Alternative hosts for Spongospora subterraneaunder semi-arid conditions

Leah Tsror

Dep. of Plant Pathology, Agricultural Research Organization, Gilat Research Center, Israel

tsror@agri.gov.il

Powdery scab Workshop, 2016, Switzerland

Potato Production in Israel

Spring Autumn/Winter

Planting date Dec-Feb Sep-Nov

Irrigation 5,500 m3/ha 3,800 m3/ha

Seed potatoes 25,000 t Import 35,000 t Local

Average yield 55 t/ha 40 t/ha

Area 7,400 ha 7,700 ha

Imported seed

Less than 200 mm annual rainfall

44%

50%

6%

Export Local market processing

59%

33%

8%

EU UK Estern Europe

Exporting to Europe

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Evap

Tem

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Month

Evap T.max T.min

Negev Climatic Conditions

Western Negev

Annual rain fall (November-March) - 30-300 mmaverage max temperature 30°C;

average evaporation 5-8 mm/day

Poor soils (loess, sandy) - <0.6% organic matter

Powdery scab and root gall symptoms

Israeli phyto-sanitaric requirements (partial)

• Brown & ring rot: zero tolerance (field inspection)• PVYNTN: zero tolerance (tuber inspection)• Dickeya zero tolerance (tuber inspection)

• Blackleg: <0.5% infected plants in the field

• Common scab: 66% of the tubers <1/6 of surface; 1% -more 5 spots; 0.3% deep scab

• Powdery scab: 1% of the tubers <1/8 of surface;zero tolerance to cankerous form

• Black scurf: 10% of tubers (1/8 of tuber surface);1% higher than 1/8

• Black dot: 30% of tubers (1/3 of tuber surface);

• Late blight: 0.3% of tubers• Fusarium&Phoma: 1% of tubers

Import regulations

Monitoring seed lotsSample of 200 tubers/lot

Silver scurfBlack dot

Black scurf Powdery scab

Seed borne inoculum

Reported host range of Spongospora subterranea

Naturally-infected plants: Nightshade weeds (Solanum physalifolium, S. sarrachoide)Nitzan et al. 2009. Am. J. Pot. Res.Shah et al. 2010. Aust. Plant Pathol.

Artificially-inoculated plants: Tomato, Oat, Rapeseed, Buckwheat, Radish, Red clover, Rye; S. ptycanthus, Brassica, Dactylis, Datura; Chnopodium, Cyperus, Ambrosia, Amarnthus, PhleumQu & Christ. 2006. Am. J. Pot. Res.

Tomato, Celery, Carrot, Corn, Cabbage, Parsley, Bean, Cucumber, Onion, Pea, Maize;Datura,S. nigrum, S. quitese, SonchusAristizibal et al. 2013. Rev.Fac.Nal.Agr.Medellín

Characterizing the host range of Spongospora in Israel

Objectives

Hypothesis:

• Weeds and rotational crops may serve as alternative hosts

• Complete life cycle doesn’t occur in all potential hosts (trap plants)

Specific objectives:

• To determine the ability of Spongospora to infect and complete life

cycle in rotational crops

• To determine its ability to infect weeds prevalent in potato fields

Levels of work and methodology

Spontaneous/natural infections

Sampling of plants in infested plots located in the Negev (based on history of crops and soil testing)

weeds (217 plants)rotational crops (38 plants)potato volunteers (13 plants)

Shikma, plot 185; high soil-inoculum

Levels of work and methodology

Artificial inoculation

Weeds

typical to the region of potato production

in Negev ; seeds were obtained from the

Israeli Gene Bank, Faculty of Agriculture &

weed research lab@ARO

Crops rotated with potato

Wheat (3 cvs), barley (2 cvs), oat (2 cvs),

peanut, carrot, radish, onion, lucerne,

Inoculation of seedlings with sporosori

[in Hogland solution or in pots

(soil+peat+vermiculite)] - first 2 weeks at 15C,

then 21C. Testing at 14, 30, 90 dai.

