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Additional file 1: Table S1. Genetic map of wheat developed using the RIL population derived from the cross between BainongAK58 and Bima4. Table S2. Phenotypic variation for SL and KNS in the RIL population. Table S3. Seventy wheat cultivars derived from Bima4.

Fusarium head blight (FHB), mainly caused by Fusarium graminearum, has become one of the most serious diseases that damage wheat. The TaPFT (pore-forming toxin-like) and TaHRC (histidine-rich calcium-binding protein) genes at the quantitative trait locus Fhb1 were identified to confer resistance to FHB in the wheat cultivar Sumai 3. In this study, a wheat ricin B-like lectin gene (designated TaRBL) that interacted with TaPFT was isolated by a yeast two-hybrid screen of a wheat cDNA library. A yeast two-hybrid and bimolecular fluorescence complementation study further verified that TaRBL interacted with TaPFT but not with TaHRC. Gene expression studies showed that upon F. graminearum infection, TaRBL expression was upregulated in resistant cultivars but downregulated in susceptible cultivars. Furthermore, knockdown of TaRBL expression by barley stripe mosaic virus-induced gene silencing significantly reduced the resistance of wheat to FHB in both the resistant cultivar Sumai 3 and the susceptible cultivar Jimai 22. Thus, we conclude that TaRBL encodes a ricin B-like lectin protein that interacts with TaPFT and is involved in resistance to FHB in wheat.

Changes in rhizosphere pH play an important role in wheat growth. To investigate the relationship between changes in rhizosphere pH and the growth of winter wheat roots and to explore the regulatory mechanism of acid and alkali resistance in winter wheat roots, the semi-winter wheat varieties Aikang 58 (AK58) and Bainong 4199 (BN4199) were used as materials for hydroponic experiments. Three pH levels (4.0, 6.5, and 9.0, with 6.5 as control) were applied during the wheat seedling stage. The results showed that the shoot and root biomass of the plants significantly decreased compared with the control under acid-base stress, with a more significant decrease with acid stress than alkali stress. Compared with the control, the root/shoot ratio increased under alkali stress and decreased under acid stress. The wheat root system showed H+ net efflux at pH 6.5 and 9.0, and the H+ net efflux rate at pH 4.0 was significantly lower than the control. The root activity of wheat was higher than the control at pH 9.0 and lower at pH4.0. The change of root pH was showed pH 4.0 < pH 6.5 < pH 9.0. Correlation analysis showed that changes in H+ net flux were significantly positively correlated to root activity and root pH. The H+ efflux rate and root activity of BN4199 were highe r than AK58 under acid and alkali stress, and the root/shoot ratio was relatively high, indicating strong acid and alkali resistance. We conclude that wheat could adapt to poor acid-base environments by adjusting root H+ net flux, and in practice, the root/shoot ratio could be used as index for the rapid determination of acid-base tolerance in wheat at the seedling stage.

Leaf colour plays an important role in plant growth and development. In this study, a stably inherited yellow–green leaf mutation, temporarily designated yglw-1, was initially isolated from progenies of wheat (Triticum aestivum L.) cross Bainong58409/Caifumai. The yellow-leaf phenotype could be observed in the yglw-1 mutant during the seedling stage, and then the yellow leaves gradually progressed from the bottom to the top throughout development. Compared with its sister line Cf5019-21 with a normal leaf-colour phenotype, the main agronomic traits of the yglw-1 mutant including spike length, number of kernels per spike and 1000-kernel weight were significantly decreased. Measurement of chlorophyll contents showed that chlorophylls a and b in the third top leaf at the jointing stage and the penultimate leaf and third top leaf at the heading stage were obviously lower in yglw-1 than in Cf5019-21. Genetic analysis indicated that the yellow–green leaf trait was controlled by a single recessive gene. Bulked segregant analysis found that two published simple sequence repeat (SSR) markers and four expressed sequence tag-sequence tagged site (EST-STS) markers were linked to the yglw-1 gene, and BE494262 was the most closely linked marker to yglw-1, at a genetic distance of 2.3 cM. To increase the density of the genetic map, 135 novel SSR markers at a certain distance near the marker BE494262 were developed according to SSR loci detected in the Chinese Spring reference sequence. Of these, nine SSR markers detected polymorphic fragments between the two parents as well as between the contrasting DNA bulks. Finally, the yglw-1 gene was mapped between SSR markers Xhwm1 and Xhwm43 and showed genetic distances 1.9 cM and 23.9 cM on chromosome 2BS. These findings can facilitate candidate-gene prediction and map-based cloning of the yglw-1 gene.

