Transcriptome‐wide sequencing provides insights into geocarpy in peanut (Arachis hypogaea L.)

Abstract

Summary A characteristic feature of peanut is the subterranean fructification, geocarpy, in which the gynophore (‘peg’), a specialized organ that transitions from upward growth habit to downward outgrowth upon fertilization, drives the developing pod into the soil for subsequent development underground. As a step towards understanding this phenomenon, we explore the developmental dynamics of the peanut pod transcriptome at 11 successive stages. We identified 110 217 transcripts across developmental stages and quantified their abundance along a pod developmental gradient in pod wall. We found that the majority of transcripts were differentially expressed along the developmental gradient as well as identified temporal programs of gene expression, including hundreds of transcription factors. Thought to be an adaptation to particularly harsh subterranean environments, both up‐ and down‐regulated gene sets in pod wall were enriched for response to a broad array of stimuli, like gravity, light and subterranean environmental factors. We also identified hundreds of transcripts associated with gravitropism and photomorphogenesis, which may be involved in the geocarpy. Collectively, this study forms a transcriptional baseline for geocarpy in peanut as well as provides a considerable body of evidence that transcriptional regulation in peanut aerial and subterranean fruits is complex.

Development of chloroplast genome resources for peanut (Arachis hypogaea L.) and other species of Arachis

“…Next generation sequencing (NGS) methods have enabled the rapid and cost-efficient sequencing of plant genomes. In past several years, several studies have reported the development of genetic resources for peanut, including SSRs 14 , 27 , transcript sequences 28 , 29 , and draft nuclear genome sequences 1 , 3 . However, the chloroplast genome is non-recombining and uniparentally inherited, making it a valuable source of information for improving the phylogenetics, species identification, and resolution 18 , 30 , 31 .…”

A Developmental Transcriptome Map for Allotetraploid Arachis hypogaea

“…Geocarpy is a fascinating aspect of Arachis reproductive development. There have been studies investigating the gene expression during geocarpic development in peanut (Xia et al, 2013 ; Zhu et al, 2014 ; Chen et al, 2016 ). Zhu et al ( 2014 ) and Xia et al ( 2013 ) identified an up-regulation of photosynthesis in aerial pegs.…”

Defining the function of SUMO system in pod development and abiotic stresses in Peanut

“…The gravitropic growth of the peanut gynophore is one of the most critical characteristics for peanut fructification, in which the peg, a specialized organ that transitions from upward growth habit to downward outgrowth upon fertilization, drives the developing pod into the soil for subsequent development underground [37,61,62]. It is still unknown why the aerially developing pod cannot swell normally as compared to that penetrate into soil, although a series of studies attempt to reveal this phenomenon through transcriptomics and proteomics [37,61,63]. Our results found that there was no significant difference in the expression level of SUMO pathway genes between the aerial peg stage and the subterranean peg stage.…”

“…Then, the pod develops and a mature peanut pod is produced [35,36]. The subterranean fructification is the most prominent characteristic of seed production in peanut and thus has the biologically important for studying organogenesis and evolution [37]. Additionally, peanut often cultivated in the semiarid tropical regions, are often exposed to water stress (mid-season and end-season) and high temperature (> 34°C) during the critical stages of flowering and pod development [38].…”