Levels of work and methodology

Plant roots were surface sterilized and cut for:1: staining & microscopic observation2: freeze dried, ground in liquid nitrogen, stored -20CTotal DNA of each root (0.03gr dried tissue) was extracted using MasterPureTM Yeast DNA Purification Kit, RT-PCR analysis (van de Graaf et al. 2003)

Natural infections of weeds and rotational crops

Out of 49 species (from 18 families) 18 are positive in RT-PCR testing; Microscopic testing is on-going

Medicago radiataAstragalus hauraensis

Matthiola longipetala Brassica tournefortii

Phalaris minor

Family Scientific name % infec.

Amaranthaceae Amaranthus albus 57% (4/7)

Asteraceae Verbesina encelioides 67% (2/3)

Brassicaceae Diplotaxis erucoides 100% (5/5)

Brassicaceae Brassica tournefortii 67% (6/9)

Brassicaceae Matthiola longipetala 67% (2/3)

Chenopodiaceae Chenopodium murale 93% (14/15)

Chenopodiaceae Chenopodium opulifolium 100% (5/5)

Chenopodiaceae Salsola soda 100% (1/1)

Fabaceae Medicago radiata 100% (1/1)

Fabaceae Astragalus hauraensis 50% (1/2)

Malvaceae Malvella sherardiana 17% (1/6)

Poaceae Rostaria cristata 100% (1/1)

Poaceae Phalaris minor 25% (1/4)

Poaceae Cynodon dactylon 29% (2/7)

Ranunculaceae Adonis dentata 50% (1/2)

Solanaceae Solanum elaeagnifolium 50% (1/2)

Solanaceae Solanum nigrum 88% (7/8)

Zygophyllaceae Tribulus terrestris 100% (1/1)

Poaceae Triticum aestivum 40% (12/30)

Poaceae Hordeum vulgare 25% (2/8)

Solanaceae Solanum tuberosum 77% (10/13)

Solanum nigrum Solanum elaeagnifolium

Artificial inoculation of weeds and rotational crops

Family Scientific namePoaceae Setaria verticillata 33% (2/6)

Poaceae Phalaris paradoxa 22% (2/9)

Poaceae Phalaris minor 43% (3/7)

Brassicaceae Sinapis arvensis 33% (1/3)

Brassicaceae Diplotaxis erucoides 17% (1/6)

Solanaceae Solanum nigrum 8% (1/12)

Poaceae Triticum (C9) 43% (3/7)

Poaceae Triticum (Galilee)

43% (3/7)

Solanaceae Solanum lycopersicum 56% (5/9)

Brassicaceae Raphanus sativus var radicula 33% (2/6)

Poaceae Avena sativa (Paeya 4) 36% (5/14)

Poaceae Hordeum vulgare (Noga) 33% (2/6)

Solanaceae Solanum tuberosum 100% (4/4)

Rotational crops: out of 10 species (from 6 families) 6 were positive in RT-PCR testing: wheat, radish, oat, barley, tomato, potatoWeeds: out of 14 species (from 7 families) 6 were positive.Microscopic testing is on-going

RadishX400

Updated host range of Spongospora subterranea

Naturally-infected plants: Nightshade weeds (Solanum physalifolium, S. sarrachoide)WheatBarleyS. nigrum, S. elaeagnifolium, Medicago radiate, Verbesina, Diplotaxis, Matthiola, Salsola, and more

Artificially-inoculated plants: Tomato, Oat, Rapeseed, Buckwheat, Radish, Red clover, Rye; S. ptycanthus, Brassica, Dactylis, Datura; Chenopodium, Cyperus, Ambrosia, Amarnthus, PhleumTomato, Celery, Carrot, Corn, Cabbage, Parsley, Bean, Cucumber, Onion, Pea, Maize;Datura,S. nigrum, S. quitese, SonchusWheat, BarleySetaria, Phalaris, Sinapis, Diplotaxis

Thanks

Rotem Shapira, Orly Erlich, Kristina Tavrizov, Marina Hazanovsky and Sara Lebiush

funded by Chief Scientist of Agricultural Ministry