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With the application of hybrid wheat, lodging is becoming one of the major factors limiting high yield in its production. However, few studies have focused on combining ability and heterosis analysis of stem-related traits. In this study, 24 crosses were made according to NCII genetic design, using the three (photo-sensitive male sterile lines)×eight (restorer lines) incomplete diallel crosses. The length of basal second internode (LBSI) and breaking strength of basal second internode (BSBSI) as well as other stem-related traits were used to perform the principal component analysis (PCA), combining ability and heterosis analysis. The PCA results showed that the variables could be classified into two main factors, which were named as the positive factor (factor 1) and the negative factor (factor 2), and accounted for 52.3 and 33.2%, respectively, of the total variance in different variables, combined with the analysis for index weight indicated that the factor 1-related traits play positive roles in lodging resistance formation of hybrids. Combining ability variance analysis indicated that its genetic performance was mainly dominated by additive gene effects, and the hybrid combinations with higher lodging resistance can be selected by using of 14GF6085 (R1), 14GF6343-2 (R4), 14GF6937 (R6), 14GF7433-1 (R7), and BS1086 (M3), which are with the features with lower general combining ability (GCA) effects of factor 2-related traits whereas higher GCA effects of factor 1-related traits. The heterosis analysis showed that the wide range of heterosis varied with the traits and combinations, and GCA or specific combining ability (SCA) effects of factor 1-related traits except wall thickness of basal second internode (WTBSI) were positively and closely related to the heterosis of lodging resistance. Generally, the correlation coefficients of heterosis to GCA effects of sterile lines (GCAm) of factor 1-related traits are significantly higher than that to GCA of restorer lines (GCAr) and SCA, combined with the higher GCAmvariance values of factor 1-related traits compared to GCAr, the GCAmof factor 1-related traits should be particularly considered when breeding hybrid combinations. The heritability analysis showed that the narrow-sense heritability of the diameter of basal second internode (DBSI) and the center of gravity height (TCGH) were obviously lower (<60%) than other traits, suggesting that these two traits were suitable for selection in higher generation for parental breeding. These could provide a theoretical basis for parental breeding and heterosis utilization of lodging resistance.

AbstractThe pollen fertility of photoperiod/temperature sensitive genic male sterile (P/TGMS) wheat is controlled by light and/or temperature. Circular RNA (circRNA) and long non-coding RNA (lncRNA) are known to participate in the development of anthers in plants, but their impact on male sterility in the P/TGMS line is not well understood. In this study, we carried out high-throughput sequencing to investigate the differential expression of lncRNAs and circRNAs and their biological functions in anthers of photo-thermosensitive genic male sterile (PTGMS) wheat line BS366-42L during the transition phase of male fertility under four different photoperiod and temperature treatments. Eight lncRNAs, 40 mRNAs and three circRNAs were screened out and thought as essential candidates that closely related to male sterility. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were performed to predict the potential functions of differentially expressed RNAs. The results indicated that carbohydrate-related metabolism was important for male sterility in the wheat PTGMS line BS366-42L. lncRNA/circRNA-mRNA-miRNA (ceRNA) integrate networks were constructed to reflect their complex inner association with male sterility. Our study provides a systematic perspective on the potential function of RNAs in male fertility in PTGMS lines of wheat.

Because of the yield increase of 3.5–15% compared to conventional wheat, hybrid wheat is considered to be one of the main ways to greatly improve the wheat yield in the future. In this study, we performed a principal component analysis (PCA) on two-line hybrids wheat and their parents using the grain weight (GW), the length of spike (LS), the kernel number of spike (KSN), and spike number (SPN) as variables. The results showed that the variables could be classified into three main factors, the weight factor (factor 1), the quantity factor 1 (factor 2) and the quantity factor 2 (factor 3), which accounted for 37.1, 22.6 and 18.5%, respectively of the total variance in different agronomic variables, suggesting that the GW is an important indicator for evaluating hybrid combinations, and the grain weight of restorer line (RGW) could be used as a reference for parents selection. The hybrid combination with a higher score in factor 1 direction and larger mid-parent heterosis (MPH) of the GW and its parents were used to carry out the analysis of grain filling, 1-aminocylopropane-1-carboxylicacid (ACC) and polyamine synthesis related genes. The results suggested that the GW of superior grain was significantly higher than that of inferior grains in BS1453×JS1 (H) and its parents. Both grain types showed a weight of H between BS1453 (M) and JS1(R), and a larger MPH, which may be caused by their differences in the active filling stage and the grain filling rate. The ADP-glucose pyrophosphorylase (AGPase), granule bound starch synthase I (GBSSI), starch synthase III (SSS), and starch branching enzyme-I (SBE-I) expression levels of H were intermediated between M and R, which might be closely related to MPH formation of the GW. Compared with R and H, the GW of M at maturity was the lowest. The expression levels of spermidine synthase 2 (Spd2), ornithine decarboxylase (ODC) and S-adenosylmethionine decarboxylase (SAMDC) had significantly positive correlations with the grain filling rate (r=0.77*, 0.51*, 0.59*), suggesting their major roles in the grain filling and heterosis formation. These provide a theoretical basis for improving the GW of photo-thermo-sensitive male sterile lines (PTSMSL) by changing the endogenous polyamine synthesis in commercial applications.

