Regulation of pollen development
The control of plant reproduction has a high priority in agriculture and so an understanding of the biological mechanisms underlying pollen development is essential. We have identified and studied two genes in Arabidopsis thaliana whose expression is essential for pollen development. Both genes code for transcription factors, proteins that regulate the expression of other genes. The two transcription factors belong to the MYB family of regulatory proteins. Both are developmentally regulated, being turned on and off at specific stages of anther development. They are strongly expressed in the tapetum, a tissue of the anther that provides nutrition and structural components to the developing pollen grain.
We are using insertion mutants to ascertain which genes and metabolic pathways are regulated by the two MYB proteins. One protein appears to be involved in flavonoid synthesis and the other in controlling cell division in the anther. Two-hybrid analysis is being used to identify proteins with which the MYB proteins interact when regulating gene expression.
A gene coding for a small, cysteine-rich protein which is specifically expressed in the tapetum has been identified. This protein is probably secreted from the cell and may form part of the pollen coat. Its regulation and function are being studied. The protein may be involved in disease resistance.
Our knowledge of pollen development has been used to devise a system of reversible male sterility that can be used for hybrid seed production.