Indian Phytopath. 62 (4) : 424-428 (2009) *Corresponding author: resmi_jayee@rediffmail.com Screening somaclones of ginger (Zingiber officinale) for bacterial wilt disease RESMI PAUL*, M.R. SHYLAJA 1 and KOSHY ABRAHAM 2 1 Department of Plantation Crops and Spices; 2 Department of Plant Pathology, College of Horticulture, Kerala Agricultural University, Thrissur 680 656 ABSTRACT: One hundred and fifty one somaclones of ginger cvs. viz., Maran and Rio-de-Janeiro regenerated through bud culture were screened against bacterial wilt disease caused by Ralstonia solanacearum at College of Horticulture, Kerala Agricultural University, Thrissur, Kerala, India during 2003 to 2005. Three screening methods viz., planting in sick field, inducing electrolyte leakage using toxic metabolite(s) of the pathogen and artificial inoculation of clones with Ralstonia solanacearum were adopted. In natural screening in sick field, 13 % of somaclones were not affected by any diseases of ginger and survived in sick field. In screening by electrolyte leakage method using toxic metabolite(s) of Ralstonia solanacearum, 14 per cent of somaclones screened exhibited low leakage of electrolytes as compared to conventionally propagated plants. In artificial inoculation of the bacterial wilt pathogen, all the clones took infection, but subsequent germination of rhizomes was observed in four somaclones viz., 970 M, M VI, 364 R, and R XI. Somaclones of Maran were found resistant to the disease as compared to clones of Rio-de-Janeiro. Based on reaction of ginger somaclones to different screening methods and evaluation for yield, three somaclones viz., 970 M, M VI, and 364 R, with high yield showing resistance to bacterial wilt disease could be located which could be used for further field evaluation / production programmes. Key words: Artificial screening, electrolyte leakage, natural screening, somaclones Diseases like soft rot caused by Pythium aphanidermatum and bacterial wilt caused by Ralstonia solanacearum are the major constraints in production of ginger (Zingiber officinale Rosc.). Attempts to isolate resistant clones using conventional breeding techniques were not successful in ginger as the genetic variability available for disease resistance is low and all the available cvs. / varieties are susceptible to the diseases. Also, studies were conducted to manage bacterial wilt disease in ginger using cultural, chemical and biological methods and none of the methods gave a satisfactory control of the disease (Kumar and Hayward, 2005). Broadening the genetic base through in vitro culture induced variability and exploitation of somaclonal variation for isolation of desirable plant types are of great significance in crop improvement programmes of ginger. Hence, investigations were undertaken at College of Horticulture, Kerala Agricultural University, Thrissur, Kerala, India to screen somaclones of ginger regenerated through bud culture against bacterial wilt disease. MATERIALS AND METHODS Somaclones of two ginger cvs. viz., Maran and Rio-de-Janeiro derived through in vitro adventitious bud regeneration after passing through 10 to 12 subculture cycles and planted out during 1999- 2000 for rhizome development, formed the base material for the study. Somaclones were screened for resistance to bacterial wilt disease by three methods viz., screening in sick field, inducing electrolyte leakage from leaves using toxic metabolite(s) of pathogen and artificially inoculating clones with bacterial wilt pathogen. Conventionally propagated (CP) plants of cvs. Maran and Rio-de- Janeiro served as control.