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 82 631 476 reads consisting of 8 345 779 076 bases. A total of 60 700 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 10 136 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.

Transcriptomic dataset for early inflorescence stages of oil palm in response to defoliation stress

“…1 . and the detail about the research background can be seen in a related research article [1] .

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Carbohydrate deprivation upsurges the expression of genes responsible for programmed cell death in inflorescence tissues of oil palm (Elaeis guineensis Jacq.)

“…The trees were kept under complete defoliation stress for 45 days, after which tissue samples were collected for RNA isolation. It has been estimated that pisifera initiates response mechanisms to stress caused by a halt in the photosynthetic process due to complete defoliation, in the second month after stress treatment (Ajambang et al, 2015b). The trees were felled in the early hours of the day and were cut at the level of their crowns located around leaf number +40.…”

“…The mRNA fragments were converted from 4 µg of total RNA samples prepared into cDNA using the TruSeq v2 RNA Sample Preparation Kit (Illumina Inc., San Diego, CA, USA). Poly-A enrichment was used to obtain mRNA from total RNA as described by Ajambang et al (2015b). The mRNA was purified using poly-T oligolinked magnetic beads in two rounds of purification.…”