Identification of DNA markers for fusarium head blight resistance QTL in wheat cultivars Ning 7840, Freedom, and Patton
Abstract
Fusarium head blight (FHB) caused by Fusarium graminearum is a destructive fungal disease of wheat (Triticum aestivum L.) in humid and semi-humid areas of the world. FHB-resistant cultivars exhibit Type II resistance that limits disease spread in inoculated spikes. Resistance has been shown to be quantitatively inherited with highly resistant cultivars containing several genes. Development of durable and highly resistant cultivars can be facilitated if novel genes with linked molecular markers are identified. Wheat cultivars Ning 7840, Freedom, and Patton are highly to moderately resistant cultivars that have potentially different resistance genes. FHB resistance from Chinese cultivar Ning 7840 was backcrossed into the FHB-susceptible cultivar Clark. BC3F5 plants with different resistance phenotypes were characterized and developed into four lines: a FHB-susceptible line (L1) and three FHB-resistant lines (L2, L3, and L4). Seven recombinant inbred populations were developed by single-seed descent from crosses of L1 X L2, L1 X L3, L1 X L4, Freedom X L1, L1 X Patton, L3 X Patton, and L4 X Patton. Populations were characterized for resistance to spread of FHB in spikes by single-floret inoculation at anthesis with a spore suspension of F. graminearum. Disease spread was determined at 25 days after inoculation as a percentage of diseased spikelets and rachis internodes per spike. Populations, other than those derived from Patton, were evaluated in F5, F6, and F7 generations in two greenhouse trials and one field trial. Patton-derived populations were tested in F3 and F5 generations in field trials. Bulked segregant analysis and QTL mapping by linear regression and interval analysis revealed several simple-sequence repeat (SSR) markers significantly associated with FHB resistance. Four QTL were identified in Ning 7840-derived lines on chromosomes 1B, 3B, and 5B. L2 contains a single QTL on chromosome 313 that was also identified in L3. Additional QTL were identified in L3 on chromosomes 1B and 5B. L4 has a different QTL on chromosome 3BS. QTL were identified on chromosomes 2A, 2B, 3B, and 7B in the Freedom population. The QTL on 3B is in the same genomic region as the QTL in L2 and L3. Patton populations were shown to have two QTL on chromosome 3B and a QTL on 3D. The QTL on 3B are in similar locations to those in L3 and L4. Identification of these genomic regions and molecular markers associated with Type II FHB resistance should be useful in wheat improvement.
Degree
Ph.D.
Advisors
Ohm, Purdue University.
Subject Area
Agronomy
Off-Campus Purdue Users:
To access this dissertation, please log in to our
proxy server.