Grain-size is one of the yield components, and the first 14 days after pollination (DAP) is a crucial stage for wheat grain-size formation. To understand the mechanism of grain-size formation at the whole gene expression level and to identify the candidate genes related to grain pattern formation, cDNA libraries from immature grains of 5 DAP and 14 DAP were constructed. According to transcriptome analysis, a total of 12,555 new genes and 9,358 differentially expressed genes (DEGs) were obtained. In DEGs, 2,876, 3,357 and 3,125 genes were located on A, B and D subgenome respectively. 9,937 (79.15%) new genes and 9,059 (96.80%) DEGs were successfully annotated. For DEGs, 4,453 were up-regulated and 4,905 were down-regulated at 14 DAP. The Gene Ontology (GO) database indicated that most of the grain-size-related genes were in the same cluster. The Kyoto Encyclopedia of Genes and Genomes (KEGG) database analysis showed that 130, 129 and 20 DEGs were respectively involved in starch and sucrose metabolism, plant hormone signal transduction and ubiquitin-mediated proteolysis. Expression levels of 8 randomly selected genes were confirmed by qRT-PCR, which was consistent with the transcriptome data. The present database will help us understand the molecular mechanisms underlying early grain development and provide the foundation for increasing grain-size and yield in wheat breeding programs.

EnglishIn this study, a non-destructive, high-throughput, endosperm-based DNA extraction method was developed. To verify the nondestructive nature of this method, a germination test was performed on 288 seeds after sampling their endosperm, which gave a seedling emergence rate that was higher (97.6%) than that of the control group (92%). To confirm the feasibility of the new method, DNA was extracted from plants of a BC1F2 population by two different methods, namely, from endosperm using our rapid, high-throughput method (ER-DNAand from young leaves emerging from the same sampled seed using the CTAB method (LC-DNA). The ER-DNA was undetectable by agarose gel electrophoresis, but was found to be an adequate replacement for LC-DNA for the amplification and detection of simple sequence repeats (SSRs). Further analysis revealed that ER-DNA was generally suitable for the generation of specific 500–750-bp fragments, but not for the amplification of 1,000–2,000-bp fragments. Our rapid, high-throughput method therefore has no deleterious effects on wheat seeds and yields DNA for SSR genotyping that is a suitable alternative to traditionally obtained DNA. portuguesNeste estudo, foi desenvolvido um metodo de extracao de DNA nao destrutivo, de alto debito e endosperma. Para verificar a natureza nao destrutiva deste metodo, um teste de germinacao foi realizado em 288 sementes apos a amostragem do endosperma, o que deu uma taxa de emergencia de plântulas maior (97,6%) do que a do grupo controle (92%). Para confirmar a viabilidade do novo metodo, o DNA foi extraido de plantas de uma populacao de BC1F2 por dois metodos diferentes, a saber, do endosperma usando nosso metodo rapido de alto rendimento (ER-DNA) e de folhas jovens que emergem da mesma semente amostrada usando o metodo CTAB (LC-DNA). O ER-DNA foi indetectavel por eletroforese em gel de agarose, mas foi encontrado como uma substituicao adequada para LC-DNA para a amplificacao e deteccao de repeticoes simples de sequencia (SSRs). Uma analise posterior revelou que o ER-DNA era geralmente adequado para a geracao de fragmentos especificos de 500-750 pb, mas nao para a amplificacao de fragmentos de 1.000-2.000 pb. Nosso metodo rapido e de alto debito, portanto, nao tem efeitos deleterios sobre as sementes de trigo e produz DNA para a genotipagem de SSR que e uma alternativa adequada ao DNA obtido tradicionalmente

