Genetic variation of bioavailable iron and zinc in grain of a maize population

More than one-third of the world's population is afflicted by iron (Fe) and zinc (Zn) deficiencies, since cereal grain as a staple food of the people contains low levels or low bioavailability of Fe and Zn because of phytate. In maize, 80% of grain phosphorus (P) is in the form of phytate, and P could be an indicator of phytate content. The objectives of this study were (1) to estimate genetic variation of Fe and Zn in a maize population including P/Fe and P/Zn molar ratios as quantitative traits; (2) to determine relations among yield, P, Fe, Zn, P/Fe and P/Zn molar ratios; and (3) to define the implications of those on biofortification (breeding) programmes. There were significant genetic variations and workable heritabilities for Fe, Zn, P/Fe and P/Zn estimated in 294 F4 lines of a maize population, but there were no associations among six traits according to both simple correlations and principal component analysis. Weak correlations between P and Fe and between P and Zn indicated feasibility of breeding non low-phytic acid maize genotypes with more appropriate phytate/Fe and phytate/Zn relations. Bioavailability of iron and zinc varied substantially in a maize population justifying utilisation of these unique parameters in biofortification programmes.     

Genotype by environment interactions in wheat quality breeding programs in southeast Europe

The objective of this study was to determine genotype × environment interactions (GEI) obtained in wheat production in southeast Europe for protein content, sedimentation value, and loaf volume. Twenty wheat genotypes divided in two groups with different combinations of high molecular weight glutenin subunits (HMW-GS) were analyzed in 15 environments (E). In a combined analysis of variance, effects of genotype, environment, and their interaction (GEI) were highly significant for almost all the analyzed traits. All the three traits were influenced more by location than by year, with protein content and sedimentation value being more responsive to changes in environmental conditions than loaf volume. The genotypes with high protein content had the regression coefficient value (b) close to 1, indicating that they did not react to extreme environmental conditions as was the case with genotypes with high sedimentation and loaf volume values. There were no significant differences in average values for the analyzed traits and adaptability parameters between the two groups of genotypes. It means that, concerning wheat quality improvement, genotypes with different HMW-GSs on the Glu-1D locus could be recommended for growing in southeast Europe. It is necessary to take into account the differences in adaptability of protein content to either positive or negative environmental changes that were observed between the groups.     

Antagonists induce a conformational change in cIAP1 that promotes autoubiquitination

Inhibitor of apoptosis (IAP) proteins are negative regulators of cell death. IAP family members contain RING domains that impart E3 ubiquitin ligase activity. Binding of endogenous or small-molecule antagonists to select baculovirus IAP repeat (BIR) domains within cellular IAP (cIAP) proteins promotes autoubiquitination and proteasomal degradation and so releases inhibition of apoptosis mediated by cIAP. Although the molecular details of antagonist-BIR domain interactions are well understood, it is not clear how this binding event influences the activity of the RING domain. Here biochemical and structural studies reveal that the unliganded, multidomain cIAP1 sequesters the RING domain within a compact, monomeric structure that prevents RING dimerization. Antagonist binding induces conformational rearrangements that enable RING dimerization and formation of the active E3 ligase.