Association mapping and candidate gene identification for yield traits in European hazelnut (Corylus avellana L.).

European hazelnut (Corylus avellana L.) is an important nut crop due to its nutritional benefits, culinary uses, and economic value. Türkiye is the leading producer of hazelnut, followed by Italy and the United States. Quantitative trait locus studies offer promising opportunities for breeders and geneticists to identify genomic regions controlling desirable traits in hazelnut. A genome-wide association analysis was conducted with 5,567 single nucleotide polymorphisms on a Turkish core set of 86 hazelnut accessions, revealing 189 quantitative trait nucleotides (QTNs) associated with 22 of 31 traits (p < 2.9E-07). These QTNs were associated with plant and leaf, phenological, reproductive, nut, and kernel traits. Based on the close physical distance of QTNs associated with the same trait, we identified 23 quantitative trait loci. Furthermore, we identified 23 loci of multiple QTs comprising chromosome locations associated with more than one trait at the same position or in close proximity. A total of 159 candidate genes were identified for 189 QTNs, with 122 of them containing significant conserved protein domains. Some candidate matches to known proteins/domains were highly significant, suggesting that they have similar functions as their matches. This comprehensive study provides valuable insights for the development of breeding strategies and the improvement of hazelnut and enhances the understanding of the genetic architecture of complex traits by proposing candidate genes and potential functions.

Association analysis of germination level cold stress tolerance and candidate gene identification in Upland cotton (Gossypium hirsutum L.).

Cotton originated from ancestors in the Gossypium genus that grew in semi-desert habitats. As a result, it is adversely affected by low temperatures especially during germination and the first weeks of growth. Despite this, there are relatively few molecular studies on cold stress in cotton. This limitation may present a future breeding handicap, as recent years have witnessed increased low temperature damage to cotton production. Cold tolerance is a sustainable approach to obtain good production in case of extreme cold. In the present study, 110 Upland cotton (Gossypium hirsutum) genotypes were evaluated for cold tolerance at the germination stage. We identified vigorous genotypes with cold-related parameters that outperformed the panel's average performance ( x ¯ = 76.9% CG, 83.9% CSI, 167.5 CWVI). Molecular genetic diversity analysis with 101 simple sequence repeat (SSR) markers yielding 416 loci was used to select tolerant genotypes that could be important materials for breeding this trait. A total of 16 marker-cold tolerance trait associations (p < 0.005) were identified with 10 of them having major effects (PVE > 10%). Based on the positions of these markers, candidate genes for cold tolerance in the G. hirsutum genome were identified. Three of these markers (BNL0569, CIR081 and CIR202) are important candidates for use in marker-assisted breeding for cold tolerance because they mapped to genes previously associated with cold tolerance in other plant species such as Arabidopsis thaliana, rice and tomato. Supplementary Information: The online version contains supplementary material available at 10.1007/s12298-022-01184-6.