Molecular Analysis And Mapping Of Fusarium Wilt Tolerance In Banana Musaspp

Abstract

The study began with a screening technique involving macropropogation technique, newlineto multiply and screen for the segregating pattern among the F1 mapping population newline( Calcutta-4 x Kadali ) and also to estimate the Disease Severity Index (DSI) for the newlineparental lines and mapping population by an artificial inoculation method. Through this newlineexperiment, 89 F1 hybrids were infected with Foc 1 by artificial inoculation and screened newlineafter 45 days. The plants were observed for infection by cutting the corm and pseudostem, and newlinethe disease incidence was scored (0-5 scaling) and grouped as resistant/ tolerant/moderately newlinesusceptible/susceptible and highly susceptible. Simultaneously, phenotypic parameters like newlinephotosynthetic rate (A), transpiration rate (E), stomatal conductance (gs), Leaf temperature newline(LT) were also observed and noted for control and infected plants and analyzed as the fungus newlineattacks the vasculartissues. newlineSecondly, this study also focused on development of genetic map and identification of newlineassociated QTLs using SSR markers, which could facilitate to recognize and map genes newlineunderlying the quantifiable traits. These could further help in gene identification / QTLs newlineassociated with FW tolerance as well as few phenotypic traits for undertaking extensive newlinemolecular breeding in banana. Here, in this study DNA was extracted from parental newlinegenotypes and 94 F1 progenies that are individuals obtained from a cross betweentwo newlinecontrasting genotypes wild M. acuminata Calcutta-4 and cultivar M. acuminata Kadali . newline315 SSR markers were screened for parental polymorphism and 138 were found to be newlinepolymorphic among the parents. Of the 138 markers used for mapping sixty two markers newlinewere mapped on eleven Linkage groups (LGs) spread across a length of 1819.8 cM with a newlinemaximum distance of fifty and six putative QTLs for Fusarium wilt resistance were newlineidentified for five traits (Photosynthesis, Transpiration, Stomatal conductance, Leaf symptom newlineindex and Rhizome discolouration index) with 11.0 to 13.3 % phenotypic effect (R2 newline) and 2.07 newlinetmaterials offer a valuable source for the identification of major genes associated with defense newlineresponse to Fusarium wilt. newlineFurther, it is also seen that, when plants are challenge inoculated with the fungal newlinepathogens, such as the Foc, plants generally respond by switching on a collection of genes newlineresponsible for defense either by producing defensive proteins directly or leading to a series newlineof pathways leading involved in production of certain chemicals that bring about inhibition newlineand thus suppress and restrict the entry of the pathogen. Here, the study revealed the changes newlinein gene expression patterns involved in various functions upon Foc infection. Which mainly newlineincluded miRNAs-Targets, Autophagy, Effector and R-genes (defense genes) that were newlineinvolved in ROS scavenging, cell wall strengthening, Ca2+ signalling, ubiquitination, newlinephotosynthesis and various transcription factors that involve in different signal transduction newlinepathways. The early and increased expression of prominent defense-related genes; newlinemaintenance of cell turgor; maintenance of transpiration, photosynthesis and stomatal newlineconductance rate and increased activity of proteins noted in tolerant genotype Calcutta-4 newlineduring Foc infection might be the possible reasons for tolerancenature.