Morphological Characterization and Integrated Transcriptome and Proteome Analysis of Organ Development Defective 1 (odd1) Mutant in Cucumis sativus L.

Cucumber (Cucumis sativus L.) is an economically important vegetable crop with the unique growth habit and typical trailing shoot architecture of Cucurbitaceae. Elucidating the regulatory mechanisms of growth and development is significant for improving quality and productivity in cucumber. Here we isolated a spontaneous cucumber mutant organ development defective 1 (odd1) with multiple morphological changes including root, plant stature, stem, leaf, male and female flowers, as well as fruit. Anatomical and cytological analyses demonstrated that both cell size and number decreased, and the shoot apical meristem (SAM) was smaller in odd1 compared with WT. Pollen vigor and germination assays and cross tests revealed that odd1 is female sterile, which may be caused by the absence of ovules. Genetic analysis showed that odd1 is a recessive single gene mutant. Using the MutMap strategy, the odd1 gene was found to be located on chromosome 5. Integrated profiling of transcriptome and proteome indicated that the different expression genes related to hormones and SAM maintenance might be the reason for the phenotypic changes of odd1. These results expanded the insight into the molecular regulation of organ growth and development and provided a comprehensive reference map for further studies in cucumber.

A fragment substitution in the promoter of CsHDZIV11/CsGL3 is responsible for fruit spine density in cucumber (Cucumis sativus L.).

KEY MESSAGE: The indel in the promoter of CsHDZIV11 co-segregates with fruit spine density and could be used for molecular breeding in cucumber. Fruit spine density is an important quality trait for marketing in cucumber (Cucumis sativus L.). However, the molecular basis of fruit spine density in cucumber remains unclear. In this study, we isolated a mutant, few spines 1 (fs1), from CNS2 (wild type, WT), a North China-type cucumber with a high density of fruit spines. Genetic analysis showed that fs1 was controlled by a single recessive Mendelian factor. Bulked segregant analysis combined with genome resequencing were used for mapping fs1 in the F2 population derived from a cross between the fs1 mutant and WT, and it was located on chromosome 6 through association analysis. To develop more polymorphic markers to locate fs1, another F2 population was constructed from the cross between fs1 and 'Chinese long' 9930. Then, fs1 was narrowed down to a 110.4-kb genomic region containing 25 annotated genes. A fragment substitution was identified in the promoter region of Csa6M514870 between fs1 and WT. This fragment in fs1 was also present in wild cucumber. Csa6M514870 encodes a PDF2-related protein, a homeodomain-leucine zipper IV transcription factor (CsHDZIV11/CsGL3) sharing high identity and similarity with proteins related to trichome formation or epidermal cell differentiation. Quantitative reverse-transcription PCR revealed a higher expression level of CsHDZIV11 in young fruits from fs1 compared to WT. A molecular marker based on this indel co-segregated with the spine density. This work provides a solid foundation not only for understanding the molecular mechanism of fruit spine density, but also for molecular breeding in cucumber.

The identification of Cucumis sativus Glabrous 1 (CsGL1) required for the formation of trichomes uncovers a novel function for the homeodomain-leucine zipper I gene.

The spines and bloom of cucumber (Cucumis sativus L.) fruit are two important quality traits related to fruit market value. However, until now, none of the genes involved in the formation of cucumber fruit spines and bloom trichomes has been identified. Here, the characterization of trichome development in wild-type (WT) cucumber and a spontaneous mutant, glabrous 1 (csgl1) controlled by a single recessive nuclear gene, with glabrous aerial organs, is reported. Via map-based cloning, CsGL1 was isolated and it was found that it encoded a member of the homeodomain-leucine zipper I (HD-Zip I) proteins previously identified to function mainly in the abiotic stress responses of plants. Tissue-specific expression analysis indicated that CsGL1 was strongly expressed in trichomes and fruit spines. In addition, CsGL1 was a nuclear protein with weak transcriptional activation activity in yeast. A comparative analysis of the digital gene expression (DGE) profile between csgl1 and WT leaves revealed that CsGL1 had a significant influence on the gene expression profile in cucumber, especially on genes related to cellular process, which is consistent with the phenotypic difference between csgl1 and the WT. Moreover, two genes, CsMYB6 and CsGA20ox1, possibly involved in the formation of cucumber trichomes and fruit spines, were characterized. Overall, the findings reveal a new function for the HD-Zip I gene subfamily, and provide some candidate genes for genetic engineering approaches to improve cucumber fruit external quality.

