Biochemical and Pathogenic Variation Among the Isolates of Xanthomonas axonopodis pv. citri from Agro Climatic Regions of India Katkar Madhuri*, Raghuwanshi K.S., Borkar S.G. Department of Plant Pathology and Agriculture Microbiology, MPKV, Rahuri, Dist Ahmednager, M.S. *email: madhurikatkar01@rediffmail.com
Online published on 2 January, 2017. Abstract A total of fifteen isolates of Xanthomonas axonopodis pv. citri (Xac) were isolated from fourteen Agro climatic regions of India and subjected to pathogencity, hypersensitivity and biochemical tests. The pathogenic variability amongst the isolates of Xac was studied on four different Acid lime varieties viz.Sai Sharbati, Phule Sharbati, Pramalini and PKM-1 by detached leaf assay. The isolate from West Bengal (Xac-III) and Nagpur Maharashtra (Xac-VII) were found highly virulent, the symptoms appeared within 10 days of inoculation. The isolates from Uttarakhand (Xac-I) and Meghalaya (Xac-II) were found less virulent showed late appearance of symptom i.e. 20 days after inoculation. On the basis of days required for first appearance of symptoms all isolates were grouped under 3 categories viz. Less Virulent, Moderately Virulent and Highly Virulent. The isolate Xac-I and Xac-II were grouped as less virulent, isolates Xac-IV, Xac-VI, Xac-VIII, Xac-IX, Xac-X, Xac-XIIA and Xac-XIIB were grouped as moderately virulent and isolates Xac-III, Xac-V, Xac-VII, Xac-XI, Xac-XIII and Xac-XIV were grouped as highly virulent. The isolates from Agro-climatic region I and II falls under less virulent group. The isolates from Agro-climatic region IV, VI, VIII, IX, X and XII falls under moderately virulent group and the isolates from Agro-climatic region III, V, VII, XI, XIII and XIV falls under highly virulent groups. The hypersensitivity response of all 15 isolates was reported on tobacco plants (Nicotiana tabaccum). All the isolates showed positive reaction within 24 hrs after inoculation with browning and necrotic lesions. All the 15 isolates were found rod shaped, gram-ve, with colony colour ranging from pale yellow to dark yellow. The isolate were positive for Catalase, KOH and H2S production, hydrolyse starch and gelatin liquefaction. All isolates produce acid from Trahalose. The isolates Xac-IV, Xac-VI, Xac-X, Xac-XIIB produced acid from Arabinose. The isolate Xac-I, Xac-IX utilized cellobiose for acid production whereas the Xac-I, Xac-II, Xac-VI, Xac-VII, Xac-IX, Xac-X, Xac-XI, Xac-XIIB produced acid from fructose; which indicates variation among the isolates. Top Keywords Xanthomonas axonopodis pv. citri, H2S production, gram staining, gelatin liquefaction, pathological variation. Top |