American Phytopathological Society meeting

[ChrisK]

Hello from Austin! I'm attending this meeting and there is, of course, lots of tomato work. I'm happy to stop by posters and get more info if any of the abstracts jump out at you.

You can search the abstracts and let me know in the next day!

I found this one to be interesting and talked to the young researcher for quite a while. I pointed her to tomatoville as well.

[kurt]

This one caught my eye.Meeting | Practical application of UV-B radiation against powdery mildews under greenhouse conditions.

… suppression of powdery mildew in rose, cucumber, and strawberry following brief exposures to red li … plants with powdery mildew (Podosphaera aphanis) next to healthy plants. … for use against powdery mildews in commercial production of asters, cucumber, tomato, and several h …

[Worth1]

Enjoy Austin.

It is a wee bit on the warm side this time of year.

Worth

[ChrisK]

Kurt,

Pretty much all of the info on this poster was in the abstract.

In a nutshell, short exposure to UVB light at night dramatically reduced the disease severity of Podosphaera aphanis on the strawberry cultivar they chose. Exposure nightly was not better than every three nights.

The treatments they used were:
16 hrs of growlight (HPS lamps)
16 hrs of growlight + UVB
16 hrs of growlight + UVB + blower

Infection was from interspersed infected plants.

Best results were w/o the blower possibly due to increased spore dispersal with the blower. It did not look to me like the blower statistically changed the results though (I forgot to note if they were significantly different!)

The lights they used were:

HPS Lucalox LU400/XO/T/40
120 cm UVB tubes (UVB-313EL; Q-Panel Lab Products)

There was no mention of improved yield or fruit quality differences.

Hope that covered it.

[ChrisK]

Yah, tis hot...not as humid as Raleigh tho!

Originally Posted by Worth1

Enjoy Austin.

It is a wee bit on the warm side this time of year.

Worth

[Heritage]

Hi Chris,

If you get a chance it would be great if you could stop by this one:
http://www.apsnet.org/meetings/Docum...s2013abP24.htm

I am particularly curious to know the effectiveness of various seed treatments, either post-harvest, or pre-plant, to eradicate Cmm from systemically infected seed. Also, where in the seed has Cmm been observed (seed coat, endosperm, embryo...)

Thanks, have fun!

Steve

[amideutch]

Did a search on tomatoes and came up with some interesting topics.

http://www.apsnet.org/searchcenter/P....aspx?start1=1

Ami

[kurt]

Thank You, ChrisK.

[ChrisK]

Steve,

Re: this poster. It's an even numbered poster so the author will not be there today which is odd number poster day. (there are about 800 posters!) This is unfortunate because I had a lot of questions about it, incl some of the conclusions. I bet if you google the authors and contact them via email they will send you a copy of the poster, I can't post a copy for obvious reasons.

The objective was to determine routes of fruit and seed infection.

Briefly, the authors made a transgenic Clavibacter strain which expresses the Green Fluorescent Protein (GFP) and then infected the fruit topically by brushing it onto fruit at various stages or via injection into the stem-peduncle ★★★★★★★★ or pedicel. GFP is easy to visualize by using the right wavelength of light and looking for fluorescence. Can also be quantitative depending on application.

Fruit at various stages of development at injection were noted and subsequently sectioned and scored. The Clavibacter was easily visualized since it has the GFP expression while the plant tissue does not.

They had pretty pictures of infected tissues. They did not show sections of seeds to pinpoint infection, though. Looked like external seed coat.

here are their conclusions which I wanted to discuss with them.

• The pathogen can invade via both routes
• Active movement into fruit mesocarp and nearby xylem with external inoculation.
• Systemic and external inoculation can lead to seed infection (this is one question I had, from their table it had 1 fruit that showed this for both treatments)
• Seed can be infected w/o any plant or fruit symptoms
• Highest infection rate was 78% when injected and the fruit was at the dead flower/emerging fruit stage (another question: I couldn't find this stat anywhere on their poster except in the conclusions)

So, I don't think the poster really addressed your interest.


