Quantitative Trait Loci and Candidate Genes Associated with Cold-Acclimation and Microdochium nivale Tolerance/Susceptibility in Winter Triticale (x Triticosecale)

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.

The Genome Regions Associated with Abiotic and Biotic Stress Tolerance, as Well as Other Important Breeding Traits in Triticale

“…As mentioned, genetic maps can be used in positioning quantitative trait loci (QTL) that are linked with multiple traits. Up to now, many research studies have described the QTL regions associated with triticale resistance to both biotic and abiotic stresses such as resistance to Fusarium head blight (FHB) [ 17 , 24 , 25 , 26 ], powdery mildew [ 16 , 22 , 27 , 28 ], yellow rust [ 11 , 17 , 29 ], pink snow mold [ 30 , 31 , 32 ], drought [ 33 , 34 , 35 ], and freezing [ 23 , 32 ]. Many studies showed the analysis of QTL regions associated with the important agronomic factors and morphological features of triticale [ 36 , 37 , 38 , 39 , 40 ].…”

“…Such genes that encode multiple proteins can be widely used in modern molecular breeding programs, but so far, not many studies have described such genes identified in crops. In triticale, the information of important candidate genes is still limited [ 16 , 22 , 23 , 28 , 32 , 45 ].…”

“…As has been shown by many years of research, low temperature may increase the triticale tolerance to stresses that coexist with cold in winter, which could remain persistent during the following early spring period and even at the plant adult stage. Tolerance to freezing [ 23 ] and pink snow mold caused by Microdochium nivale [ 32 ] appears after a cold-hardening period and it is an essential, genotype-dependent, complex quantitative trait for wintering.…”

“…Long-term studies indicate that after long-term exposure to low temperature (acclimation, hardening), cereal seedlings acquire genotype-dependent cross-tolerance to other later stresses. Low temperature (4 weeks at 4 °C) may increase the tolerance of triticale seedlings to stresses coexisting with cold in winter, which may persistently follow throughout the early spring period and even in the adult phase of the plant [ 16 , 23 , 28 , 32 , 51 , 52 ]. Tolerance to pink snow mold caused by M. nivale appears after a period of hardening with low temperature and is a genotype-dependent, complex feature significant for wintering seedlings [ 23 , 31 , 32 , 52 , 53 ].…”

Resistance to Snow Mold as a Target Trait for Rye Breeding

“…In Krasnodar territory (south of Russia with little or no snow), M. nivale -caused SM exceeds the epiphytotic level 3–5 times per 10 years, causing yield losses of up to 20% [ 30 ]. In addition, M. nivale has been shown to cause not only SM but also other diseases on cereal crops in the southern parts of Russia [ 23 , 31 ], Poland [ 32 , 33 , 34 ], Denmark [ 35 ], Japan [ 36 ], and China [ 37 ] throughout the growing season.…”