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Rht24 is a major dwarfing allele that not only reduces plant height but also increases grain weight. The objective of this study was to trace the source, spread, and distribution of Rht24 and determine its frequency in conjunction with other important dwarfing alleles for Rht1 (Rht-B1b), Rht2 (Rht-D1b), and Rht8. Allele-specific cleaved amplified polymorphic sequence (CAPS) markers were developed for accurate and effective genotyping of Rht1 and Rht2, and closely linked flanking markers were used for genotyping of Rht8 and Rht24. Marker analysis showed that Rht24 occurs at a higher frequency (84.2%) than other important dwarfing alleles in elite wheat (Triticum aestivum L.) varieties and usually couples with Rht2 or Rht8. Geno- typing of old varieties and landraces showed that Rht24 was widely used in wheat breeding before the Green Revolution (GR). 'Akakomugi' and 'Norin 10', the donors of Rht8 and GR genes Rht1 and Rht2, respectively, harbored Rht24, so Rht24 likely followed the transfer routes of GR genes and Rht8 to spread worldwide. Pedigree analysis showed that many Chinese elite lines and backbone parents were derived from Akakomugi, contributing to the high frequency of Rht24 in Chinese varieties. Additionally, Norin 10-derived semidwarf varieties from the CIMMYT were widely used in Chinese wheat breeding. Finally, Rht24 was also detected in 30 old Chinese varieties and landraces. Overall, these findings show that the presence of Rht24 in modern Chinese elite varieties originated from Akakomugi, Norin 10, or Chinese landraces. Thus, Rht24 was introgressed early, spread widely, and became genetically fixed in a wide range of modern Chinese wheat germplasm. [ABSTRACT FROM AUTHOR]

Understanding the key characteristics associated with genetic gains achieved through breeding is essential for improving yield-limiting factors and designing future breeding strategies in bread wheat (Triticum aestivum L.) cultivars. The objective of the present study was to investigate the genetic progress in yield-related and physiological traits in cultivars released from 1950 to 2012 for irrigated conditions in the southern Yellow and Huai Valleys Winter Wheat Zone. Field trials including 26 leading cultivars from 1950 to the present time were conducted at Zhengzhou and Zhoukou in Henan Province, during the 2013-2014 and 2014-2015 cropping seasons, providing data from four environments. Grain yield (GY) was significantly increased by the linear rate of 57.5 kg ha-1 yr-1 or 0.70% (R2 = 0.66, P < 0.01) and significantly correlated with increased thousandkernel weight (TKW) (r = 0.48, P < 0.05), spike number m-2 (r = 0.44, P < 0.05), kernels m-2 (r = 0.56, P < 0.01), aboveground biomass (AGBM) (r = 0.80, P < 0.01), harvest index (HI) (r = 0.84, P < 0.01), watersoluble carbohydrate at 10 d postanthesis (WSC-10) (r = 0.80, P < 0.01), and reduced plant height (PH) (r = -0.85, P < 0.01). There was no significant change in kernel number per spike, heading date, normalized difference in vegetation index at anthesis and at 10 d postanthesis, leaf area index at anthesis and at 10 d postanthesis, and canopy temperature depression at anthesis during the past 60 yr. Soil plant analysis development (SPAD) estimates of chlorophyll content at 10 d postanthesis (Chl-10) increased with year of release and were significantly correlated with GY (r = 0.69, P < 0.01), PH (r = -0.76, P < 0.01), AGBM (r = 0.52, P < 0.01), HI (r = 0.71, P < 0.01), and WSC-10 (r = 0.73, P < 0.01). Cultivars conferring Rht-D1b and Rht- D1b + Rht8c showed increased GY, TKW, AGBM, HI, WSC-10, and Chl-10. Stem water solubility content can be used as a selection criterion for further improving yield potential. [ABSTRACT FROM AUTHOR]

Leaf rust and powdery mildew, caused by Puccinia triticina and Blumeria graminis f. sp. tritici, respectively, are widespread fungal diseases of wheat (Triticum aestivum L.). Development of cultivars with durable resistance is crucially important for global wheat production. This paper reviews the progress of genetic study and application of adult plant resistance (APR) to wheat leaf rust and powdery mildew. Eighty leaf rust and 119 powdery mildew APR quantitative trait loci (QTL) have been reported on 16 and 21 chromosomes, respectively, in over 50 publications during the last 15 yr. More important, we found 11 loci located on chromosomes 1BS, 1BL, 2AL, 2BS (2), 2DL, 4DL, 5BL, 6AL, 7BL, and 7DS showing pleiotropic effects on resistance to leaf rust, stripe rust, and powdery mildew. Among these, QTL on chromosomes 1BL, 4DL, and 7DS also correlate with leaf tip necrosis. Fine mapping and cloning of these QTL will be achieved with the advent of cheaper high-throughput genotyping technologies. Germplasm carrying these potential resistance genes will be useful for developing cultivars with durable multidisease resistance. In addition to its non-NBS-LRR (nucleotide binding site-leucine rich repeat) structure, the senescence-like processes induced by Lr34 could be the reason for durability of resistance; however, more information is needed for a full understanding of the molecular mechanism related to durability. Adult plant resistance genes have been used by CIMMYT for more than 30 yr and have also been transferred to many Chinese wheat varieties through shuttle breeding. [ABSTRACT FROM AUTHOR]

