Grain and flour quality of wheat genotypes grown under heat stress.

Heat stress during the grain-filling period is the main abiotic stress factor limiting grain yield and quality in wheat (Triticum aestivum L.). In this study, 64 wheat genotypes were exposed to heat stress during reproduction caused by delayed sowing in two growing seasons. Grain yield, 1000 grain weight (GW), grain hardness (GH), and grain-quality related traits were investigated. Heat stress caused a significant decrease in GW through reducing starch content (SC) and a non-compensating rise in protein content (PC), and thereby resulted in lower yield. In addition, significant increases in flour water absorption (WA), Zeleny sedimentation volume (ZT), ash content (AC), lipid content (LC), loaf volume (LV), wet gluten content (WG), dry gluten content (DG), gluten index (GI), and amylopectin content (APC) were found following heat stress. In contrast, decreases in grain moisture content (MC) and amylose content (AMC) induced by heat stress were observed. The heat-tolerant genotypes were superior in grain yield, GW, SC, AMC, and MC. While the sensitive genotypes contained higher PC, LV, GI and AMP. A group of wheat genotypes characterized with a higher yield, AMC, GW, and SC as well as lower PC, WA, GH, ZT, and LV; and was found to be the most heat tolerant by principal component analysis. Lighter weight and smaller grains produce a smaller starchy endosperm with lower quality (less amylose) and higher grain protein content in heat stress compared to normal conditions. Heat stress caused by delayed sowing improves some of the baking-quality related traits.

Inbred progeny of tall fescue infected with Epichloë fungal endophyte have a high defence compound content and no depression in seed set.

Substantial evidence is available on the capacity of particular strains of Epichloë fungal endophyte to remove the barriers of self-pollination in host grasses. We hypothesized that this might open up new methods to obtain inbred lines for specific turf hybrids and genetic studies. In the present study, we evaluated the first generation of self-pollination derived plants of endophyte infected clones (EIS1 ) from putative genotypes 75B+ and 75C+ and those from the first generation of self-pollination in six commercial tall fescue clones plus their hybrids with 75B- and 75C- for growth, seed yield and polyphenolic content as an index for biosynthesis of defence compounds under field conditions. The results showed that EIS1 had high hyphal density within leaf sheaths and higher growth and seed-related traits in at least one genotype. There were higher amounts of flavonoid and phenolic compounds (up to twofold) in both genotypes than in their hybrid counterparts and endophyte-free progeny. Selected genotypes within EIS1 contained significantly more chlorogenic acid, p-coumaric acid and rutin than the best non-infected genotypes. We conclude that phenotypic selection of individuals from the S1 population is feasible for improving fitness and stress resistance in novel inbred lines of tall fescue for development of new turf cultivars with the desired ecophysiological traits.

Polyphenols, Flavonoids, and Antioxidant Activity Involved in Salt Tolerance in Wheat, Aegilops cylindrica and Their Amphidiploids.

Aegilops spp. is the closest genus to wheat (Triticum spp.), which makes Aegilops great candidates to exhibit precursors of wheat features. Aegilops cylindrica Host displays excellent salt tolerance. In the current study, biochemical and phytochemical compounds in the leaves of two wheat cultivars, one hyper-salt tolerant Ae. cylindrica genotype and their amphidiploids (derived from "Chinese Spring" × Ae. cilindrica and "Roshan" × Ae. cylindrica), grown under control and saline field conditions, were assessed. These compounds included total protein content, proline content, electrolyte leakage, total flavonoid content, total phenolic content, DPPH radical scavenging activity, and reducing power. In addition, phenolic components were also identified using HPLC analysis. Chlorogenic acid, ellagic acid, ferulic acid, syringic acid, vanillic acid, p-coumaric acid, caffeic acid, and gallic acid were the most abundant phenolic acids. Luteolin, apigenin, and rutin were the most abundant flavonoids in the leaves. Salt stress significantly increased all biochemical variables, with the exceptions of reducing power and p-coumaric acid. Interestingly, amphidiploid genotypes exhibited intermediate levels of most of the detected phenolic compounds between the two parental species. As demonstrated by bivariate correlations luteolin, chlorogenic acid, caffeic acid and apigenin could predict inhibition percentage by DPPH assay, suggesting a possible role in the cellular defense against oxidative stress in wheat. The amphidiploids and their wild parent performed significantly better than wheat cultivars on phenolic constituents, flavonoids, and maintaining redox homeostasis under salt stress conditions.