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ACCESSION NO: 0411762 SUBFILE: CRIS

PROJ NO: 3607-21000-015-13S AGENCY: ARS 3607

PROJ TYPE: USDA COOPERATIVE AGREEMENT PROJ STATUS: NEW

START: 24 SEP 2006 TERM: 23 SEP 2011

INVESTIGATOR: KRAUSE C R; LEISNER S

PERFORMING INSTITUTION:

UNIVERSITY OF TOLEDO, THE

2801 W BANCROFT ST

TOLEDO, OHIO 43606-3390

ENHANCING GREENHOUSE SOILLESS CULTURE PRODUCTION WITH IMPROVED DISEASE

AND PEST MANAGEMENT

OBJECTIVES: Silicon amendments will be studied to alleviate copper toxicity and delay viral

symptoms. Interactions of Pelargonium flower break virus, a common virus infecting geraniums will

be examined with its plant host. The purpose of this research is to assist plants to better deal with

copper toxicity and virus pathogens. These changes reflect those made in the Parent project plan

approved in 2008.

APPROACH: The gene implicated in antiviral defense was identified by Dr. Leisner from

Pelargonium species. Interactions among the proteins of Pelargonium flower break virus, the most

common and highly contagious viral pathogen of Pelargoniums (geraniums) will be studied using

molecular techniques. PFBV protein interactions initially will be examined by yeast two- hybrid

analysis. Protein interactions will be confirmed by pull- down assays using maltose-binding protein

and glutathione-S- transferase fusion proteins. The domains participating in the protein interactions

will be identified by generating deleted forms of the PFBV proteins and analyzing interactions by

yeast two-hybrid analysis. Electron microscopy will be used to characterize the pathogen and

determine its effects on various tissues. Molecular techniques and electron microscopy will be used

to study interactions between silicon on a geranium virus and copper toxicity in greenhouse and

growth chambers.

PROGRESS: 2010/10 TO 2011/09

Progress Report Objectives (from AD-416) Silicon amendments will be studied to alleviate copper

toxicity and delay viral symptoms. Interactions of Pelargonium flower break virus, a common virus

infecting geraniums will be examined with its plant host. The purpose of this research is to assist

plants to better deal with copper toxicity and virus pathogens. These changes reflect those made in

the Parent project plan approved in 2008. Approach (from AD-416) The gene implicated in antiviral

defense was identified by Dr. Leisner from Pelargonium species. Interactions among the proteins of

Pelargonium flower break virus, the most common and highly contagious viral pathogen of

Pelargoniums (geraniums) will be studied using molecular techniques. PFBV protein interactions

initially will be examined by yeast two- hybrid analysis. Protein interactions will be confirmed by

pull- down assays using maltose-binding protein and glutathione-S- transferase fusion proteins.

The domains participating in the protein interactions will be identified by generating deleted forms

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of the PFBV proteins and analyzing interactions by yeast two-hybrid analysis. Electron microscopy

will be used to characterize the pathogen and determine its effects on various tissues. Molecular

techniques and electron microscopy will be used to study interactions between silicon on a

geranium virus and copper toxicity in greenhouse and growth chambers. This is a congressionally

mandated SCA. Over the lifetime of this project Argonaut genes (AGO) were studied to determine

regulation of flower development and virus resistance. AGO were studied in 23 accessions from the

Ornamental Plant Germplasm Center (OPGC) (Ohio State University, Columbus, OH) and were

found to be infected with Artichoke Italian Latent Virus (AILV). Also detected was the Pelargonium

pattern line virus (PLPV) through sequencing. Silicon (Si) alleviated copper (Cu) toxicity symptoms

in Arabidopsis plants and Zinnia. Si is also playing an intracellular role rather than being limited to

holding Cu in the cell wall. Si can delay Tobacco ringspot virus (TRSV) systemic symptoms in

tobacco. While all three domains for the PFBV and PLPV CPs are able to bind to the full-length

protein, only the end of the DNA or RNA play a role in cross-association. Pelargonium flower break

virus was the most common virus detected and may exhibit symptoms, chlorotic rings, or no

symptoms at all. A large majority of the pelargonium cultivars were infected from the OPGC

collection but many did not exhibit symptoms. Studies were extended to snapdragon and zinnia,

which are at the opposite extremes of the Si-accumulation spectrum: low and high accumulators,

respectively. Biological effects of extra Si to hydroponic solutions delayed systemic symptom

formation by Tobacco ringspot virus (TRSV) in N. tabacum. This data indicates a correlation

between the delay of TRSV infection and higher levels of Si uptake in leaves, suggesting that leaf

Si uptake is regulated in N. tabacum. Research indicated that Si could alleviate Cu toxicity stress,

but the degree of stress alleviation correlated with the amount of Si the plants acquired. This

research relates to the ARS parent project, Objective 1; Subobjective 1b: Determine uptake,

accumulation and potential benefit of silicon in ornamental crops and for its use as a buffer to Cu

toxicity and as an alternative to pathogen control. The project has been monitored by written

reports, meetings and phone calls.

PUBLICATIONS (not previously reported): 2010/10 TO 2011/09

No publications reported this period.

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