Alternative hosts for Spongospora subterranea under semi-arid conditions Leah Tsror Dep. of Plant Pathology, Agricultural Research Organization, Gilat Research Center, Israel [email protected] Powdery scab Workshop, 2016, Switzerland
Alternative hosts for Spongospora subterraneaunder semi-arid conditions
Leah Tsror
Dep. of Plant Pathology, Agricultural Research Organization, Gilat Research Center, Israel
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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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
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