Background
During anther development, the tapetum provides essential nutrients and materials for pollen development. In rice, multiple transcription factors and enzymes essential for tapetum development and pollen wall formation have been cloned from male-sterile lines.
Results
In this study, we obtained several lines in which the MYB transcription factor OsMS188 was knocked out through the CRISPR-Cas9 approach. The osms188 lines exhibited a male-sterile phenotype with aberrant development and degeneration of tapetal cells, absence of the sexine layer and defective anther cuticles. CYP703A3, CYP704B2, OsPKS1, OsPKS2, DPW and ABCG15 are sporopollenin synthesis and transport-related genes in rice. Plants with mutations in these genes are male sterile, with a defective sexine layer and anther cuticle. Further biochemical assays demonstrated that OsMS188 binds directly to the promoters of these genes to regulate their expression. UDT1, OsTDF1, TDR, bHLH142 and EAT1 are upstream regulators of rice tapetum development. Electrophoretic mobility shift assays (EMSAs) and activation assays revealed that TDR directly regulates OsMS188 expression. Additionally, protein interaction assays indicated that TDR interacts with OsMS188 to regulate downstream gene expression.
Conclusion
Overall, OsMS188 is a key regulator of tapetum development and pollen wall formation. The gene regulatory network established in this work may facilitate future investigations of fertility regulation in rice and in other crop species.
In this study, the tour planning problem for electric vehicles is investigated. We aim to derive the optimal route and thus, to maximize profitability and minimize range anxiety within the time horizon. To solve this problem, a bi-objective mixed integer model is proposed. Specifically, we first introduced the reliability of route planning and quantified it as a cost with specific functions. The nonlinear model was then converted into a bi-objective mixed integer linear program, and an interactive branch and bound algorithm was adopted. Numerical experiments conducted on different networks have shown that the model that considers range anxiety offers more effective solutions. This means that our model is able to plan the routes with high reliability and low risk of profit loss and accidents.
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