Races belonging to the Ug99 (TTKSK) lineage of the wheat stem rust fungus, carrying complex virulence combinations, and their migration to countries in Africa, Middle East and Asia continue to pose a significant threat to global wheat production. The rapid spread of additional races, e.g., TKTTF or the Digalu lineage, in several countries causing localized epidemics reminds us of the vulnerability of wheat germplasm to stem rust disease, a formidable foe referenced as early as biblical times. A global rust monitoring system reflecting increased surveillance efforts has identified 13 races within the Ug99 lineage in 13 countries and unrelated lineages are emerging, spreading and posing serious threats to wheat production. Race TKTTF has caused localized epidemics in Ethiopia and its variants have been recently implicated in stem rust outbreaks in Europe. Concerted research efforts have resulted in the identification of several new resistance (APR) genes and gene combinations for use in breeding. Combining multiple adult plant resistance genes in high-yielding backgrounds and discovery of new quantitative trait loci conferring stem rust resistance has progressed in the recent years, enhancing the durability of resistance. Effective gene stewardship and new generation breeding materials and cultivars that combine multiple race-specific or minor to intermediate effect APR genes, complemented by active surveillance and monitoring, have helped to limit major epidemics and increase grain yield potential in key target environments.
The application of spectral reflectance indices (SRIs) as proxies to screen for yield potential (YP) and heat stress (HS) is emerging in crop breeding programs. Thus, a comparison of SRIs and their associations with grain yield (GY) under YP and HS conditions is important. In this study, we assessed the usefulness of 27 SRIs for indirect selection for agronomic traits by evaluating an elite spring wheat association mapping initiative (WAMI) population comprising 287 elite lines under YP and HS conditions. Genetic and phenotypic analysis identified 11 and 9 SRIs in different developmental stages as efficient indirect selection indices for yield in YP and HS conditions, respectively. We identified enhanced vegetation index (EVI) as the common SRI associated with GY under YP at booting, heading and late heading stages, whereas photochemical reflectance index (PRI) and normalized difference vegetation index (NDVI) were the common SRIs under booting and heading stages in HS. Genome-wide association study (GWAS) using 18704 single nucleotide polymorphisms (SNPs) from Illumina iSelect 90K identified 280 and 43 marker-trait associations for efficient SRIs at different developmental stages under YP and HS, respectively. Common genomic regions for multiple SRIs were identified in 14 regions in 9 chromosomes: 1B (60–62 cM), 3A (15, 85–90, 101–105 cM), 3B (132–134 cM), 4A (47–51 cM), 4B (71–75 cM), 5A (43–49, 56–60, 89–93 cM), 5B (124–125 cM), 6A (80–85 cM), and 6B (57–59, 71 cM). Among them, SNPs in chromosome 5A (89–93 cM) and 6A (80–85 cM) were co-located for yield and yield related traits. Overall, this study highlights the utility of SRIs as proxies for GY under YP and HS. High heritability estimates and identification of marker-trait associations indicate that SRIs are useful tools for understanding the genetic basis of agronomic and physiological traits.
Penthorum chinense Pursh (PCP) is a popular traditional medicinal plant in China, widely used for the treatment of a variety of liver diseases. Although it has been long recognized that the main active elements of PCP are contained in ethyl acetate fraction (EAF), little is known so far in terms of the relative effectiveness of EAF derived from the stems versus leaves of this plant. In the current study, we prepared EAF by reflux extraction and sequential extraction from the stems (SEAF) and leaves (LEAF) of PCP and tested their hepatoprotective efficacies. The extract rates and flavonoid contents of LEAF were higher than those of SEAF. EAFs (>50 μg·mL−1) prevented lipid accumulation in cells and protected against lipotoxicity injury when the concentration exceeded 25 μg·mL−1. More than 95% free radicals released by 2,2-diphenyl-1-picrylhydrazyl (DPPH) were eliminated by 25 μg·mL−1 SEAF and 50 μg·mL−1 LEAF, respectively. Further, EAFs (25 μg·mL−1) also showed protective antioxidant effects, with the activity of LEAF being significantly higher than that of SEAF. EAFs (10 mg·mL−1) also showed similar unspecific bacteriostatic activity. In comparison with SEAF, LEAF contained more flavonoids and had a higher anti-oxidation capability and for these reasons we suggest it should be better for clinical use.
