How do eyespot resistance genes transferred into winter wheat breeding lines affect their yield?

Abstract

Eyespot can reduce yields, even up to 50%. There are four genetically characterized resistances in wheat varieties, controlled by: (1) the Pch1 gene, transferred from Aegilops ventricosa; (2) the Pch2 gene, originating from wheat variety Capelle Desprez; (3) the Q.Pch.jic-5A genes was compared with resistance conferred by Pch1 or Q.Pch.jic-5A alone. We found significant differences between infection scores evaluated in resistant lines carrying Pch1 and Q.Pch.jic-5A alone, while no differences in terms of the level of resistance expression were detected between Pch1 alone and Pch1 + Q.Pch.jic-5A, and between wheat lines carrying Pch1 and Pch2 alone. Moreover, we demonstrated that the Pch1 gene, together with an Ae. ventricosa segment, caused statistically significant yield losses, both as a single eyespot resistance source or in a combination with Q.Pch.jic-5A. Yield scores showed that wheat lines with Q.Pch.jic-5A had the highest yields, similar to the yielding potential of Pch2-bearing lines and control varieties.

Chromosomal distribution of pTa-535, pTa-86, pTa-713, 35S rDNA repetitive sequences in interspecific hexaploid hybrids of common wheat (Triticum aestivum L.) and spelt (Triticum spelta L.)

“…Polymorphic sites were observed in 1B and 6B chromosomes ( Fig 4 ). Our findings are consistent with the previous study [ 40 ]- the telomeric region of the short arm of chromosome 6B is polymorphic, probably due to evolutionary changes. The pTa-713 probe was highly helpful in identifying chromosome 5B.…”

Yield reduction historically associated with the Aegilops ventricosa 7DV introgression is genetically and physically distinct from the eyespot resistance gene Pch1

“…The relationship between the negative yield effect and Pch1 has long been uncertain, but early reports suggested that the addition of the entire 7D V chromosome could reduce yields by approximately 8% (Worland et al 1990). Some studies have concluded that the presence of Pch1 is responsible for any negative impact on yield (Kwiatek et al 2016), while other studies noted that an effect only occurred in some instances (Koen et al 2002). In an early study using the same population as used in the current work, but lacking a detailed genetic map, a negative impact on yield was associated with the Pch1 locus on both drilled and spaced planting plot trials while a second, more pronounced effect was identified nearer the centromere only in the drilled plot trial (Worland et al 1990).…”

“…For example, Koen et al (2002) found that the presence of the Pch1 introgression segment had a detrimental effect on thousand-kernel weight in two near isogenic lines (8.5-9.25% lower than the SST66 parental line) and on yield in one line (40% less than the Palmiet parental line), but no detrimental effects on quality were detected. Kwiatek et al (2016) also demonstrated that the presence of Pch1 containing Ae. ventricosa segment caused statistically significant yield losses, both as a single eyespot resistance source or in a combination with a second eyespot resistance (Q.Pch.jic-5A), corresponding, respectively, to 10.38% and 10.51% in comparison with non-resistant control wheat varieties.…”

“…Moreover, dough stickiness is present in wheat lines containing the 1BL-1RS wheat-rye (Secale cereale) chromosome translocation originally introduced to enhance rust resistance through the action of Yr9, Lr26 and Sr31 (Dhaliwal et al 1987;Hsam et al 2000). Another introgressed gene which has been reported to have a pleiotropic negative effect is the eyespot resistance gene Pch1 (Kwiatek et al 2016).…”

“…However, in northern Europe, the perception that the presence of the Pch1 Ae. ventricosa segment has an adverse effect on yield has limited uptake of this resistance (Kwiatek et al 2016). For example, it is only recently that Pch1 carrying varieties have been developed with sufficiently high yield potential to succeed in being placed on the Agriculture and Horticulture Development Board's Recommended List for cereals in the UK.…”