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STRATEGIES OF REPRODUCTION AND OF VIABILITY SUPPORT OF OOMYCETE PHYTOPHTHORAINFESTANS IN IRAN
Zolfaghary A. - Ph.D., student of Department of Plant Protection, RTSAU; e-mail: amir.zolfaghary@gmail.com
Smirnov A.N. - Dr. Sc., Professor of Department of Plant Protection, RTSAU;
e-mail: smirnov@timacad.ru
Abstract: the paper describes living and infective cycles Phytophthora infestans (Mont.) de Bary in Iran Province Golestan. 3 255 blighted samples from potato and tomato leaflets were collected in 2009-2011 from private commercial fields (0.5-4 hectares) of seven locations. These samples represented 123 and 30 field P. infestans populations from potato and tomato respectively. The maximum means of disease frequency, disease severity, indexes of presence of zoosporangia and aggressiveness were registered for P. infestans field populations from potato and tomato not treated with fungicides. Especially aggressive were tomato populations from not local for Iran tomato cultivar Early Girl. On the contrary, low-leveled aforementioned features were obtained for potato populations of different origin treated with fungicides Equation pro and Ridomil Gold. All investigated P infestans field populations were asexual with different levels offormation of zoosporangia. Weak and asexual strategies of reproduction were revealed. No oospores were revealed. This investigation has clearly demonstrated that in spite of current climate warming P. infestans still can be very dangerous pathogen which must be carefully monitored both in Iran and in Russia.
Key words: Phytophthora infestans, potato late blight, tomato late blight, Iran, Golestan, zoosporangia, strategies of reproduction, strategies of viability support.
Phytophthora infestans (Mont.) de Bary is still very dangerous potato and tomato pathogen in spite of trend to climate warming [6]. This organism is well investigated in almost all regions of the world, but Iran is still an exception. Little is known about potato and tomato late blight in Iran. For example, influence of climatic conditions on late blight development was investigated [5, 7, 8].
Nothing is still known about specifics of living and infective cycles of P infestans in Iran. It is rather ridiculous because potato affection in Iran can be very essential with strong lost of harvest, for example in Ardebil (1997), Golestan (2002, 2o06) [5, 1]. Aim of the present investigation is providing true information about P. infestans living and infective cycles in Iran. For Iran, the obtained data are new and of urgent importance. For Russia, these data also can be very useful because of intensification of trade and economic interrelations between Russia and Iran. Thus, it is important to elucidate possible danger of Iran P. infestans populations for Southern regions of potato and tomato cropping in Russia, to estimate their potential of reproduction and viability under the field conditions.
Material and methods
In 2009-2011, 3 255 blighted samples from potato and tomato leaflets were collected from private commercial fields (0.5-4 hectares) of seven locations in Iran Province Golestan. These samples represented 123 and 30 field P infestans populations from potato and tomato respectively (fig. 1, 2, table 1). Different potato and tomato cultivars were used
Fig. 1. Map of Iran. Province Golestan is yellow-marked
Fig. 2. Golestan province: abbreviation in map: Az Azadshahr BT Bandar-e Torkaman K Kalaleh Go Gonbad Kavoos Ko Kordkooy Ga GaJjkeshM Minoodasht R Ramiyan BG Bandar-e Gaz Ag Agh Gha Y Yassaghi- K Kafshgiri- G Gorgan- S Sorkhan Kalate- V Valikabad- F Fazelabad- A Aliabad-e Katul Y Yassaghi: 36° 49' 32" N, 54° 14' 28" E
Geographic coordinates and altitude of investigated locations
Region Geographic coordinates (GPS) Altitude (m)
North East
Y Yassaghi 36° 49' 32" 54° 14' 28" 65
K Kafshgiri 36° 48' 36" 54° 17' 02" 85
G Gorgan 36° 50' 19" 54° 26' 5" 155
S Sorkhan Kalate 36° 52' 2" 54° 29' 7" 105
V Valikabad 36° 53' 29" 54° 34' 9" 51
F Fazelabad 36° 53' 54" 54° 44' 59" 186
A Aliabad-e Katul 36° 54' 30" 54° 52' 8" 140
in this investigation. Part of them were regularly treated with fungicides during vegetation season, other part of them was not treated. During field observation disease frequency (DF - per cent of blighted plants), disease severity (DS - per cent of necrotized leaf cover) were estimated).
After incubation in moist chambers (1 day), boiling ethanol (5 min) and 10% bleaching chlorine (2 hours), decolorized leaflets were checked for determination of P infestans zoosporangia and oospores. Index of presence of zoosporangia (IZ) and oospores (IO) were calculated. Index of aggressiveness (IA) of field P. infestans populations was calculated as IA=(DFDSIZ)/10000 [2, 3].
