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Leaf morphology plays a crucial role in plant classification and provides a significant model for studying plant diversity while directly impacting photosynthetic efficiency. In the case of melons, leaf shape not only influences production and classification but also represents a key genetic trait that requires further exploration. In this study, we utilized forward genetics to pinpoint a recessive locus, dubbed Cmrl (Round leaf), which is responsible for regulating melon leaf shape. Through bulked segregant analysis sequencing and extensive evaluation of a two-year F2 population, we successfully mapped the Cmrl locus to a 537.07 kb region on chromosome 8 of the melon genome. Subsequent genetic fine-mapping efforts, leveraging a larger F2 population encompassing 1322 plants and incorporating F2:3 phenotypic data, further refined the locus to an 80.27 kb interval housing five candidate genes. Promoter analysis and coding sequence cloning confirmed that one of these candidates, MELO3C019152.2 (Cmppr encoding a pentatricopeptide repeat-containing family protein, Cmppr), stands out as a strong candidate gene for the Cmrl locus. Notably, comparisons of Cmrl expressions across various stages of leaf development and different leaf regions suggest a pivotal role of Cmrl in the morphogenesis of melon leaves. [ABSTRACT FROM AUTHOR]

The mechanical properties of various Ti-6Al-4V alloys are influenced by their respective microstructures. This study generated an ultrafine-grain (UFG) Ti-6Al-4V alloy featuring bimodal grain distribution characteristics achieved through initial heat treatment, multi-axial forging (MF), and annealing. The study also extensively examined the evolution process of the alloy's microstructure. By subjecting the materials to heat treatments at 900 °C with air cooling and 950 °C with air cooling, both materials were found to be consisted of primary α (αp) and transformed β (αs+β) regions with different proportions. Following MF, the sample treated at 900 °C displays a microstructure featuring UFGs of α+β surrounding larger micron-sized αp grains. On the other hand, the sample treated at 950 °C displays a microstructure distinguished by twisted αs lamellar and fragmented β grains surrounding larger micron-sized αp grains. Following annealing, no significant grain growth was observed in the sample. The geometrically necessary dislocations (GNDs) within the UFGs were eliminated, though some GNDs persisted within the αp grains. The samples undergoing the 900 °C heat treatment, MF, and subsequent annealing exhibited elevated strength (1280 MPa) and total elongation (10.7%). This investigation introduces a novel method for designing the microstructure of the Ti-6Al-4V alloy to achieve superior performance. [ABSTRACT FROM AUTHOR]

[Objective] This study comprehensively evaluated the drought tolerance of watermelon resources by screening drought tolerant germplasm resources and identifying key drought tolerance indexes at seedling stage to provide support for drought tolerance breeding of watermelon. [Method] Twenty-five watermelon materials were selected for two treatments of drought stress and normal watering in pots at seedling stage. Seven growth indexes including plant height, root length, aboveground fresh weight, underground fresh weight, aboveground dry weight, underground dry weight and root-shoot ratio, and six physiological indexes including chlorophyll content, soluble protein content, proline content, nialondialdehyde con-tent, catalase activity and relative conductivity were measured. Using the methods of membership function, multiple linear regression analysis and cluster analysis, the response differences of watermelon gerniplasm to drought stress were compared, the drought resistance of gerniplasm at seedling stage was evaluated, and the key drought resistance indexes were screened. [Result] Drought stress inhibited the growth and development of watermelon seedlings. Drought stress significantly inhibited shoot fresh mass and root fresh mass of watermelon seedlings, generally reduced plant height, root length, shoot dry mass and root dry mass, and had positive and negative effects on root-shoot ratio. After drought treatment, proline content in watermelon leaves increased significantly, catalase activity increased generally, soluble protein content and relative conductivity in leaves decreased generally, while chlorophyll and nialondialdehyde contents showed differences among germplasms. [Conclusion] The watermelon materials with strong drought resistance at seedling stage including M20, ZTC, M33, M24 and M26, and they can be used for further breeding watermelon resources with drought resistance. Shoot fresh weight, catalase activity, soluble protein content, pro-line content, underground dry weight, and root length could be used as the traits for evaluating drought resistance of watermelon seedlings. [ABSTRACT FROM AUTHOR]

Watermelon is a crucial horticultural crop worldwide but its genetic base has become extremely narrow owing to long-term cultivation. Induced mutagenesis can create a range of variations with distinctive agricultural characteristics. To broaden the genetic diversity of watermelon, we established a mutagenesis library containing over 4000 M1 seeds from an inbred line 'M08', which was irradiated by 350 Gy of 60Co γ-rays for 3 h. The rates of germination, emergence, and survival of the M1 seeds were reduced by 5.88%, 18.66%, and 41.96%, respectively. After phenotypic screening, 20 and 10 types of morphological changes were observed in the M1 and M2 generations, with approximately 10.57% and 14.17% mutation frequencies, respectively. Six mutants with desirable horticultural alterations were selected for additional presentation, including the leaf color mutant C1-NO.1, the yellow peel mutant C1-NO.2, the pericarp thickening mutant C1-NO.3, the pericarp thinning mutant C1-NO.4, the seedless mutant C1-NO.5, and the C2-No.1 mutant with normal female flowers and malformed male flowers. Moreover, the three mutants M1-3, M2-1, and M1-5 were identified from our EMS-induced M2 library, exhibiting the fusiform fruit, the dark green peel, and the yellow leaves, respectively. Compared to the wild type (WT), the photosynthetic pigments and parameters were negatively impacted in the yellow-leaf mutant M1-5. For example, the total chlorophyll was 1.22 and 2.22 mg/g in the young and mature leaves of M1-5, respectively, which were significantly lower than those in the WT (2.58 and 2.90 mg/g, respectively). Notably, some mutagenesis phenotypes could be stably inherited, including traits such as yellow leaf color, fusiform fruit shape, and thickening and thinning pericarp. Taken together, these results indicate that these two mutant libraries serve as essential resources to discover new phenotypic germplasms, thereby facilitating the genetic breeding and functional gene exploration in watermelon. [ABSTRACT FROM AUTHOR]