Pollen germination genes differentially expressed in different pollens from Dura, Pisifera and Tenera oil palm (Elaeis guineensis jacq.)

Oil palm (Elaeis guineensis jacq.) is considered as the king of world's oil crops because it is the highest oil producing crop in the world. Pollination is perfectly important to increase fruits and yield because it is the first step in fruit development process. However, very few limited publications are available on the study of oil palm pollen. In this study, Elaeis guineensis importin subunit beta-1-like, mRNA sequence (XP_010939614.2, 3314 bp in length) which showed 76% identity to rice pollen-expressed gene (rice Importin β1), importin subunit beta-1, was downloaded to study the gene expression pattern of oil palm pollen. For gene expression analysis with real time quantitative PCR, the accuracy of the determination of target gene expression depends on the use of reliable reference gene. In order to identify suitable reference gene, we selected the most commonly used reference genes (Act, Apt, cyc and eIF) and ranked their expression stabilities using two statistical algorithms; geNorm and NormFinder. The results from both algorithms showed that Act was the most stable gene for oil palm pollen germination gene. Expression analysis of oil palm pollen gene in three different fruit forms showed that the expression levels of pollen gene in Dura and Tenera fruit forms were down-regulated after germination while up-regulation was observed in Pisifera. This research will be useful in future molecular genetics resource studies of gene expression in pollen germination of oil palm.