Distribution of indexes IZ and IO for asexual P infestans populations gave an outline for two strategies of reproduction (SR): W (weak) with substrategy W1 (IZ=0.1-20.0), A (asexual): with substrategies A1 (IZ=20.1-40.0), A4 (IZ=40.1-60.0), A7 (IZ= =60.1-100.0) [2, 3].
Maximum means of features DF, DS, IZ, IO, IA were 100%, minimum means were 0%.
Distribution of indexes IA and IO for asexual P infestans populations gave an outline for two strategies of viability support (SVS): W (weak) with substrategy W1 (IA=0.1-10.0), A (aggressive): with substrategies A1 (IA=10.1-25.0), A4 (IA=25.1-50.0), A7 (IA= =50.1-100.0) [2, 3].
LSD05 was determined by means of software STRAZ. P infestans potato field population from Valikabad of2009 was used as a control. Correlation analysis was performed by means of Microsoft EXCEL (2007), cluster analysis - by means of STATISCA 7.0.
Results and discussion
All field P. infestans populations manifested rather significant means of disease frequency, disease severity, index of presence of zoosporangia, index of aggressiveness (table 2). No oospores were detected.
The maximum features were registered for populations from potato and tomato not treated with fungicides. Especially aggressive were tomato populations from not local for Iran tomato cultivar Early Girl. On the contrary, low-leveled features were obtained for potato populations of different origin treated with fungicides Equation pro and Ridomil Gold (table 2).
Disease frequency (DF), disease severity (DS), index of formation of zoosporangia (IZ), index of aggressiveness (IA) for groups of potato and tomato field P. infestans populations
Groups of P. infestans field populations Features, %
Year, Number
host plant Region Cultivar Fungicide of tested popula-tions DF DS IZ IA
Sorkhankalate Sante Equation pro 10 34.66 43.04 12.53 1.98
2009 Potato Gorgan Agria Ridomil Gold 10 53.48 51.02 15.67 4.37
Aliabad Saxon Mancozeb 10 53.61 62.31 23.74 7.94
Valikabad Marfona No fungicides 10 70.51 76.96 35.87 19.56
Fazelabad Marfona No fungicides 10 72.92 79.02 37.57 21.82
2009 Kafshgiri Early girl No fungicides 13 60.30 70.31 98.11 41.60
Tomato Yassaghi Endemic No fungicides 17 52.22 62.43 86.08 28.44
Sorkhankalate Draga Equation pro 10 37.29 38.77 12.80 1.87
2010 Potato Gorgan Agria Ridomil Gold 5 44.29 46.55 15.20 3.16
Aliabad Saxon Copravit 5 53.54 59.99 20.88 6.76
Valikabad Marfona No fungicides 5 63.49 66.81 30.66 13.24
Fazelabad Marfona No fungicides 8 69.88 77.07 34.43 18.71
2011 Potato Valikabad Concord Equation pro 15 19.06 18.64 6.10 0.29
Fazelabad Marfona Equation pro 15 30.89 36.19 11.59 1.36
Sorkhankalate Sante Equation pro 10 22.68 15.80 5.98 0.23
lsd05 2.218 2.852 2.343 1.877
Correlation analysis indicated extremely high significant correlations between all investigated features (table 3). This contradicts to the results obtained for Moscow Region where the correlation level was essentially lower and can be explained as influence of extremely wet climate of area close to the Caspian Sea. Under conditions of the Moscow Region the continental climate influences the P infestans field populations in a different other way.
T a b l e 3
Means of correlation coefficients (right from diagonal for potato P. infestans populations, left from diagonal for tomato P. infestans populations
IA DF DS IZ
IA — 0,903 ± 0,017 0,910 ± 0,015 0,975 ± 0,004
DF 0,976 ± 0,009 — 0,968 ± 0,006 0,945 ± 0,010
DS 0,990 ± 0,004 0,956 ± 0,016 — 0,962 ± 0,007
IZ 0,968 ± 0,012 0,906 ± 0,033 0,956 ± 0,016 —
All investigated P infestans field populations were asexual with different levels of formation of zoosporangia. Weak and asexual strategies of reproduction were revealed (table 4). Cluster analysis on strategies of reproduction clearly indicated three kinds of P infestans populations (fig. 3).
