Determination and expression of miRNAs during development of female and male organs in the infloresecence buds of Pistachio

The great majority of flowering plants are hermaphrodites, while only a few of them contain dioecious species having separate male and female plants. Pistachio (Pistacia vera L.) is a dioecious species and wind is pollinating agent. In this study, it was aimed to investigate the growth of sex organs in female and male inflorescence buds of pistachios by scanning electron microscopy (SEM) and to identify differentially expressed sex related miRNAs and their targeted genes during the bud development by small RNA (sRNA) sequencing. For SEM analyzes and sRNA sequencing, the buds were sampled weekly from the beginning of the development of flower buds in spring to until the next year before flowering. As a result of the SEM analysis, it was determined that both sexes were formed in the first stages of the development of both male and female inflorescence buds in the spring, while the opposite sex organ development was stopped after at the end of June. sRNA sequencing was performed in the samples collected in 10 periods covering the first stages of bud development in the spring and three periods before flowering. As a result of sRNA sequencing, known miRNAs changed from 159 to 181 and novel miRNAs were between 289 and 360 in female samples, while known miRNAs ranged from 134 to 174 and novel miRNAs were between 224 and 335 in male samples. A total of 25 differentially expressed miRNAs were identified between female and male samples: 18 of them were highly expressed in females while seven of them were highly expressed in males, and were validated by qRT-PCR. Eleven of differentially expressed miRNAs targeted 78 genes in female Siirt genome and 157 genes in male Bağyolu genome. It was determined that some of the targeted genes are responsible for the development of flower organs in different plant species.