Identification of a molecular marker linked to Septoria nodorum blotch resistance in Triticum tauschii using F2 bulked segregant

Abstract

A search was conducted for a molecular marker linked to a gene for resistance to septoria nodorum blotch in the Triticum tauschii accession RL5271. DNA was extracted from leaves of F2 plants which were progeny tested to identify homozygous resistant and homozygous susceptible F2 plants. The DNA from the homozygous resistant plants was pooled together and the low copy sequences were enriched using renaturation kinetics and hydroxyapatite to remove the repetitive DNA sequences. The pooled DNA from the homozygous susceptible plants was treated in the same manner. The pooled DNA and the parental DNA were screened using RAPD primers. Two markers present in the pooled resistant DNA and in the parental DNA were identified and cloned. These markers were verified using RFLPs with the cloned marker as a probe. One of the probes did not produce any polymorphism as a RFLP, even when a number of different restriction enzymes were used. The second marker was polymorphic between the two parents when the DNA was restricted with HindIII and then MseI. In the 14 homozygous F2 plants tested, the marker was completely linked to the resistance gene. This marker may be valuable in introgressing the resistance gene from T. tauschii into a commercial bread wheat cultivar