T a b l e 4
Strategies of reproduction (SR) and viability support (SVS) for groups of potato and tomato field P. infestans populations
Strategies
SR SVS
Year, Number of tested populations
Host plant Region Cultivar Fungicide Type % Type %
Sorkhankalate Sante Equation pro 10 W1 100 W1 100
Gorgan Agria Ridomil Gold 10 W1 100 W1 100
2009 Aliabad Saxon Mancozeb 10 W1 A1 20 80 W1 100
Potato Valikabad Marfona No fungicides 10 A1 A4 90 10 A1 100
Fazelabad Marfona No fungicides 10 A1 A4 60 40 A1 A4 80 20
2009 Tomato Kafshgiri Yassaghi Early girl Endemic No fungicides No fungicides 13 17 A7 A7 100 100 A4 A1 A4 100 41 59
Sorkhankalate Draga Equation pro 10 W1 100 W1 100
Gorgan Agria Ridomil Gold 5 W1 100 W1 100
2010 Aliabad Saxon Copravit 5 W1 A1 20 80 W1 100
Potato Valikabad Marfona No fungicides 5 A1 100 W1 A1 20 80
Fazelabad Marfona No fungicides 8 A1 A4 75 25 A1 100
2011 Potato Valikabad Concord Equation pro 15 W1 100 W1 100
Fazelabad Marfona Equation pro 15 W1 100 W1 100
Sorkhankalate Sante Equation pro 10 W1 100 W1 100
The first kind is characterized by the weak strategy and includes potato populations of different origin (year of collection, location and cultivar), but all of them were treated with fungicides Ridomil Gold or Equation pro.
The second kind is characterized by both weak substrategy W1 and asexual substrategies A1, A4 in different ratios. This kind includes potato populations of different origin (year of collection, location and cultivar) not treated with fungicides Ridomil Gold or
Tree Diagram for 15 Variables Ward's method Euclidean distances
2009 Potato Sorkhankalate Sante Equation Pro
2009 Potato Gorgan Agria Ridomil gold
2010 Potato Sorkhankalate Draga Equation Pro
2010 Potato Gorgan Agria Ridomil Gold 2011 Potato Valikabad Concord Equation Pro 2011 Potato Fazelabad Marfona Equation Pro
2011 Potato Sorkhankalate Sante Equation Pro
2009 Potato Aliabad Saxon Mancozeb 2010 Potato Aliabad Saxon Copravit 2009 Potato Valikabad Marfona No fungicides 2010 Potato Valikabad Marfona No Fungicides
2009 Potato Fazelabad Marfona No Fungicides
2010 Potato Fazelabad Marfona No Fungicides 2009 Tomato Kafshgiri Early girl No Fungicides 2009 Tomato Yassaghi Endemic No Fungicides
0 100 200 300 400 500 600 700 800
Linkage Distance
Fig. 3. Tree diagram for groups of potato and tomato field P infestans populations according to their
strategies of reproduction
Equation pro. At analysis of this group it is possible to distinguish subclaster with two groups of populations treated with Coprovit and Mancozeb.
The third kind is characterized by strong asexual substrategy A7 and includes only tomato populations.
All investigated P infestans field populations have rather different level of aggressiveness. Weak and aggressive strategies of viability support were revealed (table 4). Cluster analysis on strategies of viability support clearly indicated two kinds of P. infestans populations (fig. 4).
The first kind is characterized by weak substrategy W1 and includes potato populations of different origin (year of collection, location and cultivar), but all of them were treated with fungicides.
The second kind is characterized by both weak strategy and aggressive substrategies A1, A4 in different ratios. This kind includes potato populations of different origin (year of collection, location and cultivar) not treated with fungicides. At analysis of this group it is possible to distinguish subclaster with populations not treated with fungicides and subclaster with tomato populations.
It is interesting and important that no P infestans oospores were detected in spite of the fact that many samples of blighted leaves were monitored and both A1 and A2 mating
Tree Diagram for 15 Variables Ward's method Euclidean distances
2009 Potato Sorkhankalate Sante Equation Pro - -
2009 Potato Gorgan Agria Ridomil gold ■ -
2009 Potato Aliabad Saxon Mancozeb - -
2010 Potato Sorkhankalate Draga Equation Pro ■ -
2010 Potato Gorgan Agria Ridomil Gold - -
2010 Potato Aliabad Saxon Copravit - -
2011 Potato Valikabad Concord Equation Pro ■ -
2011 Potato Fazelabad Marfona Equation Pro - -
2011 Potato Sorkhankalate Sante Equation Pro - -
2009 Potato Valikabad Marfona No fungicides ■ -
2010 Potato Fazelabad Marfona No Fungicides - -
2009 Potato Fazelabad Marfona No Fungicides - -
2010 Potato Valikabad Marfona No Fungicides ■ -
2009 Tomato Kafshgiri Early girl No Fungicides - -
2009 Tomato Yassaghi Endemic No Fungicides - -
0 100 200 300 400 500 600 700 800
Linkage Distance
Fig. 4. Tree diagram for groups of potato and tomato field P infestans populations according to their
strategies of viability support
types were found in Golestan Iran (Zolfaghary A., unpublished data). This demands additional consideration.
