INTERNATIONAL JOURNAL OF BIO-RESOURCE, ENVIRONMENT AND AGRICULTURAL SCIENCES (IJBEAS)

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1 INTERNATIONAL JOURNAL OF BIO-RESOURCE, ENVIRONMENT AND AGRICULTURAL SCIENCES (IJBEAS) Vol. 2(1): , // ISSN SUSTAINABLE MANAGEMENT OF CLUBROOT DISEASE [PLASMODIOPHORA BRASSICAE (WORONIN) OF BRASSICAS IN WEST BENGAL 1 Indrabrata Bhattacharya and 2 Bholanath Mondal 1 Department of Plant Pathology, Faculty of Agriculture, Bidhan Chandra Krishi Viswavidyalaya, Mohanpur , Nadia, West Bengal, 2 Department of Plant Protection Palli-Sikha Bhavan,, Viswa-Bharati, Sriniketan, Birbhum, West Bengal Corresponding author: bholanath.ppvb@gmail.com Received: January 2016 Revised accepted: February 2016 ABSTRACT Clubroot disease caused by soil borne obligate biotrophic protist Plasmodiophora brassicae (Woronin) is a devastating disease of brassica vegetables and oilseeds occurring worldwide. Disease is particularly prevalent in temperate climates but it appears wherever brassicas are grown even in tropical zones if the soil is acidic and poorly drained. Clubs form on primary and secondary roots leading to irreversible foliar wilting and ultimate plant death. P. Brassicae has a three stage lifecycle: first survival in soil as resting spore, second root hair infection by primary zoospores released after germination of resting spores under favourable soil and environmental condition and third cortical infection by (secondary) zoospores ultimate results in formation of resting spores on clubs developed on primary and secondary roots. In India clubroot has spread on cabbage and cauliflower for nearly 80 years in the Eastern Himalayan Darjeeling hills of West Bengal and South Indian Nilgiri hills in Tamil Nadu. Since the early 1980s this pathogen has spread rapidly on rape and mustard grown in red and lateritic soil regions of West Bengal. At present clubroot disease is spreading at an alarming rate in the plains of north and south of West Bengal and endemic in Darjeeling hills causing substantial damage of brassica cultivation. Chemical control of clubroot disease is difficult due to prolong survival of pathogen as resting spores in soil, high variability of different races and very few varieties of brassicas have shown resistance to the pathogen. Development of resistant lines is difficult due to narrow range of genetic variability of brassica hosts in India and wide variability of pathogen, no resistance source has been found among the cultivated oilseed brassicas and vegetables. All the cultivated brassicas are highly susceptible to club root disease in West Bengal. The plant resistance to disease, although genetically controlled may also be affected by environmental factors. Prolong survival of the pathogen in soil as resting spore is unique features of this disease. Survival of resting spores in soil and subsequent germination and infection process is affected by soil texture and structure; its moisture; temperature; ph; calcium, boron, and nitrogen content; and the presence of active microbial antagonists. Considering the interaction of P. brassicae populations with the soil environment from the perspective of its pathological and biological fitness a prediction model based on inoculum load and soil environmental stress factors could offer means for developing a decision support system for the integrated management of this disease in West Bengal. Key words: Clubroot, Management, Plasmodiophora brassicae, Rape and mustard and Soil abiotic stress and Decision Support System (D.S.S) INTRODUCTION Clubroot of crucifers caused by soil borne obligate biotrophic protest Plasmodiophora brassicae (Woronin) is a devastating disease of brassicas oilseeds and vegetables. It is particularly prevalent in temperate region under diverse soil environmental stress condition and at present it is reported from all the continents of the world including tropical Asia Africa and Latin America. Gradual irreversible wilting, yellowing of leaves and root galling (club formation) on primary and secondary roots of Brassica hosts results in total death of plants within a short time. In West Bengal, Clubroot is known to occur since 1952 and has spread on cabbage in the Darjeeling Hills (Chattopadhyay and Sengupta,

