Breeding-assisted genomics: Applying meta-GWAS for milling and baking quality in CIMMYT wheat breeding program.

One of the biggest challenges for genetic studies on natural or unstructured populations is the unbalanced datasets where individuals are measured at different times and environments. This problem is also common in crop and animal breeding where many individuals are only evaluated for a single year and large but unbalanced datasets can be generated over multiple years. Many wheat breeding programs have focused on increasing bread wheat (Triticum aestivum L.) yield, but processing and end-use quality are critical components when considering its use in feeding the rising population of the next century. The challenges with end-use quality trait improvements are high cost and seed amounts for testing, the latter making selection in early breeding populations impossible. Here we describe a novel approach to identify marker-trait associations within a breeding program using a meta-genome wide association study (GWAS), which combines GWAS analysis from multi-year unbalanced breeding nurseries, in a manner reflecting meta-GWAS in humans. This method facilitated mapping of processing and end-use quality phenotypes from advanced breeding lines (n = 4,095) of the CIMMYT bread wheat breeding program from 2009 to 2014. Using the meta-GWAS we identified marker-trait associations, allele effects, candidate genes, and can select using markers generated in this process. Finally, the scope of this approach can be broadly applied in 'breeding-assisted genomics' across many crops to greatly increase our functional understanding of plant genomes.

Alterations in muscular oxidative metabolism parameters in incremental treadmill exercise test in untrained rats.

The present study investigates the effects of incremental exercise test on muscular oxidative metabolism. Thirty-six 2-month-old male Wistar rats were distributed in seven groups that performed exercise at different levels: first level (control), second level (0.6 km/h), third level (0.6 and 0.8 km/h), fourth level (0.6, 0.8 and 1.0 km/h), fifth level (0.6, 0.8, 1.0 and 1.2 km/h), sixth level (0.6, 0.8, 1.0, 1.2 and 1.4 km/h), and seventh level (0.6, 0.8, 1.0, 1.2, 1.4 and 1.6 km/h). At the end of the exercise challenge, level of blood lactate (BL), glycogen content (MG), creatine kinase (CK), complexes (CI, CII, CIII, CIV), oxidative damage, succinate dehydrogenase (SDH), cytochrome c oxidase as well as antioxidant enzymes (SOD and CAT) expression were measured. The speed of 1.0 km/h increased BL level, while 1.2 km/h decreased MG and increased serum CK. Increased SDH expression was observed after intensity levels 6 and 7, and cytochrome c oxidase expression increased after levels 5, 6 and 7, in comparison with lower intensity levels, ETC enzyme activities increased when exercise was applied at intensities of 0.8 km/h (CI), 1.0 km/h (CII and CIII), and 1.2 km/h (CIV). The increase in SOD expression did not occur as observed for superoxide production, except for rats that underwent exercise at level 7, but CAT expression increased significantly in all levels, starting from level 3. Our results show interesting alterations in the muscular metabolism parameters, and suggest a differential response of muscle oxidative metabolism when intense exercise is applied at different speeds.