Before the advent of the wheat genomic era, a wide range of studies were conducted to understand the chemistry and functions of the wheat storage proteins, which are the major determinants of wheat flour the suitability of wheat flour for various end products, such as bread, noodles and cakes. Wheat grain protein is divided into gluten and non-gluten fractions and the wheat processing quality mainly depends on the gluten fractions. Gluten provides the unique extensibility and elasticity of dough that are essential for various wheat end products. Disulfide bonds are formed between cysteine residues, which is the chemical bases for the physical properties of dough. Based on the SDS-extractability, grain protein is divided into SDS-unextractable polymeric protein (UPP) and SDS-extractable polymeric protein. The percentage of UPP is positively related to the formation of disulfide bonds in the dough matrix. In the wheat genomic era, new glutenins with long repetitive central domains that contain a high number of consensus hexapeptide and nonapeptide motifs as well as high content of cysteine and glutamine residues should be targeted.
The publications of the International Wheat Genome Sequencing Consortium (IWGSC) released in August 2018 are reviewed and placed into the context of developments arising from the availability of the high-quality wheat genome assembly.
Wheat is one of the most important crops in both China and the world, and its domestication can be traced back to ~10000 years ago. However, the history of its origin and utilization in China remains highly ambiguous. Drawing upon the most recent results of taxonomic, genetic, archeological and textual studies focused on the wheat in prehistory, this paper argues that wheat was not domesticated but introduced into China in the late fifth millennium BP. In the subsequent centuries, this exotic crop was quickly utilized as a staple food in northwest China. In contrast, it was not adopted as a staple in Central Plains until the Han Dynasty (202 BCE–220 CE), which was mainly as a consequence of the living environment, population and innovations in food processing technology.
International Winter Wheat Improvement Program (IWWIP) was established in 1986 between the Government of Turkey and CIMMYT with three main objectives: (1) develop winter/facultative germplasm for Central and West Asia, (2) facilitate global winter wheat germplasm exchange, and (3) training wheat scientists. ICARDA joined the program in 1991 making it a three-way partnership that continues to work effectively. The germplasm developed by IWWIP as well as the winter wheat cultivars and lines received from global cooperators are assembled into international nurseries. These nurseries are offered annually to public and private entities (IWWIP website) and distributed to more than 100 cooperators in all continents. IWWIP impact has primarily been in new winter wheat cultivars combining broad adaptation, high yield potential, drought tolerance and disease resistance. A total of 93 IWWIP cultivars have been released in 11 countries occupying annually an estimated 2.5–3.0 Mha. IWWIP cooperation with researchers in Turkey, Central and West Asia and several US universities has resulted in a number of publications reviewed in this paper. Important IWWIP impacts include national inventories of wheat landraces in Turkey, Tajikistan and Uzbekistan, their collection, characterization, evaluation and utilization.
With the changes of climate and cultivation systems, the Fusarium head blight (FHB) epidemic area in China has extended since 2000 from the reaches of the Yangtze River to the north and west winter wheat region. Breeding for FHB resistance in wheat is an effective way to control the disease. Chinese wheat breeders commenced research on FHB in the 1950s. Sumai 3, Ning 7840, Yangmai 158, Ningmai 9 and other cultivars with improved FHB resistance were developed through standard breeding methods and widely applied in production or breeding programs. In addition to intervarietal crosses, alien germplasm was used to improve FHB resistance of wheat. Addition, substitution and translocation lines with alien chromosomes or chromosome fragments were created to enhance FHB resistance. Somaclonal variation was also used to develop a FHB resistant cv. Shengxuan 3 and other cultivars with moderate resistance to FHB were released by such methods. QTL (quantitative trait loci) for FHB resistance were characterized in cultivars originating from China. The major QTL, Fhb1, was identified on chromosome 3BS in Sumai 3, Ning 894037, Wangshuibai and other Chinese resistant sources. Diagnostic molecular markers for Fhb1 have been applied in wheat breeding and breeding lines with improved FHB resistance and desirable agronomic traits have been obtained. However, breeding for FHB resistance is a long-term task, new technologies are likely to increase the efficiency of this process and better FHB resistance of new cultivars is expected to be achieved within the next decade.