2 1952). Since early 80 s this disease has been spreading at an alarming rate on rape and mustard crop specially in acidic soil regions i.e. red and lateritic region, hilly and terai region of West Bengal (Laha et al., 1985). Crop loss even upto 100% for rape and mustard has been reported in all the districts of West Bengal. Widely cultivated yellow sarson (Brassica rapa var. yellow sarson) cv. Benoy (B-9) has been found to be highly susceptible to clubroot disease in West Bengal (Bhattacharya, 2003). All the cultivated brassica vegetables and oilseeds cultivars have been found susceptible under different agroclimatic zones of West Bengal (Chattopadhyay and Bagchi, 1989; Chattopdhyay et al., 1991; Bhattacharya, 2003). The disease is favored when the temperature fluctuates between 18 and 25 C, the soil is sandy, and the ph is acidic>6.5 (Sen, 2005). Chemical control is difficult due to prolong survival of pathogen up to 15 years in soil, high variability of different races and very few varieties of Brassica have shown resistance to the pathogen (Dixon, 1996). The recommendation to control by crop rotation with non susceptible species and especially the ph increased with liming are emphasized as important measures to reduce inoculum levels in soil (Dixon, 2002). There is a wide difference in population of Plasmodiophora brassicae in different agro-climatic zones of West Bengal. Moreover no resistance sources have been found among the cultivated varieties of brassicas (Chattopadhyay and Bagchi, 1989; Chattopdhyay et al., 1991; Bhattacharya, 2003). The exotic cultivars belonging to B. napus, B. carinata and B. nigra have shown either a resistant or tolerant reaction to disease (Chattopdhyay et al., 1991). The plant resistance to disease, although genetically controlled, may be affected by environmental factors (Dixon, 2009). Mineral nutrition is a factor that can be manipulated in order to control the diseases. The pathogen completes its life cycle in two phases--a primary phase after germination of resting spores in soil occurring in the root hairs and a secondary phase (club formation) in cortical tissue (Woronin, 1878).The short period between germination and penetration is one of greatest vulnerability or weak links in the life cycle of P. brassicae. Survival of pathogen in soil and subsequent infection process is affected by soil texture and structure; its moisture; ph; calcium, boron, and nitrogen content; and the presence of active microbial antagonists. These factors influence the inoculum potential and its viability and invasive capacity of the pathogen. Considering the interaction of P. brassicae with the soil environment from the perspective of its pathological and biological fitness in the proposed programme is an unusual approach for disease management. Rationale Brassica, having 338 genera (Warwick et al., 2006) in the tribe Brassicae of the family Brassicaceae (Rakow, 2004), is agriculturally the most important genus providing the greatest diversity of food products from its 39 species worldwide (Warwick et al., 2006; Dixon, 2006b). For centuries, species in this genus have been a major source of food for humans and fodder for domesticated animals. The seed is a valuable source of high quality edible oil and the seed meal is a high value protein for animal feed. In addition, some species of Brassica have been used as condiments in some Asian countries for centuries. In the western world, prior to World War II, Brassica oil was used as lamp oil as well as lubricant for steam engines (Downey, 1990). In recent development of eco-friendly bio-diesel production brassica oil is one of the important components. New avenues of use of Brassica, especially broccoli, cauliflower, brussels sprouts, collards, kohlrabi and kale are becoming apparent and they are now considered functional food with long-term roles in the fight against cancer (Lampe and Peterson, 2002; Fowke et al., 2003; Brandi et al., 2005) and coronary disease (Dixon, 2006b). In India rapid expansion of brassica cultivated areas related with intensification of high input commercial cultivation like indiscriminate use of fertilizers specially nitrogenous fertilizers caused soil acidity problem which is the major cause of high incidence of clubroot disease(bhattacharya et. al, 2014). This disease has been a longstanding and intractable scourge of vegetable brassica crops and is now also established as the cause of significant losses(10-15%) in oil seed brassica crops. Rape and mustard oil in West Bengal is the single most important and essential source of edible vegetable oils used in daily foodstuffs. Short duration Toria (Brassica rapa) and Yellow sarson (Brassica rapa) and long duration Indian mustard (B. juncea) are the main oilseed Brassica crops cultivated in West Bengal state covering hectares with average seed yield 900 kg ha -1. The production of rape and mustard depends on proper agro-climatic conditions during growing season 217

