The wheat mutant line three-pistil (TP) exhibits three pistils per floret. As TP normally has two or three seeds in each of the florets on the same spike, there is the possibility of increasing the number of grains per spike. Therefore, TP is a highly valuable mutant for breeding and for the study of floral development in wheat. To map the three-pistil gene (Pis1), genotyping-by-sequencing single-nucleotide polymorphism (GBS-SNP) data from an F2 mapping population (CM28 × CM28TP) was used to construct a genetic map that is of significant value. In the present study, a high-density genetic map of wheat containing 2917 GBS-SNP markers was constructed. Twenty-one linkage groups were resolved, with a total length of 2371.40 cM. The individual chromosomes range from 2.64 cM to 454.55 cM with an average marker density of 0.81 cM. The Pis1 gene was mapped using this high-resolution map, and two flanking SNP markers tightly linked to the gene, M70 and M71, were identified. The Pis1 is 3.00 cM from M70 and 1.10 cM from M71. In bread wheat genome, M70 and M71 were found to delimit a physical distance of 3.40 Mb, which encompasses 127 protein-coding genes. To validate the GBS-generated genotypic data and to eliminate missing marker data in the Pis1 region, five Kompetitive Allele-Specific PCR (KASP) assays were designed from corresponding GBS sequences, which harbor SNPs that surround Pis1. Three KASP-SNP markers, KM70, KM71, and KM75, were remapped to the Pis1 gene region. This work not only lays the foundation for the map-based cloning of Pis1 but can also serve as a valuable tool for studying marker-trait association of important traits and marker-assisted breeding in wheat.

Wheat (Triticum aestivum) is one of the most important cereal crops, providing food for humans and feed for other animals. However, its productivity is challenged by various biotic and abiotic stresses such as fungal diseases, insects, drought, salinity, and cold. Transcription factors (TFs) regulate gene expression in different tissues and at various developmental stages in plants and animals, and they can be identified and classified into families according to their structural and specialized DNA-binding domains (DBDs). Transcription factors are important regulatory components of the genome, and are the main targets for engineering stress tolerance. In total, 2407 putative TFs were identified from wheat expressed sequence tags, and then classified into 63 families by using Hmm searches against hidden Markov model (HMM) profiles. In this study, 2407 TFs represented approximately 2.22% of all genes in the wheat genome, a smaller proportion than those reported for other cereals in PlantTFDB V3.0 (3.33%–5.86%) and PlnTFDB (4.30%–6.46%). We assembled information from the various databases for individual TFs, including annotations and details of their developmental stage- and tissue-specific expression patterns. Based on this information, we identified 1257 developmental stage-specific TFs and 1104 tissue-specific TFs, accounting for 52.22% and 45.87% of the 2407 wheat TFs, respectively. We identified 338, 269, 262, 175, 49, and 18 tissue-specific TFs in the flower, seed, root, leaf, stem, and crown, respectively. There were 100, 6, 342, 141, 390, and 278 TFs specifically expressed at the dormant seed, germinating seed, reproductive, ripening, seedling, and vegetative stages, respectively. We constructed a comprehensive database of wheat TFs, designated as WheatTFDB ( http://xms.sicau.edu.cn/wheatTFDB/ ). Approximately 2.22% (2407 genes) of all genes in the wheat genome were identified as TFs, and were clustered into 63 TF families. We identified 1257 developmental stage-specific TFs and 1104 tissue-specific TFs, based on information about their developmental- and tissue-specific expression patterns obtained from publicly available gene expression databases. The 2407 wheat TFs and their annotations are summarized in our database, WheatTFDB. These data will be useful identifying target TFs involved in the stress response at a particular stage of development.

Homologous transformation sterility-1 (HTS-1) is a novel wheat mutant that exhibits pistillody, the transformation of stamens into pistils or pistil-like structures. More extreme phenotypes of this mutation can have six pistils or pistil-like structures without any stamens in a floret. Thus, HTS-1 is highly valuable for studies of wheat hybrid breeding and flower development. Previous studies have shown that two major genes (Pis1 and hts) control pistillody in HTS-1. The Pis1 gene controls the three-pistil trait in the three-pistil wheat mutant and has been mapped on chromosome 2D, but the hts gene has not been mapped or identified. To do so, we crossed HTS-1 with CM28TP (three-pistil mutant) and constructed a high-density linkage map with the F2 population (200 individuals). The map covered 2779.96 cM, and the genetic distance per chromosome ranged from 37.59 cM to 318.95 cM. The average distance between markers was 1.04 cM. We then mapped hts between GBS-SNP markers 4A_109 and 4A_119, separated by 2.0 cM and 5.2 Mb. To find the candidate genes, the hts region was enlarged to 7.2 Mb, encompassing 752 protein-coding genes. We identified TaWin1 as a possible candidate gene after comparing the 752 genes with 206 common differentially expressed genes between pistillody stamens (PS) versus normal stamens (S) and pistils (P) versus S. Real-time PCR indicated that TaWin1 was highly expressed in HTS-1 during the pistil-and-stamen-differentiating stage, at levels approximately 120 times greater than those in CM28TP. Further analysis indicated that TaWin1 was mainly expressed in HTS-1 PS, supporting its status as a candidate gene of hts. Thus, TaWin1 overexpression probably leads to the transformation of stamens into pistils in wheat. The results of this study provide a foundation for further research on stamen and pistil development, with implications for wheat-hybrid breeding programs.

