A Non-Shedding Fruit Elaeis oleifera Palm Reveals Perturbations to Hormone Signaling, ROS Homeostasis, and Hemicellulose Metabolism

Fabienne Morcillo,Simon George,Antoine Beckers,Roberto Poveda,Sebastien Tisné,Claude Louise,Timothy John Tranbarger,Myriam Collin,Julien Serret

doi:10.3390/genes12111724

Abstract

The developmentally programmed loss of a plant organ is called abscission. This process is characterized by the ultimate separation of adjacent cells in the abscission zone (AZ). The discovery of an American oil palm (Elaeis oleifera) variant that does not shed its has allowed for the study of the mechanisms of ripe fruit abscission in this species. A comparative transcriptome analysis was performed to compare the fruit AZs of the non-shedding E. oleifera variant to an individual of the same progeny that sheds its ripe fruit normally. The study provides evidence for widespread perturbation to gene expression in the AZ of the non-shedding variant, compared to the normal fruit-shedding control, and offers insight into abscission-related functions. Beyond the genes with known or suspected roles during organ abscission or indehiscence that were identified, a list of genes with hormone-related functions, including ethylene, jasmonic acid, abscisic acid, cytokinin and salicylic acid, in addition to reactive oxygen species (ROS) metabolism, transcriptional responses and signaling pathways, was compiled. The results also allowed a comparison between the ripe fruit abscission processes of the African and American oil palm species at the molecular level and revealed commonalities with environmental stress pathways.

Highlights

Fruit abscission is a developmentally regulated process that facilitates seed dispersal of plant species and an agronomically important character and domestication trait for crop species [1,2]
While we have previously examined in great detail the ripe fruit abscission processes at the molecular and cellular levels in the multilayer abscission zone (AZ) of the African oil palm [7,8,9,10,11], very little is known about the molecular processes of abscission in E. oleifera and how the abscission processes have diverged between these two closely related species separated by millions of years of evolution
Fruit bunches from another individual within the same TA59D genetic background was identified with a high Abscission Index (AI) and with fruit that separate from the fruit bunch and found at the base of the palm, indicating fruit abscission and shedding occurred and is a normal sheds its fruit normally (Sd) character

Summary

Introduction

Fruit abscission is a developmentally regulated process that facilitates seed dispersal of plant species and an agronomically important character and domestication trait for crop species [1,2]. There are two species of oil palm, Elaeis guineensis from Africa and Elaeis oleifera from South and Central America, which diverged from each other approximately 7–16 million years ago [3,4]. We previously found differences in the abscission zone (AZ) anatomy between E. guineensis and E. oleifera [6]. While we have previously examined in great detail the ripe fruit abscission processes at the molecular and cellular levels in the multilayer AZ of the African oil palm [7,8,9,10,11], very little is known about the molecular processes of abscission in E. oleifera and how the abscission processes have diverged between these two closely related species separated by millions of years of evolution

Methods

Results

Discussion

Conclusion