Identification of stable quantitative trait loci (QTL) for yield-related traits across populations and environments is crucial for wheat breeding and genetic studies. Consensus maps also play important roles in wheat genetic and genomic researches. In the present study, a wheat consensus map was constructed using a doubled haploid (DH) population derived from Jinghua 1×Xiaobaidongmai (JX) and an F2population derived from L43×Shanxibaimai (LS) using BAAFS AFFY wheat 90K single nucleotide polymorphism (SNP) array. A total of 44503 SNP markers were mapped on the constructed consensus map, covering 5437.92 cM across 21 chromosomes. The consensus map showed high collinearity with the individual maps and the wheat reference genome IWGSC RefSeq v2.1. Phenotypic data on eight yield-related traits were collected in the JX population and F2:3and F2:4populations of LS in six, two and two environments, respectively, and used for QTL analysis. Inclusive composite interval mapping (ICIM) identified 32 environmentally stable QTL for eight yield-related traits. Among them, four QTL, i.e., QPH.baafs-4B, QKNS.baafs-4B, QTGW.baafs-4Band QSL.baafs-5A.3, were detected across mapping populations and environments, and seven stable QTL i.e., QPH.baafs-2B, QKNS.baafs-3D, QSL.baafs-3D, QKW.baafs-4B, QPH.baafs-5D, QPH.baafs-6A.1and QSL.baafs-6A, are likely to be new. The physical region of 17.25-44.91 Mb on chromosome 4B was associated with six yield-related traits, which is an important region for wheat yield. The physical region around the dwarfing gene Rht24contained QTL for KL, KW, SL and TGW, which are either from a pleiotropic effect of Rht24or closely linked loci. Two hundred and fifty-four promising candidate genes were identified for the stable QTL. Among them, TraesCS5A03G1264300, TraesCS1B03G0624000and TraesCS6A03G0697000were particularly noteworthy due to their homologous genes have similar functions for the corresponding traits. The constructed consensus map and the identified QTL along with their candidate genes will facilitate the genetic dissection of wheat yield-related traits and accelerate the development of wheat cultivars with desirable plant morphology and high yield.

Assessment of variety distinctness is important for both the registration and the protection of particular variety. However, the current testing system, which assesses a range of morphological characters of each pair of varieties grown side-by-side, is time-consuming and is not suitable for the assessment of hundreds of samples. The objective of this study was to develop a procedure for the assessment of wheat variety distinctness using simple sequence repeat (SSR) markers. A comparison between the molecular and morphological profile of 797 varieties was made. On the basis of the comparison, pairs of varieties with a genetic similarity value (GSV) ≤90% were deemed to be distinct, accounting for ∼85% of varieties assessed in wheat regional trials. For the remaining ∼15% of varieties, GSVs between different varieties were >90%, among which ∼35% were not distinct and the other ∼65% were distinct. Therefore, if given a GSV>90%, the pairs of varieties should be morphologically assessed in the field. To avoid any errors in the assessments, we proposed the elimination of contaminant plants from the sample before comparing the varietal genotypes, scoring of the genotype at each locus with a pair of allele numbers when constructing a molecular profile, and faithfully recording two alleles at a non-homozygous locus. To reduce the workload and cost, a three-grade markers comparison among varieties is suggested. In addition, 80 SSR markers and a technical procedure for assessment of wheat variety distinctness have been proposed. Based on the procedure, the distinctness assessment of ∼85% of all wheat varieties is completed in our laboratory annually. Consequently, total field assessment has been reduced considerably.