Effect of Al Additions and Cooling Rate on the Microstructure and Mechanical Properties of Austenite FeMnAlC Steels.

The precipitation behavior of κ-carbide and its effects on mechanical properties in Fe-30Mn-xAl-1C (x = 7-11%) steels under water quenching and furnace cooling are studied in the present paper. TEM, XRD, EPMA were employed to characterize the microstructure, and tensile test and the Charpy impact test were used to evaluate mechanical properties. The results show that the density decreases by 0.1 g/cm3 for every 1 wt.% of Al addition. The excellent mechanical properties of tensile strength of 880 MPa and impact absorption energy of 120-220 J at -40 °C with V notch were obtained, with both solid solution and precipitation strengthening results in the yield strength increasing by about 57.5 MPa with per 1% Al addition in water-quenched samples. The increasing of yield strength of furnace-cooled samples comes from the relative strengthening of κ-carbides, and the strengthening potential reaches 107-467 MPa. The lower the cooling rate, the easier it is to promote the precipitation of κ-carbides and the formation of ferrite. The partitioning of C, Mn, Al determines the formation of κ-carbides at a given Al addition, and element partition makes the κ-carbides sufficiently easy to precipitate at a low cooling rate. The precipitation of κ-carbides improves strength and does not significantly reduce the elongation, but significantly reduces the impact absorption energy when Al addition ≥ 8%.

Combined modifications of CaO and liquid fraction of digestate for augmenting volatile fatty acids production from rice straw: Microbial and proteomics insights.

The modification sequence of chemical (CaO) and biological (liquid fraction of digestate, LFD) for augmenting volatile fatty acids (VFAs) production from rice straw was investigated in this study. The coupling order of the modifiers influenced acidification performance, and simultaneous modification (CaO-LFD) was superior to other modes. The highest VFAs production was obtained in CaO-LFD, 51% higher than that in the LFD-first additional modification. The CaO-LFD demonstrated the highest selectivity of acetate production, accounting for 79% of the total VFAs. In addition, CaO-LFD modification changed the direction of the domestication of fermentative bacteria and increased populations of the key anaerobes (Atopostipes sp.) responsible for acidification. The synergistic effect of CaO and LFD was revealed, namely, the effective function of CaO in degrading recalcitrant rice straw, the promotion of transport/metabolism of carbohydrates and acetogenesis by LFD.

Transcriptomic analysis of short-fruit 1 (sf1) reveals new insights into the variation of fruit-related traits in Cucumis sativus.

Fruit size is an important quality trait in different market classes of Cucumis sativus L., an economically important vegetable cultivated worldwide, but the genetic and molecular mechanisms that control fruit size are largely unknown. In this study, we isolated a natural cucumber mutant, short fruit 1 (sf1), caused by a single recessive Mendelian factor, from the North China-type inbred line CNS2. In addition to significantly decreased fruit length, other fruit-related phenotypic variations were also observed in sf1 compared to the wild-type (WT) phenotype, indicating that sf1 might have pleiotropic effects. Microscopic imaging showed that fruit cell size in sf1 was much larger than that in WT, suggesting that the short fruit phenotype in sf1 is caused by decreased cell number. Fine mapping revealed that sf1 was localized to a 174.3 kb region on chromosome 6. Similarly, SNP association analysis of bulked segregant RNA-Seq data showed increased SNP frequency in the same region of chromosome 6. In addition, transcriptomic analysis revealed that sf1 might control fruit length through the fine-tuning of cytokinin and auxin signalling, gibberellin biosynthesis and signal transduction in cucumber fruits. Overall, our results provide important information for further study of fruit length and other fruit-related features in cucumber.