Agropyron elongatum (Host.) Neviski (synonym, Thinopyrum ponticum Podp., 2n = 70) has been used extensively as a valuable source for wheat breeding. Numerous chromosome fragments containing valuable genes have been successfully translocated into wheat from A. elongatum. However, reports on the transfer of powdery mildew resistance from A. elongatum to wheat are rare. In this study, a novel wheat-A. elongatum translocation line, 11-20-1, developed and selected from the progenies of a sequential cross between wheat varieties (Lankaoaizaoba, Keyu 818 and BainongAK 58) and A. elongatum, was evaluated for disease resistance and characterized using molecular cytogenetic methods. Cytological observations indicated that 11-20-1 had 42 chromosomes and formed 21 bivalents at meiotic metaphase I. Genomic in situ hybridization analysis using whole genomic DNA from A. elongatum as a probe showed that the short arms of a pair of wheat chromosomes were replaced by a pair of A. elongatum chromosome arms. Fluorescence in situ hybridization, using wheat D chromosome specific sequence pAs1 as a probe, suggested that the replaced chromosome arms of 11-20-1 were 5DS. This was further confirmed by wheat SSR markers specific for 5DS. EST-SSR and EST-STS multiple loci markers confirmed that the introduced A. elongatum chromosome arms belonged to homoeologous group 5. Therefore, it was deduced that 11-20-1 was a wheat-A. elongatum T5DL∙5AgS translocation line. Both resistance observation and molecular marker analyses using two specific markers (BE443538 and CD452608) of A. elongatum in a F2 population from a cross between line 11-20-1 and a susceptible cultivar Yannong 19 verified that the A. elongatum chromosomes were responsible for the powdery mildew resistance. This work suggests that 11-20-1 likely contains a novel resistance gene against powdery mildew. We expect this line to be useful for the genetic improvement of wheat.

Winter wheat (Triticum aestivum L.) production in the North China Plain (NCP) is threatened by wheat lodging. Therefore, enhancing plant lodging resistance by improving stem quality traits is crucial to maintaining high stable yields of winter wheat. A consecutive 7-year field experiment was conducted to study the effects of stem traits on lodging resistance and the yield of four winter wheat cultivars (Bainong 418, Aikang 58, Wenmai 6 and Zhoumai 18). The results indicated that rainfall is often accompanied by strong winds that can cause lodging in the field. Stalk bending strength and wall thickness of the second internode showed significant negative correlations with lodging index, and a higher lodging index indicated increased lodging risk, which, in turn, could seriously affect the grain yield of wheat. Significant regression relationships were observed between lodging index and population lodging resistance strength, as measured using a crop lodging resistance electronic measuring device. Statistical analysis revealed that yield components and the grain yield of Bainong 418 were higher than those of the other cultivars; there was no significant difference between Bainong 418 and Aikang 58 in lodging index, stalk bending strength or single-stalk and population lodging resistance strengths at anthesis and the middle filling stages, but the mean plant height of Bainong 418 was significantly higher than that of Aikang 58. These results provide a new and reliable method for assessing lodging resistance capacity and indicate that greater lodging resistance, as determined by simultaneously considering plant height and basal stem strength, is an important way to achieve high, stable yield in winter wheat.

The development of alien substitution lines is important for transferring useful genes of exotic species into bread wheat. In situ hybridization, SSR and EST-SSR marker analysis were used to identify a wheat–Thinopyrum intermedium substitution line designated as Zhong 199. Zhong 199 was detected with the chromosome number 2n=42 and stable agronomic traits were evaluated during the 2012 field harvest season. Genomic in situ hybridization analysis with the genomic Th. intermedium DNA as a probe showed that Zhong 199 contained a pair of Th. intermedium chromosomes. Fluorescence in situ hybridization, using a repetitive sequence, pAs1, derived from Aegilops squarrosa L., indicated the replacement of chromosome 2D of wheat in the wheat–Th. intermedium substitution line. Seven SSR markers specific for chromosome 2D of wheat further confirmed that the substituted wheat chromosome was 2D in the substitution line. Such result was also confirmed by using EST-SSR marker analysis. This study provided some useful information for effective exploitation of the source of genetic variability for the improvement of wheat.