Abstract
Tolerance to pink snow mold caused by Microdochium nivale appears after a cold-hardening period and it is an essential, genotype-dependent, complex quantitative trait for the wintering of triticale (x Triticosecale) and other cereals. Despite long-term studies, a marker for the selection of the tolerant genotypes is still insufficiently recognized. Chlorophyll fluorescence has been reported as a sensitive indicator of stress effects on photosynthesis and can be used to predict plant tolerance. In this study, the genomic regions (QTLs) associated with the level of winter triticale seedlings damage caused by M. nivale infection as well as photosynthesis quantum efficiency and chlorophyll a fluorescence parameters were identified in seedlings of mapping population of 89 doubled haploids lines (DHs) derived from F1 hybrid of cv. ‘Hewo’ and cv. ‘Magnat’ accompanied with the genetic map consisting of 20 linkage groups with a total map length 4997.4 cm. Independent experiments performed in controlled conditions revealed 13 regions identified by a composite interval mapping, located on 7A, 1B, 2B, 6B, 7B, 3R, 5R, and 6R linkage groups and related to the PI, PIABS, TRo/CS, ABS/CS, ABS/CSm, ABS/RC, and Qy values as well as M. nivale tolerance T and susceptibility level P expressed by the seedling damage index. Additionally, candidate genes were in silico identified with the sequence position on wheat (2B and 7B) and rye (5R) chromosomes, where relevant QTL regions were found. The most important candidate genes indicated for M. nivale tolerance of cold-hardened triticale seedlings include those coding: sterol 3-beta-glucosyltransferase UGT80A2-like, transcription factor NAI1-like, and flavonol3-sulfotransferase-like proteins on chromosomes 2B and 5R.
Highlights
Triticale (x Triticosecale Wittm.) originates from a cross between wheat and rye [1,2]
A total of 19 significant QTL effects were identified with the composite interval mapping (CIM) method for P2011, P2012, P2013, T2011, T2012, and T2013, as well as PI, performance index calculated on an absorption basis (PIABS), TRo/CS, absorbed energy flux per CS (ABS/CS), ABS/CSm, ABS/reaction centers (RCs), and Qy2012 traits of triticale seedlings (Table 1)
Two independent QTLs were assigned to unhardened plants on chromosomes 1B and 7B and eleven QTLs were identified in cold-acclimated seedlings on chromosomes 7A, 1B, 2B, 6B, 7B, 3R, 5R, and 6R
Summary
Triticale (x Triticosecale Wittm.) originates from a cross between wheat and rye [1,2] It contains wheat (AABB or AABBDD) and rye (RR) genomes, whereas the D genome is eliminated during the breeding process. It has a higher tolerance than wheat and rye to many fungal diseases [4,5,6] and its grain contains a higher level of essential amino acids than wheat [7]. M. nivale may cause a leaf blotch and stem rot It co-exists in a fungal complex resulting in fusarium ear blight disease [10,14,19]. It is essential to identify the mechanisms of tolerance and introduce associated trait/s into new cultivars
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