, during the growing seasons from 2018- 2019. BYMV isolate was transmitted by Acyrthosiphon pisum, Aphis faba, A. nerii Boyer, Brevicoryne brassicae and Dactynotus sonchi L. in non-persistent manner. The virus was partially purified using polyethylene glycol PEG 6000, and differential centrifugation. The ratio of A 260/280 was 1.47. Whereas, the ratio of A max/min was 0.93. Concentration of the virus in the preparation was estimated using an extinction coefficient of E260 0.1% = 2.8 Yield of purified virus was about 14.8 mg/100g fresh weight of leaves of Vicia faba. Antiserum titer was determined by indirect enzyme linked immunosorbent assay (ELISA). Positive ELISA values were obtained up to dilutions of 1: 256000. The virus was detected by indirect ELISA in infected sap at 8 and 16 days after inoculation and by tissue blot immunoassay (TBIA) and dot blot immunoassay (DBIA) on nitrocellulose membrane after the same period. The unused face of the processed nitrocellulose membrane already printed with plant tissues revealed that both faces of nitrocellulose membrane and old processed nitrocellulose membrane could be used as solid carriers in TBIA, for detection of BYMV in infected leaves.

Complete genome sequence analysis of a novel coguvirus isolated from Paris polyphylla var. yunnanensis.

A novel negative-stranded (ns) RNA virus tentatively named "Yunnan paris negative-stranded virus" (YPNSV), was isolated from Paris polyphylla var. yunnanensis plants exhibiting leaf chlorosis and mosaic symptoms in Yunnan. Its complete genome sequence was determined using Illumina and Sanger sequencing. YPNSV has a bipartite genome that consists of a negative-stranded (ns) RNA1 encoding the viral RNA-dependent RNA polymerase (RdRp, p251), an ambisense RNA2 coding for the putative movement protein (MP, p46) and nucleocapsid protein (NP, p39), with the two open reading frames separated by a long intergenic region that is rich in A and U. Sequence comparisons showed that the RdRp, MP, and NP of YPNSV are most similar to those of watermelon crinkle leaf-associated virus 2 (WCLaV-2), with 69.1%, 50.4%, and 60.9% amino acid sequence identity, respectively. Phylogenetic analysis based on deduced amino acid sequences of RdRp and NP showed that YPNSV clustered in a clade with coguviruses and that its closest known relative is WCLaV-2. Based on the above results, YPNSV should be regarded as a new member of genus Coguvirus, family Phenuiviridae.

Weed-infecting viruses in a tropical agroecosystem present different threats to crops and evolutionary histories.

In the Caribbean Basin, malvaceous weeds commonly show striking golden/yellow mosaic symptoms. Leaf samples from Malachra sp. and Abutilon sp. plants with these symptoms were collected in Hispaniola from 2014 to 2020. PCR tests with degenerate primers revealed that all samples were infected with a bipartite begomovirus, and sequence analyses showed that Malachra sp. plants were infected with tobacco leaf curl Cuba virus (TbLCuCV), whereas the Abutilon sp. plants were infected with a new bipartite begomovirus, tentatively named Abutilon golden yellow mosaic virus (AbGYMV). Phylogenetic analyses showed that TbLCuCV and AbGYMV are distinct but closely related species, which are most closely related to bipartite begomoviruses infecting weeds in the Caribbean Basin. Infectious cloned DNA-A and DNA-B components were used to fulfilled Koch’s postulates for these diseases of Malachra sp. and Abutilon sp. In host range studies, TbLCuCV also induced severe symptoms in Nicotiana benthamiana, tobacco and common bean plants; whereas AbGYMV induced few or no symptoms in plants of these species. Pseudorecombinants generated with the infectious clones of these viruses were highly infectious and induced severe symptoms in N. benthamiana and Malachra sp., and both viruses coinfected Malachra sp., and possibly facilitating virus evolution via recombination and pseudorecombination. Together, our results suggest that TbLCuCV primarily infects Malachra sp. in the Caribbean Basin, and occasionally spills over to infect and cause disease in crops; whereas AbGYMV is well-adapted to an Abutilon sp. in the Dominican Republic and has not been reported infecting crops.

