Genetic and molecular characterization of determinant of six-rowed spike of barley carrying vrs1.a4.

KEY MESSAGE: Decisive role of reduced vrs1 transcript abundance in six-rowed spike of barley carrying vrs1.a4 was genetically proved and its potential causes were preliminarily analyzed. Six-rowed spike 1 (vrs1) is the major determinant of the six-rowed spike phenotype of barley (Hordeum vulgare L.). Alleles of Vrs1 have been extensively investigated. Allele vrs1.a4 in six-rowed barley is unique in that it has the same coding sequence as Vrs1.b4 in two-rowed barley. The determinant of row-type in vrs1.a4 carriers has not been experimentally identified. Here, we identified Vrs1.b4 in two-rowed accessions and vrs1.a4 in six-rowed accessions from the Qinghai-Tibet Plateau at high frequency. Genetic analyses revealed a single nuclear gene accounting for row-type alteration in these accessions. Physical mapping identified a 0.08-cM (~ 554-kb) target interval on chromosome 2H, wherein Vrs1 was the most likely candidate gene. Further analysis of Vrs1 expression in offspring of the mapping populations or different Vrs1.b4 and vrs1.a4 lines confirmed that downregulated expression of vrs1.a4 causes six-rowed spike. Regulatory sequence analysis found a single 'TA' dinucleotide deletion in vrs1.a4 carriers within a 'TA' tandem-repeat-enriched region ~ 1 kb upstream of the coding region. DNA methylation levels did not correspond to the expression difference and therefore did not affect Vrs1 expression. More evidence is needed to verify the causal link between the 'TA' deletion and the downregulated Vrs1 expression and hence the six-rowed spike phenotype.

De novo assembly and characterization of the root transcriptome of Aegilops variabilis during an interaction with the cereal cyst nematode.

BACKGROUND: Aegilops variabilis No.1 is highly resistant to cereal cyst nematode (CCN). However, a lack of genomic information has restricted studies on CCN resistance genes in Ae. variabilis and has limited genetic applications in wheat breeding. RESULTS: Using RNA-Seq technology, we generated a root transcriptome at a sequencing depth of 4.69 gigabases of Ae. variabilis No. 1 from a pooled RNA sample. The sample contained equal amounts of RNA extracted from CCN-infected and untreated control plants at three time-points. Using the Trinity method, nearly 52,081,238 high-quality trimmed reads were assembled into a non-redundant set of 118,064 unigenes with an average length of 500 bp and an N50 of 599 bp. The total assembly was 59.09 Mb of unique transcriptome sequences with average read-depth coverage of 33.25×. In BLAST searches of our database against public databases, 66.46% (78,467) of the unigenes were annotated with gene descriptions, conserved protein domains, or gene ontology terms. Functional categorization further revealed 7,408 individual unigenes and three pathways related to plant stress resistance. CONCLUSIONS: We conducted high-resolution transcriptome profiling related to root development and the response to CCN infection in Ae. variabilis No.1. This research facilitates further studies on gene discovery and on the molecular mechanisms related to CCN resistance.

Starch granule-associated proteins of hull-less barley (Hordeum vulgare L.) from the Qinghai-Tibet Plateau in China.

BACKGROUND: The starch granule-associated proteins (SGAPs) are the minor components of the starch granules and a majority of them are believed to be starch biosynthetic enzymes. The Qinghai-Tibet Plateau in China, one of the centres of origin of cultivated barley, is abundant in hull-less barley resources which exhibit high polymorphism in SGAPs. RESULTS: The SGAPs of hull-less barley from Qinghai-Tibet Plateau were analysed by one-dimensional (1-D) SDS-PAGE, 2-D PAGE and ESI-Q-TOF MS/MS. In the 1-D SDS-PAGE gel, four proteins including a 80 kDa starch synthase, actin, actin 4 and ATP synthase ß-subunit were identified as novel SGAPs. A total of six different bands were identified as starch granule-bound starch synthase I (GBSSI) and the segregation of the novel GBSSI bands in F(1) and F(2) seeds derived from yf127 × yf70 was in accordance with Mendel's law. In the 2-D PAGE gel, 92 spots were identified as 42 protein species which could be classified into 15 functional groups. Thirteen protein species were identified as SGAPs for the first time and multiple spots were identified as GBSSI. CONCLUSION: This study revealed novel SGAPs in hull-less barley from the Qinghai-Tibet Plateau in China and these will be significant in further studies of starch biosynthesis in barley.