The puroindoline genes (Puroindoline a-D1 and Puroindoline b-D1), located very near to the distal end of the short arm of chromosome 5D (distal to fraction arm length of 0.78) have a significant effect on grain hardness. Puroindoline b-2 (Pinb-2) is another puroindoline gene family that exists as a homoeologous series on group 7 chromosomes. However, a more detailed localization (physical mapping) of the Pinb-2 genes has not been conducted. In the present study, 24 group 7 long-arm chromosome deletion stocks of 'Chinese Spring' were used to physically map three Pinb-2 variant genes: Pinb-2v1, Pinb-2v2, and Pinb-2v4. All three genes were found to be physically located on the most distal 0.11 to 0.16 fraction arm length of chromosomes 7AL, 7BL, and 7DL in Chinese Spring. These results contribute insight into wheat (Triticum aestivum L.) genome synteny, structure, and organization and provide a useful metric for germplasm and population relationships. Future studies may further resolve the physical mapping of Pinb-2 genes at the ends of group 7 chromosomes and contribute to a better understanding of the molecular and genetic basis of kernel hardness. [ABSTRACT FROM AUTHOR]

Lipoxygenase (LOX) activity in grain influences the color and processing quality of wheat (Triticum spp.)-based products. Characterization of LOX genes and development of functional markers are of importance for marker-assisted selection in common wheat (Triticum aestivum L.) breeding. In the present study, the full-length genomic DNA (gDNA) sequence of a LOX gene (designated TaLox-B1) located on chromosome 4BS was characterized by in silico cloning and experimental validation. Two complementary dominant sequence tagged site (STS) markers, LOX16 and LOX18, were developed based on the single nucleotide polymorphism (SNP) of two alleles at the TaLox-B1 locus, amplifying 489- and 791-bp fragments in cultivars with higher and lower LOX activities, respectively. The two markers were mapped on chromosome 4BS using a doubled haploid (DH) population derived from Zhongyou 9507 × CA9632, a set of Chinese Spring nullisomic-tetrasomic lines, ditelosomic line 4BS, and Langdon (LDN) 4D(4B) chromosome substitution line. Quantitative trait loci (QTL) analysis indicated that TaLox-B1 co-segregated with the two functional markers and was closely linked to simple sequence repeat (SSR) locus Xgwm251 on chromosome 4BS with a genetic distance of 1.8 cM. LOX16 and LOX18 were validated on 198 Chinese wheat cultivars and advanced lines and showed highly significant (p < 0.01) associations with LOX activity. These results suggested that LOX16 and LOX18, co-segregating with TaLox-B1, could be used for the improvement of color attributes of noodles and other wheat-based products in wheat breeding programs. [ABSTRACT FROM AUTHOR]

Zeta (ζ)-carotene desaturase (ZDS) is a key enzyme in the carotenoid biosynthetic pathway, which determines the yellow pigment (YP) content in wheat (Triticum aestivum L.) grains. In the present study, the full-length DNA sequence of a ZDS gene on wheat chromosome 2DL, designated TaZds-D1, was characterized. The TaZds-D1 gene has an open reading frame of 1707 bp, including 13 introns and 14 exons, and a deduced peptide containing 568 amino acid residues with a predicted molecular weight of 62.5 kDa. The TaZds-D1 gene was located on chromosome 2DL based on polymerase chain reaction amplifications of Chinese Spring nullisomic-tetrasomic lines, Langdon-Chinese Spring D-genome chromosome disomic substitution lines, and Rusty D-genome chromosome disomic substitution lines as well as linkage analysis. Two allelic variants, TaZds-D1a and TaZds-D1b, were detected in Chinese wheat cultivars, and a functional marker, YP2D-1, was developed based on the sequence polymorphism between TaZds-D1a and TaZds-D1b. A major quantitative trait locus, located at the TaZds-D1 region in the marker interval of YP2D-1 and Xgwm157 on chromosome 2DL, explained 18.4% of the phenotypic variance for YP content in a doubled haploid population derived from the cross Zhongyou 9507/CA 9632. This confirmed the association between allelic variation at the TaZds-D1 locus and YP content. [ABSTRACT FROM AUTHOR]