Natural mixed infections on Phalaenopsis species by groundnut bud necrosis orthotospovirus, cymbidium mosaic virus and odontoglossum ringspot virus in India

Three viruses belonging to different plant virus genera were found associated with Phalaenopsis plants showing symptoms of mild chlorotic spots, mild mosaic and dark green islands with light green depressions. Symptomatic and non-symptomatic plant samples were collected from the experimental farm of National Research Centre of Orchids, Pakyong Sikkim, India. Electron microscopy revealed the presence of virus particles with enveloped quasi-spherical, flexuous and rod-shaped particles morphologies measuring 80–110 nm, 480 × 13 nm and 300 × 18 nm respectively. In DAC-ELISA the symptomatic Phalaenopsis sample reacted with the antibodies raised previously to groundnut bud necrosis orthotospovirus (GBNV), cymbidium mosaic virus (CymMV) and odontoglossum ringspot virus (ORSV). Sequence information generated from the cloned RT-PCR amplified products, followed by sequence identity and phylogeny analyses, further confirmed the identity of the three different viruses as GBNV, CymMV and ORSV. Upon mechanical sap transmission on the N. benthamiana test plants, the phalaenopsis sample with mixed infection could induce a range of mixed symptoms such as systemic symptoms with blotching, mosaic, mottling and green-islands on the leaves, unlike those indicative of the symptoms known for the single infection by CymMV or GBNV or ORSV. The virus transmission and symptomatology revealed that the mixed infection by these three viruses masked the known symptoms of respective viruses induced individually. The present investigation describes the mixed infection by GBNV, CymMV and ORSV on Phalaenopsis for the first time in the world.

English

Cucumber (Cucumis sativus; family Cucurbitaceae) plants exhibiting begomovirus-like symptoms such as yellowing, mosaics and stunting were studied using cloning, sequencing, Species Demarcation Tool followed by phylogenetic clustering. The complete genome of DNA-A showed maximum sequence identity of 98.7% with the corresponding DNA-A of an isolate from “Iran” strain of Watermelon chlorotic stunt virus (WmCSV). The DNA-B displayed 97.5% nt identity with the component of DNA-B of WmCSV from Iran, too. Our results confirmed that yellowing and mosaic symptoms of cucumber are associated with a bipartite begomovirus (WmCSV). This study is the first characterization of WmCSV in association with described symptoms in cucumber from Oman. © 2021 Friends Science Publishers

Molecular characterization and infectivity analysis of tomato leaf curl New Delhi virus isolates infecting potato.

The online version contains supplementary material available at 10.1007/s13205-021-02752-5.

A new potyvirus isolated from Pennisetum alopecuroides with the potential to infect cereal crops

Pennisetum plants (Pennisetum alopecuroides L.), displaying a dwarfing phenotype along with delayed flowering and mosaic symptom on leaves, were found in Beijing, China. Flexuous filamentous particles with a size of approximate 15 × 850 nm were observed in symptomatic leaves via transmission electron microscopy. Deep sequencing of small RNAs (sRNA) from symptomatic leaves and analysis of sRNA populations were then conducted to determine the genome sequence of the viral agent in diseased plant tissues. It showed that the viral agent had one positive-sense and single-stranded RNA genome, which consisted of 9717 nucleotides (nts) excluding poly(A) tail. The complete viral genome contained a large open reading frame, encoding a polyprotein of 3131 amino acids (aa). Sequence comparison and phylogenetic analysis demonstrated that the viral agent belonged to the genus Potyvirus in the family Potyviridae. In the cladogram it was most closely related to johnsongrass mosaic virus, sharing 72% nt and 65% aa sequence identity. This viral agent was provisionally named pennisetum alopecuroides mosaic virus (PalMV). Subsequently, it was confirmed that PalMV is the causal agent of this new disease in P. alopecuroides by Koch’s postulates and reverse transcription-polymerase chain reaction analysis. Moreover, maize, millet, wheat, sorghum and rice plants were experimentally infected by PalMV via rub inoculation. Consequently, we proposed that PalMV could be a potentially dangerous virus threating a wide range of cereal crops.

