Overview of blueberry diseases annemiek schilder dept. Diversity, host range, and the impact of farming practices on disease incidence abstract the coconut palm cocos nucifera is a major cash crop that is widely grown in coastal tropical regions of the. We are constructing a largeinsert library to connect repeatrich regions flanking the 9 contigs. Plant diseases caused by phytoplasma and spiroplasma by. The primary visible effect are yellowing leaves, stunted and rolled foliage and unripened shoots and fruits. The less the phytoplasma multiplies winetwork is a worldwide. Detection of phytoplasmas in watercress and onion plants. The latest research on grapevine viruses and phytoplasmas. Salicylic acid studies have revealed that several salicylate biosynthetic genes are upregulated in the midribs or whole leaves of grapevine infected with the phytoplasma ca. Coconut lethal yellowing phytoplasma disease in mozambique. Among the crops, affected are peppers, eggplant, potato, celery, carrots, strawberries, grapes, tobacco, lavender, and avocado.
Ppt is caused by phytoplasma and is transmitted by insects in the cicadellidae family. Effects of phytoplasma infection on salicylic acid biosynthesis and signaling. A new disease with symptoms similar to ppt was recently observed in texas and nebraska, usa. In the second system, phytoplasmas are classified into candidatus phytoplasma species, based on the nucleotide sequence of the 16s rrna gene. The phytoplasmas are found in the phloem cells of host plants, and are normally considered pathogens of plants. Phytoplasma presence in cassava showing frog skin cfsd and witches broom cwb. The black wood of grapevine disease is classified as part of the grapevine yellows. Sequencing the 16s rrna of the oenothera phytoplasma revealed that plantpathogenic phytoplasmas are distinct from animal mycoplasmas lim and sears, 1989. Exploring the phytoplasmas, plant pathogenic bacteria, journal of general plant pathology, 2014, pp. Nicolaisen 26 fruit tree phytoplasma diseases and vectors in belgium, netherlands, and united kingdom g. Integrated management of phytoplasma epidemics in different crop systems new perspectives in phytoplasma disease management book of abstracts of presentations work groups 23 22 march 20, barcelona, spain organized by alplanta institute for plant research, neustadt. Sequence analyses of the 16srdna allow producing a detailed picture of phytoplasma diversity and of their.
The diagram to the right illustrates the three factors required for disease development. The phytoplasmas cannot be cultured on artificial media, and can only be maintained in their plant host. They multiply in these plants which are sometimes a source of inoculum. In this presentation, preliminary results on the selection of suitable marker. Symptoms and spreading of phytoplasma diseases a common symptom resulting from phytoplasma infection is phyllody, a condition in which a plant produces leaf like structures instead of flowers. Impact cassava is the third most important crop in the tropics after rice. In severe infections, this pathogen can cause yield losses of nearly 100%.
In this system, the nucleotide sequences of 16s rrna genes from different phytoplasmas are aligned by a sequence alignment computer program, and the % identities among the sequences are calculated. Methods of spread are unknown for any of them, except for movement in stem cuttings used for planting. Potato purple top wilt ppt is a devastating disease that occurs in various. Ppt phytoplasma was readily differentiated from closely related phytoplasmas candidatus phytoplasma japonicum, candidatus phytoplasma caricae, candidatus phytoplasma graminis, candidatus phytoplasma australiense and stolbur phytoplasma fig. Please retain photo credits on pictures used from this site. Pinp pine phytoplasma, ppt potato purple top wilt, ppwb caribbean pigeon pea witches broom, rhy rhus yellows, ryd rice. Three of these genomes contain large amounts of repeated dna sequence, and the fourth carries multiple copies of almost 100 genes. Numerous outbreaks of lyds of coconut have been recorded in the caribbean and africa since the late nineteenth century and have caused the death of millions of palms across several continents during the twentieth century. The recent discovery of bogia coconut syndrome in papua new guinea png is the first report of a lethal yellowing disease lyd in oceania. Pictured abouve is a close up view of characteristic patchy red symptoms associated with phytoplasma infection in a red table grape variety in turkey.
Molecular diversity of phytoplasmas is also demonstrated by studying genes coding the ribosomal proteins s3, tuf, secy, amp, imp and other genes. Despite their economic importance, phytoplasmas remain. Phytoplasma from the potato stolbur group infect over 45 species in the solanaceae, and at least 16 species belonging to six other botanical families. Evidence suggests that in stolburinfected tomatoes, the phytoplasma deregulates a gene involved in flower formation pracros et al.
Metabolic discrimination of catharanthus roseus leaves. Based on this pra, candidatus phytoplasma phoenicium was added to the a1 lists of pests recommended. Four phytoplasma genomes have been fully sequenced, including those of two candidatus phytoplasma asteris strains, and those of strains of ca. Exploring the phytoplasmas, plant pathogenic bacteria. An introduction and classification with recent molecular. Phytoplasmas and phytoplasma diseases semantic scholar. The phytoplasma genome is atrich and contains many repeats. The timing for sampling plant tissues is important as location in the. Two oligonucleotide primers were designed from the 16s rrna of oenothera phytoplasma, and were shown to be fully homologous with corresponding sequences of all other phytoplasmas, including. This phytoplasma aurantifolia group has been recorded from weeds. Phytoplasma titre can be affected by phytoplasma strain or species, host plant species, timing of infection and climatic conditions.