Phytoene synthase (PSY) genes are involved in the biosynthesis of carotenoid pigments in durum wheat [Triticum turgidum L. subsp. durum (Desf.) Husn.], significantly influencing grain yellowness. This study was conducted to identify new allelic variants at the Psy-A1 and Psy-B1 loci in durum wheat, and to evaluate the applicability of functional markers developed from common wheat (Triticum aestivum L.) for durum wheat breeding. Two new allelic variants, Psy-A1d and Psy-A1e, were identified at the Psy-A1 locus, and both the codominant markers YP7A and YP7A-2 can be used to discriminate the two haplotypes, yielding 194- and 231-bp polymerase chain reaction (PCR) products with YP7A and 1001- and 1684-bp fragments with YP7A-2, respectively. At the Psy-B1 locus, three allelic variants were identified. Psy-B1e was also found in common wheat, whereas Psy-B1f and Psy-B1g were detected only in durum wheat. The codominant marker YP7B-1 can be used to distinguish Psy-B1f and Psy-B1g, generating 151- and 153-bp PCR fragments, respectively, and the dominant marker YP7B-4 was specific to haplotype Psy-B1e, producing a 717-bp PCR product. In a set of 100 CIMMYT durum wheat lines with widely variable grain yellowness, the frequencies of Psy-A1d, Psy-A1e, Psy-B1e, Psy-B1f, and Psy-B1g were 99, 1, 0, 67, and 33%, respectively, and the genotype Psy-B1f showed a significant association with higher grain yellowness, whereas the presence of Psy-B1g led to lower yellowness. A phylogenetic tree generated from the gene sequences of the allelic variants at Psy-A1 and Psy-B1 loci indicated two parallel lineages of durum-common wheat, suggesting that more than one tetraploid T turgidum L. subsp. dicoccon (Schrank) Thell. genotypes were involved in the origin of common wheat. Our results suggested that Psy-B1f should be paid more attention in durum breeding programs for its association with elevated grain yellowness. [ABSTRACT FROM AUTHOR]

Objective To assess the influence of orphanhood due to AIDS on children’s nutritional status, psychological well-being and life quality, and to explore appropriate intervention strategies in China. Methods In 2005, 186 children aged 8–15 years (93 AIDS orphans and 93 non-orphans) from a rural area of Henan Province were surveyed in a cross-sectional and matched pairs study on nutritional status, psychological health and life quality. Results We found no compelling evidence for poorer nutritional status in orphans. The nutritional status of both orphans and non-orphans was extremely poor according to the prevalence of stunting, underweight, wasting and anaemia. Depression, low self-esteem and lower quality of life were more frequent in orphans. These differences mainly existed in boys’ groups. No significant differences were found between paternal, maternal and double orphans, or orphans in orphanages or extended families. Regression analysis revealed that orphanhood leads to low self-esteem and more depression which contributes to lower quality of life and mediates the association between orphanhood and quality of life. Conclusion The high prevalence of poor nutritional status indicates that basic material needs of children, including AIDS orphans, are not met in rural China. Psychological problems were prominent among orphans and had become the most important contributor of lower life quality. Boys were at least as vulnerable as girls. The living conditions of all children in rural China must be improved; school-based care and support are crucial and would be a cost-effective way to improve the overall life quality of AIDS orphans. [ABSTRACT FROM AUTHOR]

Development of soft wheat (Triticum aestivum L.) cultivars with excellent cookie quality is an important breeding objective in southern China. Seventeen Chinese soft wheat genotypes grown at three locations in the 2000-2001 and 2001-2002 seasons in the southern winter wheat region, were uniformly evaluated for their solvent retention capacities (SRC), pentosan content, dough rheology, and suitability for making sugar snap cookies, to identify the main parameters that could be used in wheat breeding programs for improving cookie quality. Significantly negative correlations were found between water SAC, sucrose SRC, and sugar snap cookie diameter, and between sodium carbonate SAC, alkaline water retention capacity (AWRC), and water soluble pentosan, while significantly positive correlations were obtained between water, sodium carbonate, lactic acid, and sucrose SAC and AWRC. Alveograph parameters were more closely associated with sugar snap cookie quality compared with parameters from farinograph and extensograph except for water absorption. Water SRC was highly and significantly associated with farinograph water absorption, extensograph extensibility, alveograph P (tenacity), and P/L (the ratio of tenacity and extensibility). Regression analyses showed that sucrose SRC and flour particle size could be used to predict the sugar snap cookie diameter. Cluster analysis based on sugar snap cookie diameter indicated that 'Jianmai 1', 'Wanmai 19', and 'Wanmai 48' were characterized by good cookie quality, with low water soluble and total pentosans, water and particularly sucrose SRC, water absorption, and P and P/L values. It also indicated that substantial progress for soft wheat sugar snap cookie quality improvement could be achieved through appropriate use of current elite germplasm. [ABSTRACT FROM AUTHOR]