Genetic Variability and Molecular Evolution of Maize Yellow Mosaic Virus Populations from Different Geographic Origins.

Maize yellow mosaic virus (MaYMV) hosted in various gramineous plants was assigned to the genus Polerovirus (family Luteoviridae) in 2018. However, little is known about its genetic diversity and population structure. In this study, 509 sugarcane leaf samples with mosaic symptoms were collected in 2017 to 2019 from eight sugarcane-growing provinces in China. Reverse-transcription PCR results revealed that four positive-sense RNA viruses were found to infect sugarcane, and the incidence of MaYMV among samples from Fujian, Sichuan, and Guangxi Provinces was 52.1, 9.8, and 2.5%, respectively. Based on 82 partial MaYMV sequences and 46 whole-genome sequences from different host plants, phylogenetic analysis revealed that MaYMV populations are very closely associated with their source geographical regions (China, Africa, and South America). Pairwise identity analysis showed significant variability in genome sequences among MaYMV isolates with genomic nucleotide identities of 91.1 to 99.9%. In addition to codon mutations, insertions or deletions also contributed to genetic variability in individual coding regions, especially in the readthrough protein (P3-P5 fusion protein). Low gene flow and significant genetic differentiation of MaYMV were observed among the three geographical populations, suggesting that environmental adaptation is an important evolutionary force that shapes the genetic structure of MaYMV. Genes in the MaYMV genome were subject to strong negative or purification selection during evolution, except for the movement protein (MP), which was under positive selection pressure. This finding suggests that the MP may play an important role in MaYMV evolution. Taken together, our findings provide basic information for the development of an integrated disease management strategy against MaYMV.

Efektivitas Pupuk Cair Pseudomonas fluorescens Agensia Pengendali Hayati Terhadap Penyakit Mosaik Tanaman Kakao

Cocoa is a strategic commodity for plantation in Indonesia. However, pest and disease infections are inevitably common constrains for the cocoa cultivators. Cocoa mosaic disease is one of disease which is cause cocoa trees suffering. Pseudomonas fluorescens are obligate aerobic bacteria that are very valuable for agricultural technology. The bacteria also protects plants from pathogens infection by producing secondary metabolites that kill bacteria and other fungi. The bacteria can used as safe and environmentally friendly biological control agents. This study aims to determine P. fluorescens liquid fertilizer formulation and its effectiveness in suppressing mosaic disease in cocoa plants. The research method was carried out by making a liquid formula from P. fluorescens and then applying it to cocoa plants that were attacked by mosaic disease. Bacterian isolates grown in conch broth medium were incubated for 3 days. Then the fertilizer formula was applied to mosaic symptomatic cocoa plants with fertilizer concentrations of 25%, 50% and 75% compared to spraying using chemical insecticides. The results showed that the liquid formula concentration of 75% can suppress the most effective mosaic symptoms and the optimal growth of cocoa plants for 7 treatments.

StPIP1, a PAMP-induced peptide in potato, elicits plant defenses and is associated with disease symptom severity in a compatible interaction with Potato virus Y.

The role of small secreted peptides in plant defense responses to viruses has seldom been investigated. Here, we report a role for potato (Solanum tuberosum) PIP1, a gene predicted to encode a member of the pathogen-associated molecular pattern (PAMP)-induced peptide (PIP) family, in the response of potato to Potato virus Y (PVY) infection. We show that exogenous application of synthetic StPIP1 to potato leaves and nodes increased the production of reactive oxygen species and the expression of plant defense-related genes, revealing that StPIP1 triggers early defense responses. In support of this hypothesis, transgenic potato plants that constitutively overexpress StPIP1 had higher levels of leaf callose deposition and, based on measurements of viral RNA titers, were less susceptible to infection by a compatible PVY strain. Interestingly, systemic infection of StPIP1-overexpressing lines with PVY resulted in clear rugose mosaic symptoms that were absent or very mild in infected non-transgenic plants. A transcriptomics analysis revealed that marker genes associated with both pattern-triggered immunity and effector-triggered immunity were induced in infected StPIP1 overexpressors but not in non-transgenic plants. Together, our results reveal a role for StPIP1 in eliciting plant defense responses and in regulating plant antiviral immunity.