In anther development, tapetal cells take part in complex processes, including endomitosis and apoptosis （programmed cell death）. The tapetum provides many of the proteins, lipids, polysaccharides and other molecules necessary for pollen development. Several transcription factors, including DYT1, TDF1, AMS, MS188 and MS1, have been reported to be essential for tapetum development and function in Arabidopsis thaliana. Here, we present a detailed cytological analysis of knockout mutants for these genes, along with an in situ RNA hybridization experiment and double mutant analysis showing that these transcription factors form a genetic pathway in tapetum development. DYT1, TDF1 and AMS function in early tapetum development, while MS188 and MS1 are important for late tapetum development. The genetic pathway revealed in this work facilitates further investigation of the function and molecular mechanisms of tapetum development in Arabidopsis.
Previous reports indicated that AtMYB103 has an important role in tapetum development,callose dissolution,and exine formation in A.thaliana anthers.Here,we further characterized its function in anther development by expression pattern analysis,transmission electron microscopy observation of the knockout mutant,and microarray analysis of downstream genes.A total of 818 genes differentially expressed between ms188 and the wild-type were identified by global expression profiling analysis.Functional classification showed that loss-of-function of AtMYB103 impairs cell wall modification,lipid metabolic pathways,and signal transduction throughout anther development.RNA in situ hybridization confirmed that transcription factors acting downstream of AtMYB103 (At1g06280 and At1g02040) were expressed in the tapetum and microspores at later stages,suggesting that they might have important roles in microsporogenesis.These results indicated that AtMYB103 is a crucial regulator of Arabidopsis anther development.