The obtained results indicate to a quite strong level of late blight development in Iran Golestan both on potato and on tomato in spite of a rather warm climate. Susceptible potato cultivars without treatments were strongly blighted. Treatment with fungicides Ridomil Gold and Equation pro provided good protection against late blight as almost all P infestans populations treated with these fungicides demonstrated suppressed features. Coprovit and Mancozeb were not so effective because these fungicides did not much suppress asexual stage of P infestans in Golestan Iran.
Also it is important that imported tomato (Early Girl) was affected by late blight than local tomato. This supports the concept that imported host plants are affected by diseases stronger than the local aboriginal host plants. So imported host plants can be very dangerous for local aboriginal species as a source of infection [4].
Conclusions
Late blight is proved to be a very serious disease of potato and tomato in Iran. This disease can disturb ambitious plans to increase potato production and consuming for Iran population.
Late blight of potato and tomato is needed to be protected with modern fungicides. Otherwise, the crops would be highly suppressed with asexual P. infestans populations with different level of aggressiveness (including very aggressive populations under the Golestan conditions).
This investigation has clearly demonstrated that in spite of the current climate warming P infestans still can be very dangerous pathogen which must be carefully monitored both in Iran and in Russia.
References
1. Habibi J., Hadjianfar R., Mirkamali H. Major pests, diseases and weeds of potato in Iran and their integrated management. Iran Ministry of agriculture, 2010. 152. P. 84-103.
2. Smirnov A.N., Kuznetsov S.A. Determination of strategies of reproduction and viability of field Phytophthora infestans populations // Izvestiya TSHA, 2006. No 4. P. 28-41 (Russian).
3. Smirnov A.N., Kuznetsov S.A. Reproductive strategies of field Phytophthora infestans populations // Proc. Nat. Sci. Matica Srpska, Novi Sad, 2009. No 116. P. 149-157.
4. Smirnov A.N., Kuznetsov S.A., Kuznetsova O.G. Development of epiphytoties on relatively closed species of host plants // Doklady TSHA, 2011. Is. 282. P. 292-305 (Russian).
5. Zargarzadeh F., Ghorbani A., Asghari A., Nouri - Ganbalani G. The effect of climatic factors on potato late blight in Ardebil plain of Iran // Journal of Food, Agriculture & Environment. 2008. Vol. 6 (3, 4). P. 200-205.
6. Zolfaghary A., Antonenko V.V., Zaytsev D.V., Ignatenkova A.A., Mamonov A.G., Penkin R.V., PoshtarenkoA.Yu., Smirnov A.N. Development of late and early blight on potato and tomato in the Moscow Region under abnormal weather // Zashita i karantin rastenij, 2011. No 11. P. 40-42. (Russian).
7. http://www.portalostranah.ru/view.php?id=219
8. http://farhang.al-shia.ru/ir_sov.html
СТРАТЕГИЯ РАЗМНОЖЕНИЯ И ПОДДЕРЖАНИЯ ЖИЗНЕСПОСОБНОСТИ ООМИЦЕТА
PHYTOPHTHORA INFESTANS В ИРАНЕ
Аннотация: статья посвящена жизненному и инфекционному циклам Phytophthora infestans (Mont.) de Bary в иранской провинции Голестан. 3255 образцов листьев картофеля и томата, пораженных фитофторозом, собрали в 2009-2011 гг. из частных полей (0,5-4 га) 7районов. Всего изчили 123 полевых популяции патогена с картофеля и 30 - с томата. Максимальные значения по распространенности, развитию, индексам встречаемости зооспорангиев и агрессивности зарегистрировали для полевых популяций патогена, против которых не применяли фунгициды. Наиболее агрессивными были популяции P infestans на неместном сорте томата Early Girl. Напротив, вышеупомянутые показатели были низкими для картофельных популяций P infestans, против которых применяли фунгициды Equation pro и Ridomil Gold. Все исследованные популяции P infestans были бесполыми с различной интенсивностью образования зооспорангиев. Ооспоры не обнаружили. Полученные результаты убеждают в том, что, несмотря на потепление климата, P. infestans остается опаснейшим патогеном картофеля и томата и должен четко контролироваться как в Иране, так и в России.
Ключевые слова: Phytophthora infestans, фитофтороз картофеля, фитофтороз томата, Иран, Голестан, зооспорангии, стратегии размножения, стратегии поддержания жизнеспособности.
Автор для корреспонденции: Смирнов Алексей Николаевич - д. б. н., проф. каф. защиты растений РГАУ-МСХА имени К. А. Тимирязева; e-mail: smimov@timacad.ru