Molecular detection and classification of the phytoplasma. Potato introduction potato purple top ppt disease has been reported worldwide. Translocation of phytoplasma in plants phytoplasmas enter in to sieve tubes through insect transmission and moves throughout the plant body via phloem along with the cell sap they are very poorly distributed in the. Our results revealed that, following exogenous ga application and subsequent ppt phytoplasma graft inoculation, there was an apparently coordinated down. Columbia basin potato purple top ppt phytoplasma is a candidatus phytoplasma trifoliirelated strain responsible for ppt disease epidemics that have repeatedly occurred in the pacific northwest region of the united states during the past decade. Plant diseases caused by phytoplasma and spiroplasma 1. The objective of this research was to identify and classify at a molecular level the causal agents of ppt. Bianco chapter 1 the phytoplasmas and phytoplasma vectors in cost fa0807 countries introduction content 7 phytoplasmas and cost action fa0807 a. Restriction fragment length polymorphism rflp and sequence analysis indicated that ppt phytoplasma belongs to the 16sri group and phs phytoplasma fits in the 16srii group. Managing these factors can also help prevent and suppress disease populations. Certificate of original work this is to certify that this thesis entitled detection, identification and molecular characterization of phytoplasma diseases in uttar pradesh region of india submitted for the award of the degree of doctor of philosophy in biotechnology, embodies a bonafide research work carried out by ms. Candidatus phytoplasma solani, the causal agent of the black wood of grapevine, is a bacterial phytoplasma species of the 16srxii group. Phytoplasma effector sap54 hijacks plant reproduction by.
Canadian journal of microbiology canadian science publishing. These symptoms can be confused with grbav infection. Exploring the phytoplasmas, plant pathogenic bacteria pdf. The phytoplasma belongs to a lineage previously termed as beet leafhoppertransmitted virescence agent, which has a broad plant host. The phytoplasmas are very small prokaryotes which are related to bacteria, but in contrast to bacteria they do not have a cellwall. The introduction of diagnostic tests based on 27 quantitative pcr assays qpcr showed to be highly sensitive, and reduced the risk of amplicon contamination. Phytoplasma are reliant upon their insect vectors for dispersal in the environment, and the association between the phytoplasma and the insects can be beneficial to both organisms. Detection and molecular characterization of a 16srif.
The genbankemblddbj accession numbers for the 16s rrna gene sequences of montana potato purple top phytoplasma ppt mt1171, pecan bunch phytoplasma pb1, goldenrod yellows phytoplasma gr1 and alaska potato purple top phytoplasma ppt ak6 determined in this study are fj226074, fj376626, fj376627 and fj376629. Outlook about persepectives and future work to contain spread of these diseases are also reported. Current status and perspectives of phytoplasma disease research. The first comprehensive phytoplasma classification scheme was based on rflp analysis of pcramplified 16s rdna, providing a reliable means for the differentiation of a broad array of phytoplasmas and has become the most comprehensive and. Role of gibberellic acid in tomato defence against potato. Phytoplasma diseases on potato appear to increase in importance worldwide. Definition phytoplasmas are obligate bacterial parasites of plant phloem tissue and of the insect vectors that are involved in their planttoplant transmission. Plant diseases caused by phytoplasma and spiroplasma. Potato purple top wilt ppt is a devastating disease that occurs in various regions of north america and mexico. Plant, soil, and microbial sciences michigan state university. Phytoplasma definition of phytoplasma by merriamwebster. Genome sequencing of phytoplasmas, pathogens of insects. In this paper, we report that the two different phytoplasmas have been found coexisting in the same potato plant, which demonstrates the presence of mixed infection in the.
The entire genome sequence has been completed for two strains of aster yellows candidatus phytoplasma asteris, two strains of ca. An emerging problem in the pacific northwest usa is a purpletop disease caused by a clover proliferation group phytoplasma vectored primarily, but not exclusively, by beet leafhopper. Bacteria that manipulate plants and insects article pdf available in molecular plant pathology 94. Keywords phytoplasma diseases, detection, prevention 1. Phytoalexins are defined as low molecular weight, anti microbial compounds that are both synthesized and accumulated in plants after exposure to microorganisms or abiotic agents the term phytoalexin is derived from greek. The phytoplasmas and phytoplasma vectors in cost fa0807 international countries 23 phytoplasmas and phytoplasma vectors in denmark, finland, lithuania and norway m. Phytoplasmal infection derails genetically preprogrammed. At least three distinct phytoplasma strains belonging to three different phytoplasma groups 16sri, 16srii and 16srvi have been associated with this disease. In contrast, phytoplasma are aggressive pathogens of plants, and exposure of a susceptible plant to phytoplasma eventually leads to the death of the plant. Several economically relevant phytoplasmaassociated diseasesare described together with an update of phytoplasma taxonomy and major biological and molecular features of phytoplasmas. Phytoplasma definition is any of a group of bacteria that are related to mycoplasmas, cause plant diseases such as aster yellows or elm yellows by infecting phloem tissue, and are transmitted especially by homopteran insect vectors called also mycoplasmalike organism. Phytoplasmas are insecttransmitted plant pathogenic prokaryotes causing serious.
33 31 1096 1007 1479 414 983 513 1088 864 148 99 703 1277 1334 661 1151 575 214 1428 384 1496 1357 1530 623 920 1438 1462 137 461 468 1278 1348 268 303 190