[Genetic analysis of contribution of low-molecular-weight glutenin subunits to dough strength in common wheat].

Locus-specific primers of low-molecular-weight glutenin subunit (LMW-GS) genes and gliadin bands tightly linked to LMW-GS genes were analyzed to evaluate the effect of LMW-GS genes on dough strength in common wheat (Triticum aestivum L.). Analysis of the F9 progeny from two crosses '99G45/Jing771' and 'Pm97034/J771' showed that the LMW-GS genes located at the Glu-B3 locus from the three parents had six Cysteine, but 'PB' (define) had a seven amino-acid deletion in the repetitive to 'GB' and 'JB' (define these abbreviations) and amino-acid substitution, two of which would be expected to cause changes in hydrophilicity.

[SGP polymorphism in cultivated naked barley from Qinghai-Tibet plateau in China and the relationship between SGPs and starch content].

Starch granule proteins (SGPs) are minor components bound with starch granule, which mutation may be related to starch properties. This study investigated the variation of SGPs in cultivated naked barley from Qinghai-Tibet Plateau in China for the first time, and the relationship between SGPs and starch content was preliminarily done. Ten major SGPs and 16 types of patterns were present in 66 cultivated naked varieties, indicating SGPs in cultivated naked barley from Qinghai-Tibet Plateau in China are polymorphic. SGPs in Tibet and Sichuan naked barley were greatly different and SGPs were specific to origin of site. Significance test analysis demonstrates SGPs described in this study except for SGP1 may be related with the variation of starch content in different naked barley.

Cloning and characterization of four B-hordein genes from Tibetan hull-less barley (Hordeum vulgare subsp. vulgare).

Four B-hordein genes, designated BH1-BH4, were cloned using PCR amplification from two hull-less barley cultivars, ZQ7239 and ZQ148, collected from Tibet. The results of sequencing indicated that BH1-BH4 contained complete open reading frames (ORFs). Comparison of their predicted polypeptide sequences with the published sequences suggested that they all share the same basic protein structure. Phylogenetic analysis indicated that the deduced amino-acid sequences of BH1-BH4 genes were more closely related to B-hordeins from cultivated barley (Hordeum vulgare L.) than to any other prolamins from wild barley and Aegilops tauschii. Comparison of the coding regions of BH1-BH4 genes showed that BH1 had a lower sequence identity to other previously published B-hordeins than the other three B-hordeins obtained in this study. BH1 was then cloned in a bacterial expression vector based on bacteriophage T7 RNA polymerase. The resulting plasmid produced a 28.15 kDa protein in Escherichia coli. The potential value of B-hordein genes in grain quality improvement of hull-less barley has been discussed.

[Morphology, cytogenetics of intergeneric hybrid between Aegilops taucchii and Dasypyrum villosum].

"Aegilops tauschii x Dasypyrum villosum" F1 hybrids were obtained by the combination of hybridization and embryo culture in vitro. Chromosome pairing behavior in meiosis of the hybrid F1 was carried out. Results showed that in an average , 1.25 rod bivalents were observed in one PMC, meiotic configuration was 2n=14=11.49 I + 1.25 II (Xta=1.25) and most of PMCs possessed 1 approximately 5(rod) bivalens, indicating that the relatively high homeology was detected between the D genome of Ae. tauschii and the V genome of D. villosum. The morphological differences between F1 hybrids and their parents were significant. F1 plants were highly self-sterile, but partially self-fertile after treated by chromosome doubling technique.

[Chromosome analysis of Chongqing thermo-photo sensitive male sterile wheat].

Seed gliadin acid-polyacrylamide-gel-electrophoresis (APAGE) and chromosome C-banding techniques were used to identify chromosome constitution of Chongqing thermo-photo sensitive male sterile wheat. Results showed that 1BS of the male sterile lines was substituted by 1RS of rye. They were 1B/1R wheat with Triticum aestivum cytoplasm.