ACCUMULATION OF SPECIFIC MESSENGER-RNAS DURING ALMOND FRUIT-DEVELOPMENT

The mRNA accumulation of a number of different genes during different stages of almond fruit development has been studied. The probes used i n the study correspond to almond cDNAs previously characterized in our laboratory. They include cDNAs encoding extensin, prunin (the main st orage protein in almond seed), oleosin, alpha-tubulin and a cDNA clone (PA3BF11) not showing any similarity to known sequences but whose mRN A is very abundant in the almond seed. These probes have been used in RNA blot, tissue printing and in situ hybridization experiments, The t issue printing technique has proven to be a very useful tool for detec ting gene expression in large organs such as whole almond fruits where as in situ hybridization can be successfully applied in small fruits. It is shown that the distribution of specific mRNAs is highly controll ed in the fruit. mRNAs related to storage proteins are abundant in see d tissues while mRNAs corresponding to genes related to cell division; such as extensin or alpha-tubulin, are accumulated in dividing cells mostly around the vascular tissues.