Comparative expression profiling of three early inflorescence stages of oil palm indicates that vegetative to reproductive phase transition of meristem is regulated by sugar balance.

Abstract

Breeding and seed production activities in oil palm have been hampered because of the inability of the male parent Pisifera to produce male inflorescence as source of pollen under normal conditions. Researchers are using complete defoliation to induce male inflorescences, but the biological and molecular processes responsible for this morphological change are yet to be revealed. To understand the underlying network of genes that initiate and control this phenotypically documented activity, we initiated a study aimed at identifying differentially expressed genes (DEGs) in three stages of an oil palm inflorescence under complete defoliation stress using RNA-seq. Sequencing on an Illumina platform produced 82631476 reads consisting of 8345779076 bases. A total of 60700 genes were obtained after transcript filtering and normalisation and 54% of them were downregulated. Differences in gene expression levels were significant between tissues under stress. The farther the distance between tissues, the more DEGs recorded. Comparison between stage 2 and stage 1 induced 3893 DEGs whereas 10136 DEGs were induced between stage 3 and stage 1. Stress response genes and flower development genes were among the highly expressed genes. This study suggests a link between complete defoliation and meristem differentiation from vegetative to reproductive phase in oil palm.