Transcription factors (TFs) regulate plant gene expression in different tissues. To investigate TF genes in rice ( Oryza sativa L.), a genome‐wide TF identification was conducted with the japonica rice genome. This study identified 3078 putative TFs in 59 families. The TF number of the top 10 TF families accounted for 58% of the 3078 rice TFs. The three largest TF families were the myeloblastosis (MYB) superfamily, basic helix–loop–helix (bHLH), and far‐red‐impaired response (FAR1), which contained 413, 228, and 210 TF members, respectively. The expression profiles of the 3078 TF genes were surveyed with the RNA sequencing (RNA‐seq) data of 13 rice tissue types. Based on these expression profiles, we validated 1087 TFs expressed in 13 rice tissue types, which accounted for 35.32% of the 3078 putative TFs. We further analyzed the tissue‐specific TFs in rice. In total, 28, 14, 14, 10, 9, 5, 5, 4, 3, 3, 2, 11, and 1 tissue‐specific TF sequences were identified in the dry seed, pistil, spikelet, aleurone, anther, ovules, embryo 25 d after pollination (DAP), seed 5 DAP, root, leaf, seed 10 DAP, shoot, and endosperm 25 DAP, respectively. Moreover, we constructed RicetissueTFDB ( http://221.237.158.212:50009/index ), a comprehensive and public rice TF database that integrates tissue expression characters, genomic location, and Gene Ontology (GO) terms for each TF. The RicetissueTFDB database will facilitate the identification of target TFs and the functional studies about rice TFs.

As one of the most important crops for oil, olive (Olea europaea L.) is well-known worldwide for its commercial product “virgin olive oil” containing high-content fatty acids and many secondary metabolites. The molecular mechanisms underlying the enhanced oil content in olive remain unclear. To further investigate the molecular mechanisms of olive oil biosynthesis, we selected two olive cultivars, i.e., Kalinjot (JZ) and Coratina (KLD), at three maturity stages (MI-1, MI-3, and MI-6) for transcriptomic analysis based on Nanopore sequencing. Significant differences were observed in oil content between JZ and KLD during three maturity stages. Enrichment analysis revealed significant enrichment of differentially expressed genes (DEGs) in metabolic pathways of photosynthesis, amino acid biosynthesis, response to stress, and energy metabolism, in particular, fatty acid metabolism. A total of 170 (31.54% of 539 genes involved in oil synthesis) DEGs were further investigated based on expression analysis to identify their molecular functions in oil biosynthesis in olive. A co-expression network based on 714 transcription factors and their targeted genes in oil biosynthesis was constructed. Our study provided novel experimental evidence to investigate the molecular mechanisms of olive oil biosynthesis and to improve the breeding of olive varieties with enhanced oil contents.

Crop male sterility has great value in theoretical research and breeding application. HTS-1, whose stamens transformed into pistils or pistil-like structures, is an important male sterility material selecting from Chinese Spring three-pistil (CSTP) wheat. However the molecular mechanism of pistillody development in HTS-1 remains a mystery. RNA-seq data of 11 wheat tissues were obtained from the National Center for Biotechnology Information (NCBI), including the stamens of CSTP and the pistils and pistillodic stamen of HTS-1. The Salmon program was utilized to quantify the gene expression levels of the 11 wheat tissues; and gene quantification results were normalized by transcripts per million (TPM). In total, 58,576 genes were used to construct block-wise network by co-expression networks analysis (WGCNA) R package. We obtained all of modules significantly associated with the 11 wheat tissues. AgriGO V2.0 was used to do Gene Ontology (GO) enrichment analysis; and genes and transcription factors (TFs) in these significant modules about wheat pistillody development were identified from GO enrichment results. Basic local alignment search tool (BLAST) was used to align HTS-1 proteins with the published pistillody-related proteins and TFs. Genes about wheat pistillody development were analyzed and validated by qRT-PCR. The MEturquoise, MEsaddlebrown, MEplum, MEcoral1, MElightsteelblue1, and MEdarkslateblue modules were significantly corelated to pistillodic stamen (correlation p < 0.05). Moreover, 206 genes related to carpel development (GO:0048440) or gynoecium development (GO:0048467) were identified only in the MEturquoise module by Gene Ontology (GO) analysis, and 42 of 206 genes were hub genes in MEturquoise module. qRT-PCR results showed that 38 of the 42 hub genes had highly expressed in pistils and pistillodic stamens than in stamens. A total of 15 pistillody development-related proteins were validated by BLAST. Transcription factors (TFs) were also analyzed in the MEturquoise module, and 618 TFs were identified. In total, 56 TFs from 11 families were considered to regulate the development of pistillodic stamen. The co-expression network showed that six of HB and three of BES1 genes were identified in 42 hub genes. This indicated that TFs played important roles in wheat pistillody development. In addition, there were 11 of ethylene-related genes connected with TFs or hub genes, suggesting the important roles of ethylene-related genes in pistillody development. These results provide important insights into the molecular interactions underlying pistillody development.