Mutation of the ASHH2 gene has pleiotropic developmental effects. We have focused on the role of ASHH2 in plant reproduction.The aim of the study was to identify changes in gene expression in inflorescences of the ashh2-1/sdg8-1 mutant (SALK_065480, insertion in the gene At1g77300, SDG8/EFS/ASHH2) compared to wt Arabidopsis thaliana (ecotype Colombia) inflorescences. On the female side, close to 80% of mature ovules lack embryo sac. On the male side, anthers frequently develop without pollen sacs or with specific defects in the tapetum layer, resulting in reduction in the number of functional pollen per anther by up to ~90%. ashh2 mutations also result in homeotic changes in floral organ identity. Transcriptional profiling identified more than 300 up-regulated and 600 down-regulated genes in ashh2 mutant inflorescences, whereof the latter included genes involved in determination of floral organ identity, embryo sac and anther/pollen development. This was confirmed by real-time PCR. In the chromatin of such genes (AP1, AtDMC1 and MYB99) we observed a reduction of H3K36 trimethylation (me3), but not H3K4me3 or H3K36me2. Overall design: Five biological replicates with 12 plants each both of Arabidopsis thaliana wild type (ecotype Colombia-0) and ashh2-1/sgd8-1 mutant (SALK_065480, insertion in the gene At1g77300, SDG8/EFS/ASHH2) were sown out on soil and grown under the following conditions; 22oC day and 18oC night, 16 hr day length with 30 min adjustment of light to on and off, and 85 μmol/m2/sek in light intensity. The inflorescences of each biological replikate were harvested in bulk from 30-36 days old plants at same time of the day (between 12:45 and 13:45) and at the same developmental stage in bulk.