Pathinettil Raj, Rahul

English

Tomato (Lycopersicon esculentum) is the most widely grown vegetable food crop in the world. Late blight (LB) caused by Phytophthora infestans (Mont.) de Bary is a major cause of crop loss in tomato and potato around the globe (Foolad et al. 2008 & Nowicki et al. 2013). LB control by cultural practices alone is insufficient (Chen et al. 2008). In addition, fungicide measures cannot be used when tomatoes are harvested for the fresh market leading to fungicide residues (Horneburg and Myers, 2012).
The project started with 7 late blight resistant genotypes as using parents for initial crosses. These 7 parent genotypes were selected from 3 different groups a.k.a. Organic Outdoor Tomato Project (Uni of Göttingen), Commercial hybrids and Exotic genotypes. 13 F2 populations resulted from these parents used in the year 2016 for screening for late blight.  Out of these, 6 populations were decided to repeat in the year 2017 for a better phenotyping and 1 population which showed a positive transgression (more resistant F2 individuals than both the parents) were chosen for further phenotyping and genotyping in the year 2017.
The genotyping was done using the SolCAP 10K array provided by Illumina which contains 7720 SNP markers. A linkage map was constructed using JoinMap®5. Composite Interval Mapping was done in R package ‘R/qtl’ (Broman et al. 2003). A major QTL on chromosome 9 was found across locations and traits. The phenotypic variation caused by the QTL ranged from 48.3% to 79.3%.
Apart from the main trials, there were 2 sub-trials. Sources of Known Resistance; a group of 17 genotypes known for late blight resistance and TGRC, UC Davis germplasm, with known resistant genes such as Ph1, Ph2 and Ph3. These trials were meant to understand the disease severity and the efficiency of known resistant genes under test conditions. Only Ph3 gene was found to be resistant under the test conditions. It is necessary to search for new sources of resistances against late blight considering the evolutionary potential of the pathogen

Georg-August-University Göttingen

Characterization of novel sources of resistance to  Phytophthora infestans (late blight) in organic fresh market tomato

https://ediss.uni-goettingen.de/bitstream/21.11130/00-1735-0000-0005-127D-B/1/Thesis%202019.pdf

Characterization of novel sources of resistance to Phytophthora infestans (late blight) in organic fresh market tomato

Abstract

Similar works

Full text

Available Versions

Georg-August-University Göttingen