High-throughput micro-phenotyping measurements applied to assess stalk lodging in maize ( Zea mays L. )

BACKGROUND: The biomechanical properties of maize stalks largely determine their lodging resistance, which affects crop yield per unit area. However, the quantitative and qualitative relationship between micro-phenotypes and the biomechanics of maize stalks is still under examined. In particular, the roles of the number, geometry, and distribution of vascular bundles of stalks in maize lodging resistance remain unclear. Research on these biomechanical properties will benefit from high-resolution micro-phenotypic image acquisition capabilities, which have been improved by modern X-ray imaging devices such as micro-CT and the development of micro-phenotyping analysis software. Hence, high-throughput image analysis and accurate quantification of anatomical phenotypes of stalks are necessary. RESULTS: We have updated VesselParser version 1.0 to version 2.0 and have improved its performance, accuracy, and computation strategies. Anatomical characteristics of the second and third stalk internodes of the cultivars 'Jingke968' and 'Jingdan38' were analyzed using VesselParser 2.0. The relationships between lodging resistance and anatomical phenotypes of stalks between the two different maize varieties were investigated. The total area of vascular bundles in the peripheral layer, auxiliary axis diameter, and total area of vascular bundles were revealed to have the highest correlation with mechanical properties, and anatomical phenotypes of maize stalk were better predictors of mechanical properties than macro features observed optically from direct measurement, such as diameter and perimeter. CONCLUSIONS: This study demonstrates the utility of VesselParser 2.0 in assessing stalk mechanical properties. The combination of anatomical phenotypes and mechanical behavior research provides unique insights into the problem of stalk lodging, showing that micro phenotypes of vascular bundles are good predictors of maize stalk mechanical properties that may be important indices for the evaluation and identification of the biomechanical properties to improve lodging resistance of future maize varieties.

Study of the dynamic expression of Meis1 in mice

Background: aggressive embryo and receptive endometrium are necessary for successful implantation. On this time endometrium transformates to receptive state, which permits embryonic implantation. Studies about embryonic implantation and endometrial receptivity are always a hot spot in the field of reproductive medicine

Objective: to investigate the expression pattern of Meis1 during peri-implantation in mice endometrium

Materials and Methods: mice for experiment were raised in SPF environment. The mice were mated with a female/male ratio of 2:1. The female mice with detected plugs were regarded as pregnant day 1 [pd1]. Endometrial tissues were collected respectively on pd1, pd2, pd4, pd5 and pd6. Immunohistochemistry was used to detect the location of Meis1 in mice endometrium. The expression level of mRNA and protein of Meis1 were further detected using Quantitative PCR and Western blotting, respectively

Results: we found that Meis1 is located in the cytoplasm and membrane of endometrial glandule epithelium cells and the nucleus of endometrial stromal and decidual cells. Both Quantitative RT-PCR and western blotting showed that Meis1 expressed regularly in mice endometrium. Meis1 mRNA expressed weakly on pd1, then significantly increased on pd4 [p=0.018], and achieved to a peak on pd5 [p=0.0012], it showed a decrease trend on pd6. Meis1 protein expressed weakly on pd1 and pd2, then significantly increased on pd4 and pd5 [p=0.0019], it showed a decrease trend on pd6

Conclusion: meis1 is dynamically expressed in mice endometrium during peri-implantation. The time that Meis1 expression reaches its peak value is coincident with the implantation window, which implied that Meis1 is closely related with embryonic implantation