The Role of the Expansin Gene in the Process of Novel Subterranean Seed Development in Arachis duranensis

Background: Plants in the genus Arachis produce flowers aerially that develop into gynophores that grow into the ground, where they develop into fruits. Although some aerial gynophores develop into pods aboveground, embryo or seed abortion occurs in these individuals. During pod development, the shell wall initially comprises the majority of the fruit volume, but then the seeds expand up to the total pod volume. Expansins are plant cell wall-loosening proteins involved in cell enlargement and a variety of other developmental processes in which cell-wall modification occurs.Methods: In this study, we analyzed the expansin genes during seed development using RNA-seq data by bioinformatic approaches.Results: We identified five expansin genes exhibited up-regulated expression, while four genes were down-regulated expression using Arachis duranensis RAN-seq data. Multiple transcription factors regulate AdEXPs throughout seed development. Genes co-expressed with AdEXPs are involved in metabolic processes throughout pod development into seed development, reframing the current understanding of the novel subterranean peanut fruits.