SPECIFIC DISTRIBUTION OF MESSENGER-RNAS IN MAIZE GROWING POLLEN TUBES OBSERVED BY WHOLE-MOUNT IN-SITU HYBRIDIZATION WITH NONRADIOACTIVE PROBES

The distribution of a number of specific mRNAs has been observed in maize growing pollen tubes. Whole-mount in situ hybridization using digoxygenin-labelled RNA probes has been tested. The technique appears to be a simple, rapid and reliable method in this system, in immature anthers and also in other tissues. Results for three probes are presented. They correspond to a hydroxyproline-rich glycoprotein (HRGP), an abundant component of the maize cell wall, to an alpha-tubulin (encoded by the Tub alpha 1 gene) highly expressed in the radicular system of the plant and also in pollen, and to an isoform of the malic enzyme, involved in the basic metabolism of the plant. The mRNAs corresponding to these three proteins are differently distributed in the germinating pollen. While HRGP mRNA is only present in the tube, malic enzyme mRNA is only present in the body of the pollen cell, and alpha-tubulin mRNA is present in both parts of the cell but shows a higher accumulation in the tip of the pollen tube.