Int.J.Curr.Microbiol.App.Sci (2019) 8(12): 621-627 International Journal of Current Microbiology and Applied Sciences ISSN: 2319-7706 Volume 8 Number 12 (2019) Journal homepage: http://www.ijcmas.com Original Research Article https://doi.org/10.20546/ijcmas.2019.812.081 Pathogenicity Diversity in Albugo candida Isolates causing White Rust Disease in Rapeseed-Mustard Devanshu Dev*, G. R. Daniel, Pooja Upadhyay and A. K. Tewari Department of Plant Pathology, College of Agriculture, G B Pant University of Agriculture and Technology, Pantnagar-263145, Uttarakhand, India *Corresponding author ABSTRACT Albugo candida causing white rust of rapeseed-mustard is a highly variable fungus and cause great economic losses. In this study 44 A. candida isolates belongs to 17 different states of India has been used for the pathogenicity K e yw or ds diversity. Symptomatology of the pathogen i.e. pustule pattern, pustule size Coalesced , and pustule colour has taken as criteria for the pathogenicity diversity. All the Pathogenicity diversity, Oilseed 44 A. candida isolates were inoculated on susceptible Brassica juncea cultivar crop, Biotic stress, Varuna for the study. In the study of white rust symptoms of 44 A. candida on White rust Varuna cultivar five different types of pustule pattern has been observed viz. Article Info viz. Separate circular; Coalesced circular, Scattered and pin head; Restricted near veins and veinlets and Restricted near veins and veinlets separate or Accepted: coalesced circular type pustules. Pustules size among 44 A. candida isolates 07 November 2019 Available Online: was varied from 0.5-2.5mm while pustule colour of all the isolates was creamy 10 December 2019 white. The study very less pathogenicity diversity in pustule size and colour has been observed among 44 A. candida isolates, while in pustule pattern some diversity was observed. Introduction losses from 20-60 per cent (Kolte, 2002; Khunti et al., 2003; Sachan et al., 2004; Oilseed brassica is one of the most important Kumar and Kalha, 2005) and up to 36.88 per oilseed crop of tropical and subtropical cent (Bal and Kumar, 2014) in mustard. White countries. Rapeseed-mustard affected by rust symptoms are characterised as local and different biotic stress, among them white rust systemic. In case of local infection, symptoms caused by A. candida is a major disease, of the disease appear primarily on the lower causing heavy economic losses. It is estimated surface of leaves and manifested by the that the floral and leaves infection can cause appearance of minute or small, white or 621 Int.J.Curr.Microbiol.App.Sci (2019) 8(12): 621-627 creamy yellow raised scattered and circular Materials and Methods pustules (1 to 2 mm in dia.) which later coalesce to form patches. Systemic infection Forty four A. candida isolates collected from symptoms include distortion, hypertrophy, Oilseed Pathology Laboratory, Department of hyperplasia and inflorescence sterility. This Plant Pathology were belonging to 17 states of infection phase has been known as the stag India and also from 10 different Brassica spp. head. The description of A. candida isolates used in the studies is given in the table below (Table The flowers affected show malformation, the 1). petals become green sepals and the stamens can be transformed into a leaf-like structure or Isolation and purification of white rust a carpel. inoculum The petals and stamens persist in the flower, The isolation and purification of all A. as in normal flowers, rather than falling early. candida isolates were done on susceptible B. Sometimes the stamens become thick club- juncea cv. Varuna grown under glasshouse. shaped sterile bodies. Usually the ovules and The seedlings were raised in plastic pots pollen grains are atrophied and result in containing sterilized soil. The fresh incomplete sterility (Kolte, 1985). Yield loss sporangial suspension was prepared with is greater in case of systemic than local single pustule in a glass vial contained 1-2ml infection (Harper and Pittman, 1974; Petrie, sterile distilled water. The suspension was 1973; Verma and Petrie, 1980). At maturity mixed properly and kept it at 10°C for stage, stag heads are with thick-walled brown overnight for the release of zoospores. oospores that have been appeared to survive in Although, freshly prepared sporangial dry form for a more than 20 years (Verma and suspension has also used for the inoculation Petrie, 1975). without any incubation period. The sporangial concentration in the suspension A. candida isolates from different was maintained about 2.5×105 zoosporangia geographical regions and different host may per ml using haemocytometer. The seedlings be different in their incubation period, latent at cotyledonary stage (7-8DAS) were period and production of sporangia and inoculated