Here is an open access paper that was referenced on the poster which you might find interesting:

http://apsjournals.apsnet.org/doi/ab...DIS-02-11-0091

Abstract:

Clavibacter michiganensis subsp. michiganensis, causal agent of tomato bacterial canker, is a seedborne pathogen and is considered one of the most destructive bacterial diseases of this crop. For this reason, in the European Union and in many other countries, C. michiganensis subsp. michiganensis is a quarantine pathogen. It was first reported at the beginning of the twentieth century in Michigan (USA), and currently it is present worldwide. Its movement over long distances is facilitated by traded seeds, which explains its distribution throughout all of the tomato-growing regions of the world, but its spread differs widely among countries. However, it can also survive in plant debris and on volunteer plants or alternative hosts that can act as local sources of inoculum. Previous reviews regarding tomato bacterial canker were published in 1969 and 1993. This article discusses the current disease situation, integrating previous data with the most recent findings and new information available. The objectives of this article are: (i) to review the progress on tomato bacterial canker, the role of infected or infested seeds, and of local sources of inoculum in disease outbreaks; (ii) to provide an overview of plant health regulations; and (iii) to update information regarding research innovations and future perspectives on new, useful tools for detecting seed contamination that can aid in designing new strategies to improve control.


Let me know if you have other questions!

Chris

Originally Posted by Heritage

Hi Chris,

If you get a chance it would be great if you could stop by this one:
http://www.apsnet.org/meetings/Docum...s2013abP24.htm

I am particularly curious to know the effectiveness of various seed treatments, either post-harvest, or pre-plant, to eradicate Cmm from systemically infected seed. Also, where in the seed has Cmm been observed (seed coat, endosperm, embryo...)

Thanks, have fun!

Steve

[Tom Wagner]

Re: American Phytopathological Society meeting

Thanks Chris, I did a search for tomato for the 2013 abstracts and found lots of things I want to come back to for further study. I put in the quote button on subject matter that are in titles, paragraphs, key words, etc.

There is so much being submitted at this meeting that no one could possibly go up to the speaker on each one to ask further questions. My interests lie with variety disease resistance, seed-born pathogens, and low cost organic controls.

Since I am involved with many late blight breeding projects, I was especially interested in the Wapsipinicon Peach and Pruden's Purple...notably offering some hint of blight resistance. I knew that Matt's Wild had PH-2 and have used it in lots of crosses...now, I will access the former two for some crossing tests.

I do wish some of the presenters would post in TVille....a dialogue between those specialists and the members here would be great.

Below are some of the pertinent points that caught my eye and need a further lookie loo. I left my personal comments off since the list was so long.

Semi-dominant genes such as TY-1 and TY-2 confer resistance to TYLCV.

Seminis rootstock ‘Cheong gang’ had the least wilt incidence of 25% 75 days after transplanting (DAP). BHN 1054, RST-04-106, CRA66 and BHN998 rootstocks had slightly higher disease incidence of 33%, 35%, 43%, and 45% respectively. Susceptible non-grafted and self-grafted controls reached 100% disease incidence by 75 DAP.
study determined the efficacy of some OMRI approved products together with early blight (EB) resistant varieties, Mountain Fresh Plus F1 (MF+) and Juliet F1


first report of TASVd and PTSVd in Ghana and, similar to CLVd, they may have been introduced in association with tomato seed.
Development of switchgrass extractives as a biopesticide on tomatoes


CSI in a tomato disease plot: Engaging 4-H youth and educators in STEM through investigative plant pathology

Evaluation of the blight decision support system for the integrated management of potato and tomato late blight

we tested 11 tomato cultivars for resistance to 3 current clonal lineages, US-22, US-23, and US-24….. Pooling the lineages, 3 heirloom cultivars with no known resistance genes, Matt’s Wild Cherry, Wapsipinicon Peach, and Pruden’s Purple exhibited lesion lengths not significantly different (NSD) than Mountain Magic (contains Ph-2 and Ph-3 resistance genes).
study signifies successful antagonist nature of rhizosphere fungal consortium which has shown potential to reduce the use of chemical pesticides
The homozygous Ph2 and Ph3 genotype of these hybrids fully controlled LB; plants had no symptoms in fields where susceptible cultivars were severely defoliated. The homozygous EB tolerance does not provide complete control


Torradovirus and two tospoviruses begomovirus curtovirus papita viroid. Bunyaviridae “caulimo-like” virus
nepoviruses
Nepoviruses infecting imported plant germplasm


An useful antagonistic strain of Aspergillus for control of root knot nematode.

