Genetic control of seed dormancy and pre-harvest sprouting in wheat

Abstract

Pre-harvest sprouting (PHS) damage leads to occasional massive losses in all wheat producing areas, causing downgrading of grain quality, that severely limits end-use applications and results in substantial financial losses to farmers and food processors. Red grain color is a traditional marker for resistance to sprouting in wheat breeding programs, however red-grained genotype alone does not always guarantee effective resistance. The objective of this work was to find genes for resistance to PHS and investigate its inheritance in Brazilian wheat cultivars. Genetic variation for dormancy was investigated in the parents, F 1 and 300 F 2 lines derived from the cross Frontana × OR1 and its reciprocal. The germination/ dormancy sprouted grains was evaluated on fifty seeds per replication, germinated in paper towel rolls at 20°C for 5 days. A bimodal distribution for dormancy occurred in the Frontana/OR1 and OR1/Frontana derived F 2 populations. The mean ratio of dormant and non-dormant seeds of the cross and its reciprocal was 85:1115, fitting a digenic model of 1:15 (P < 0.05). In fact, all non after-ripened F 1 seeds germinated. The F 2 distribution indicates that two major genes, here called A,a and B,b, control seed dormancy, which it appears to be recessive to dormancy. Only the homozygous aabb is dormant. As expected, there was no effect of maternal tissues.

Tolerance to preharvest sprouting and yield of wheat genotypes from different breeding programs

“…The strong GxE interaction for yield components, such as NFT, WTG, and NGE, indicate that more than one year of evaluation is needed for an effective characterization of performance in wheat genotypes (Valério et al, 2013). The strong environmental action on the dormancy and germination of wheat genotypes has been described, suggesting a quantitative inheritance (Bassoi et al, 2006). However, it is difficult to identify steady genotypes for PHS-related traits when different growing conditions are compared (Rasul et al, 2012).…”

“…The higher germination values indicate that seeds have lower accumulated dormancy, characterizing an advanced germination process (Bassoi et al, 2006;Gelin et al, 2007). For both experimental years, the TBIO Alvorada, Fundacep Horizonte, Fundacep Campo Real, and BRS 194 genotypes were superior, presenting lower values for GG (Table 2).…”

“…The Frontana genotype, which is internationally recognized as a standard for tolerance to PHS, was fit when FN was analyzed. Some reports have shown low germination potential for the cultivar Frontana (Andreoli et al, 2006;Bassoi et al, 2006), reassuring its use as a control for tolerance to PHS. It is important to highlight that, although in 2011 the numbers of phenotypic classes for FN were similar among the PHS detecting variables (Table 2), twice as many phenotypic classes were obtained in 2010, facilitating the analysis of genetic variability for PHS expression.…”

“…The study of wheat populations indicated the presence of tolerant genotypes and the potential for obtaining genetic gains (Bassoi et al, 2006); however, few traits associated with tolerance to PHS have been reported. Though visual scoring (grain germination) can be relatively efficient, laboratory methods, such as FN, have shown to be more reliable in detecting the activity of enzymes linked to germination, even when seeds are not visibly germinated (Gelin et al, 2007).…”

“…2015 DOI: 10.1590/S0100-204X2015000800008 (Emebiri et al, 2010;Martynov & Dobrotvorskaya, 2012;Zhang et al, 2014). However, selection of plants with tolerance to PHS is difficult, due to its quantitative inheritance (Fofana et al, 2009) and strong environmental influence (Bassoi et al, 2006). One of the main methods for evaluating PHS is the conventional test that simulates field conditions, in which spikes are immersed in water and kept wet for a certain period to allow the germination of sensitive genotypes.…”