with 10μl spore suspension zoospores, pustule size, shape and texture and through inoculating micropipette on each aggressiveness (Lakra and Saharan, 1988; and every lobes of cotyledon of the Gupta and Saharan, 2002; Patni et al., 2005 seedlings. After inoculation plants were and Mishra et al., 2009). This indicated that transfer to plant propagator box and kept the there may be the possibilities of variability box in a dark room for 72hrs, with a relative within A. candida isolates. The high humidity of more than 90 per cent and of variability of A. candida makes it a highly 18±20C temperature. After three days plants virulent pathogen, which is difficult to were taken out and kept in glasshouse manage. The study of variability is needed to where, proper temperature (18±20C) and find out the status of variability, there humidity (>80%) were maintained during occurrence and evolution pattern so that it will the entire plant growth and disease be helpful in the development of resistant appearance period. When disease appeared varieties against the disease. Therefore, in this (10-15DAI), infected leave samples were study pathogenicity variability of 44 A. collected before yellowing of the leaves and candida isolates has been done. preserved at low temperature (4°C- 10°C) by 622 Int.J.Curr.Microbiol.App.Sci (2019) 8(12): 621-627 keeping it in butter paper bags for further observations has been reported by Pandey et studies. The pustule pattern of all 44 A. al., (2013) where pinhead raised pustules were candida isolates were observed and observed in isolates of Pantnagar, Delhi, recorded. Likewise, pustule dia. of 10 Bharatpur, Hisar, Kangra, and Jammu, while randomly selected leaves of an isolate were pinhead scattered pustules in isolates of taken in mm. Analysis of mean pustule size Ludhiana. Based on pustules pattern 33 A. of all 44 A. candida isolates has been done candida isolates were grouped in 05 through Duncan’s Multiple Range Test pathotypes. (DMRT) using SPSS 16.0 version software to find out whether there is significant difference In Duncan’s multiple range test (DMRT) of between the mean pustule size. Pustule colour mean pustule size of A. candida isolates varied in symptomatic leaves of each isolate was from 0.5-2.5mm in dia. The lowest mean observed and recorded. pustule size i.e. 0.5mm dia. was observed in Ac-MMP (B. juncea cv. Maya, Morena, MP) Results and Discussion while, highest mean pustule size i.e. 2.5mm dia. was observed in Ac-BjV (B. juncea cv. The pathogenicity diversity of 44 A. candida Varuna, Pantnagar, Uttarakhand), Ac-Knp isolates has been done on the B. juncea cv. (Kanpur, UP) etc. The mean pustule size was Varuna. The colour of pustules of all the 1.59mm dia. In DMRT of mean pustule size of isolates was creamy white in colour. The 44 A. candida isolates, less variability has pustule pattern of all the isolates has been been observed (Table 3). observed visually and categorized in 05 different types of pustule pattern viz. Separate The similar type of observations has been circular; Coalesced circular, Scattered and pin reported by Pandey et al., (2013) the small head; Restricted near veins and veinlets and size pustules (0.5-1.5 mm) was observed in Restricted near veins and veinlets separate or New Delhi and Hisar isolates of A. candida, coalesced circular type pustules. while large size pustules (1-3 mm) in Pantnagar and Ludhiana isolates of A. Nine showed separate circular type, 16 of candida. coalesced circular type, 12 of scattered pin head type, 04 of restricted near vein and In this study pathogenicity diversity of A. veinlet type and 03 of restricted near vein and candida isolates has been observed based on veinlet separate or coalesced circular type of symptomatological observations. The pustule (Table 2). significant diversity has been observed in pustule pattern of different A. candida isolates The variation in pustule pattern of 33 A. which could be utilized for the further study. candida isolate indicated different level of While, in case of pustule colour and pustule pathogenicity diversity. The isolates that size of A. candida isolates, there was no formed different pustule pattern could be of significant difference observed. different pathotypes. The similar type of 623 Int.J.Curr.Microbiol.App.Sci (2019) 8(12): 621-627 Table.1 S.No. Isolate Host Place State Latitude & Name Longitude 1. Ac-BjV B. juncea cv. Varuna Pantnagar Uttarakhand 29° 02' 60" N 2. Ac-Brai Banarasi rai 79° 30' 59" E 3. Ac-Brys B. rapa yellow sarson 4. Ac-BjBio B. juncea cv.Bio-YSR 5. Ac-Br B. rugose 6. Ac-Bni B. nigra 7. Ac-Bna B. napus 8. Ac-BjK B. juncea cv.Kranti 9. Ac-Orai Ornamental rai 10. Ac-Kw Kattili weed 11. Ac-Knp B. juncea Kanpur Uttar Pradesh 26°26'59.6"N 80°19'54.8"E 12. Ac-Met B. juncea Meerut 28° 59' 4'' N 77° 42' 21'' E 13.