3 and biotic stresses. Club root- a newly appeared exotic disease introduced from temperate climate causing serious damage. This soil borne disease is considered only constraint for rape and mustard cultivation in acidic soil regions of West Bengal. Host- Pathogen relationship Clubroot disease has a European history dating back to the 13 th century Plasmodiophora brassicae was formally identified as the cause of clubroot byworonin in1878. P brassicae has a three stage lifecycle: survival in soil as resting spore in soil, root hair (primary) infection and cortical (secondary) infection. The classical association of the soil borne microbe, Plasmodiphora brassicae with clubroot disease affecting members of the Brassicaceae established by the Russian biologist M. Woronin (1878). More than a century later, the two phase life history proposed by Ingram and Tommerup (1972) is the most widely accepted. Recent classification of this bio-trophic pathogen belongs to Protist group due to common nature of fungus and Protozoa.The pathogen is under Phylum: Cercozoa, Class: Phytomyxea, Order: Plasmodiophorida, Family: Plasmodiophoraceae. The taxonomy of this organism, even the Kingdom to which it belongs, is the subject of ongoing debate and changes constantly.only two detailed and comprehensive reviews of this host - pathogen combination exist (Colhoun, 1958; Karling, 1968). More than 148 years later much remains unknown about the taxonomy, full lifecycle and interaction of this pathogen with its hosts. Development of geo-pathological map of Plasmodiophora brassicae in West Bengal under different soil environmental stress condition Spatial variability of resting spore population within fields and variations between fields in the occurrence of Plasmodiophora brassicae will be determined by using quantitative PCR -assays. The molecular methods will be validated by traditional bioassay techniques. In the field, the inoculum threshold for disease depends upon a range of site specific factors such as soil physico chemical properties and crop type, climate and cultural practices. Real-time PCR will be used to quantify the inoculum load in soils and predict expected yield loss. Soil will be sampled by using GPS from fields, and geo-reference of the soil where disease occurred will be evident from the map. Species-specific primers will be developed to amplify small regions of P. brassicae ribosomal DNA. Total genomic DNA will be extracted and purified from soil samples using commercial kits, the amount of pathogen DNA will be quantified by using a standard curve. Decision Support System based on soil abiotic stress and pathogen variability A decision support system is a highly flexible and interactive Information Technology system which has a purpose of supporting decision making when the problem is not structured. It forms an association between the decision maker, and specialized support that is provided by it. Such intervention of DSS propose to bring increased productivity, increased understanding, increased speed, increased flexibility, reduced problem complexity, and reduced risk. Manipulation of soil environment and its effect on reduction of inoculum load. The success of P. brassicae is dependent on the density of resting spores, soil type, soil moisture and temperature, soil ph, and host susceptibility. The impact of soil physical and edaphic factors, including boron, calcium, different forms of nitrogen concentrations, and ph, on the growth and reproduction of P. brassicae within host cells will be studied during primary phase of colonization through root hair infection test and secondary phase through club formation study in poly house. Effects of Boron doses and nitrogen sources (N) at different levels of soil ph on the control of clubroot will be investigated in transplants of chinese cabbage grown in field soil. Seedlings were inoculated with a suspension of resting spores of the pathogen at transplanting and assessed for clubroot severity after 45 days..sample will be collected for determining the concentration of N, P, K, Ca, Mg and B in the leaf tissue. 218

4 Generation of site specific decision support system for integrated management of Plasmodiophora brassicae The ability to predict disease and expected yield loss is the foundation upon which an integrated clubroot control strategy can be implemented. In its simplest form this involves a sound knowledge of site history, including the severity of disease in the most recent brassica crop, the rotational history, site preparation, and treatments applied in previous crops. This information is readily available to most growers, but often not recorded. Molecular techniques offer rapid and reliable means for detecting and/or quantifying P. brassicae in the site. Sound local knowledge of factors such as soil type and climatic conditions and basic site history, these techniques can be powerful decision support tools for farmers. The data, information of the various experimental findings and knowledge assimilated thereof, on the Plasmodiophora brassicae brassica system involving brassicas and cole vegetables, will lead to a simple, easy to use PC based decision support system. The proposed system will benefit the end users, researchers and policy makers in agriculture towards forecasts regarding the outbreak of such disease in the various crops across the identified agroclimates and also be a useful tool towards planning for control of the pathogen. Prolong survival of the pathogen upto 15 years in soil Wide range of genotypic variability of Pathogen Why Club root? Change of climate & cropping pattern Soil Abiotic Stress Condition Low ph, B and Ca deficiency 219

5 Lifecycle of Pathogen(Plasmodiophora brassicae) Primary Phase Root hairinfection Secondary phase Fig. 1. Symptoms of clubroot disease of rapeseed REFERENCES Bhattacharya, I Study of race variation and characterization of Plasmodiophora brassicae causing clubroot disease of crucifers in West Bengal (India).Mohanpur, Bidhan Chandra Krishi Viswavidyalaya, Final Report ICAR (Indian Council of Agricultural Research) Adhoc Project. New Delhi, India. Brandi, G., Schiavano, G. F., Zaffaroni, N., Marco, C. De, Paiardini, M., Cervasi, B. and Magnani, M Mechanisms of action and antiproliferative properties of Brassica oleracea juice in human breast cancer cell lines. The Journal of Nutrition 135:

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