The construction of a maize-teosinte introgression population and quantitative trait loci analysis of their 21 agronomic traits.

Teosinte is a progenitor species of maize (Zea mays ssp. mays) that retains a significant reservoir of genetic resources unaltered via the domestication process. To harness and explore the genetic reservoirs inherent in teosinte, we used the cultivated publicly inbred line H95 and wild species PI566673 (Zea mays ssp. mexicana) to develop a set of introgression lines (ILs), including 366 BC2F5 lines. Using these lines, 12481 high-quality polymorphic homozygous single nucleotide polymorphisms were converted into 2358 bin markers based on Genotyping by Target Sequencing technology. The homozygous introgression ratio in the ILs was approximately 12.1 % and the heterozygous introgression ratio was approximately 5.7 %. Based on the population phenotypic data across 21 important agronomic traits collected in Sanya and Beijing, 185 and 156 quantitative trait loci (QTLs) were detected in Sanya and Beijing, respectively, with 64 stable QTLs detected in both locations. We detected 12 QTL clusters spanning 10 chromosomes consisting of diverse QTLs related to yield traits such as grain size and weight. In addition, we identified useful materials in the ILs for further gene cloning of related variations. For example, some heterogeneous inbred families with superior genetic purity, shorter target heterozygotes, and some ILs exhibit clear morphological variation associated with plant growth, development, and domestication, manifesting traits such as white stalks, sharp seeds, and cob shattering. In conclusion, our results provide a robust foundation for delving into the genetic reservoirs of teosinte, presenting a wealth of genetic resources and offering insight into the genetic architecture underlying maize agronomic traits.

Artificial Selection Trend of Wheat Varieties Released in Huang-Huai-Hai Region in China Evaluated Using DUS Testing Characteristics.

Wheat has been widely cultivated all over the world. In China, the number of approved wheat varieties has steadily grown since 2010, with the most notable trend in the Huang-Huai-Hai region. Distinctiveness, uniformity, and stability (DUS) are the prerequisites for a new wheat variety to obtain a release permit. Yet, few reports are available on DUS testing characteristics of released wheat varieties. Here, 32 DUS testing characteristics of 195 wheat varieties released in the Huang-Huai-Hai region were investigated to study their artificial selection trend. The results showed that the means, ranges, and coefficients of variation for eight measured characteristics varied greatly, among which the number of sterile spikelets had the largest variation coefficient of all three wheat-growing areas in the Huang-Huai-Hai region. The difference in plant height between the three wheat-growing areas was the most significant. The mean plant height in the northern winter wheat area was the largest, while that in south Huanghuai was the smallest. The released varieties of the three wheat-growing areas in the region had similar artificial selection trends in some characteristics. For instance, flag leaf length and flag leaf width, grain number per ear, and grain volume weight showed an overall upward trend, while the plant height gradually decreased. The clustering results based on DUS testing characteristics showed that artificial selection of characteristics was consistent with ecological adaptation and breeding process as well as pedigree sources. Our findings indicated that with the current breeding objectives, the selection of some non-economic characteristics of wheat varieties, such as awn color, stem color, and glume color, seemed to be able to enrich the genetic diversity of varieties in the Huang-Huai-Hai region. These results could provide guidance for subsequent wheat breeding and production in this region, screening similar varieties, and determining the distinctness of applied varieties in DUS testing.

Identification of interacting proteins of the TaFVE protein involved in spike development in bread wheat.

WD-40 repeat-containing protein MSI4 (FVE)/MSI4 plays important roles in determining flowering time in Arabidopsis. However, its function is unexplored in wheat. In the present study, coimmunoprecipitation and nanoscale liquid chromatography coupled to MS/MS were used to identify FVE in wheat (TaFVE)-interacting or associated proteins. Altogether 89 differentially expressed proteins showed the same downregulated expression trends as TaFVE in wheat line 5660M. Among them, 62 proteins were further predicted to be involved in the interaction network of TaFVE and 11 proteins have been shown to be potential TaFVE interactors based on curated databases and experimentally determined in other species by the STRING. Both yeast two-hybrid assay and bimolecular fluorescence complementation assay showed that histone deacetylase 6 and histone deacetylase 15 directly interacted with TaFVE. Multiple chromatin-remodelling proteins and polycomb group proteins were also identified and predicted to interact with TaFVE. These results showed that TaFVE directly interacted with multiple proteins to form multiple complexes to regulate spike developmental process, e.g. histone deacetylate, chromatin-remodelling and polycomb repressive complex 2 complexes. In addition, multiple flower development regulation factors (e.g. flowering locus K homology domain, flowering time control protein FPA, FY, flowering time control protein FCA, APETALA 1) involved in floral transition were also identified in the present study. Taken together, these results further elucidate the regulatory functions of TaFVE and help reveal the genetic mechanisms underlying wheat spike differentiation.

Emergence of a Novel Chimeric Gene Underlying Grain Number in Rice.

Grain number is an important factor in determining grain production of rice (Oryza sativa L.). The molecular genetic basis for grain number is complex. Discovering new genes involved in regulating rice grain number increases our knowledge regarding its molecular mechanisms and aids breeding programs. Here, we identified GRAINS NUMBER 2 (GN2), a novel gene that is responsible for rice grain number, from "Yuanjiang" common wild rice (O. rufipogon Griff.). Transgenic plants overexpressing GN2 showed less grain number, reduced plant height, and later heading date than control plants. Interestingly, GN2 arose through the insertion of a 1094-bp sequence from LOC_Os02g45150 into the third exon of LOC_Os02g56630, and the inserted sequence recruited its nearby sequence to generate the chimeric GN2 The gene structure and expression pattern of GN2 were distinct from those of LOC_Os02g45150 and LOC_Os02g56630 Sequence analysis showed that GN2 may be generated in the natural population of Yuanjiang common wild rice. In this study, we identified a novel functional chimeric gene and also provided information regarding the molecular mechanisms regulating rice grain number.

Complexity of indica-japonica varietal differentiation in Bangladesh rice landraces revealed by microsatellite markers.

To understand the genetic diversity and indica-japonica differentiation in Bangladesh rice varieties, a total of 151 accessions of rice varieties mostly Bangladesh traditional varieties including Aus, Boro, broadcast Aman, transplant Aman and Rayada varietal groups were genotyped using 47 rice nuclear SSRs. As a result, three distinct groups were detected by cluster analysis, corresponding to indica, Aus and japonica rice. Among deepwater rice varieties analyzed some having particular morphological features that mainly corresponded to the japonica varietal group. Some small seeded and aromatic varieties from Bangladesh also corresponded to the japonica varietal group. This research for the first time establishes that the japonica varietal group is a prominent component of traditional varieties in Bangladesh, particularly in deepwater areas.