Bacterial communities in the soils may have played a role in reducing southern blight on tomato


Investigate strategic ‘stacking’ of these biocontrol agents (thymol) Thymol is a constituent of oil of thyme, a naturally occurring mixture


cool virulent strain of Bacterial Wilt can reveal virulence factors at low temperatures.

Strain A316 from the South Pole produced a phenol-like compound that killed the root-knot nematode. It also increased the activity of induced resistance enzymes such as peroxidase (POD) and polyphenoase (PPO) in tomato, and enhanced the resistance of tomato against the root-knot nematode.


Physiological benefits of seed treatments.

Antibacterial activity of mycelial extracts from submerged cultures of shiitake on tomatoes

Late blight severity of 26-100% resulted on potato, tomato, and weed foliage of plants lacking Ph-2/Ph-3 or RB genes. Plants with Ph or RB genes were resistant.


bioagent, Trichoderma, a naturally occuring fungus in agricultural and forest soils, is used by biological control programs in seed treatments, in foliar sprays, in compost,


Bacillus sp. F727 controls a spectrum of plant pathogens in vitro and consistently controls Botrytis cinerea on tomato


cover crops could rapidly enhance microbial communities suppressive to pathogen growth


Some of the fungal pathogens detected from Saharan dust storms are Humicola fuscoatra (tomato plant root pathogen)


stomatal pores in the leaf epidermis close as a part of the plant innate immune response against bacterial invasion of plant tissues.


Evolutionary genetics factors underlying the emergence and spread of plant RNA viruses.

Evaluation of seed wash DNA extraction method for the detection of seed-borne plant pathogens.

Soil microbes in organic vs. conventional vegetable production: Capturing the active players

A small portion (3%) of seedlings germinated from botanical potato seed accession JCM-23 imported from South America showed severe upper leaves deformation and necrosis.


A whole plant disease resistance assay was performed on 7-week-old seedlings by inoculating with a mixture of the P. infestans clonal lineages of US-22, -23 and -24. 8 plants progenies were selected as resistant and crossed with the tetraploid S. tuberosum cultivars MegaChip and White Pearl, and diploid hybrids HC (an interspecific hybrid) and XD3 (a hybrid between US-W4 and S. chacoense). Seed were formed only in fruits from crosses to XD3. 174 progeny were screened for resistance to late blight. Twelve plants were selected as resistant.


We have previously demonstrated suppression of powdery mildew in rose, cucumber, and strawberry following brief exposures to red light and UV-B radiation during night hours.

I am hoping when folks search for any key word(s) that it will link to this topic post here at TVille in addition to the abstracts. Most will never access or pay for the whole article but maybe a few of us could make this information more easily obtained by goading the original authors to chime in. Only saying!

[Heritage]

Chris, thanks much for the info on the poster and link to the article, it's been very helpful!

Since I receive seeds from all over the world I am especially paranoid about Cmm and TMV transmitted via seed. The conclusion "Seed can be infected w/o any plant or fruit symptoms" is of particular concern, and only adds to my paranoia. I use Immunostrips to monitor for both, and so far have been lucky, but it is very helpful to understand the mode of transmission and effective method of eradication from seed, so, if I ever do get a positive test, I will be able to eliminate the disease from both the field and seed.

Thanks again for your time!
Steve

[ChrisK]

I do hope she comes here! She had an interesting story about Wap. Peach (I hope I get this right, i'm in information overload at the moment). Apparently the breeder of that variety had done some other crosses with pimpinell. Could be where this resistance came from, but the parentage was unclear for Wap. peach. It was intriguing that when this was bred LB was not an issue and certainly the newer isolates were not around. It would be very unlikely that he selected for this trait. Are there other genes than PH2 and 3 that give resistance to LB in this line?

I'll stop by that poster again

Yes, there is an overwhelming amount of info being presented.

See: E. S. CARMAN: One of the Greatest of American Plant Breeders—His Work Too Little Appreciated—Success With Potatoes Most Noteworthy—His Activity as a Journalist J Hered (1915) 6 (2): 65-67 (unfortunately, not open access)

Originally Posted by Tom Wagner

Snip!

[ChrisK]

Meeting has wrapped up. I thoroughly enjoyed it and learned a lot (incl. some work related stuff!) There is a tremendous amount of innovation driven by fantastic science going on in agriculture. The speed in which things have changed in the last 15 years astonishes me and it's an amazing time to be involved in it!