Sequence characterization and expression anaysis of peanut (Arachis hypogaea L.) lncRNA Enod40 (AhEnod40)

JOHAN STIBEN RODRIGUEZ MELO; ZE PENG; JIANPING WANG; FEDERICO ARIEL; LEANDRO LUCERO; MARIA LAURA TONELLI; ADRIANA FABRA; FERNANDO IBAÑEZ

Buenos Aires

Workshop; Biología Celular y Molecular del ARN; 2018

Peanut (Arachis hypogaea L.) is an important legume crop worldwide. It is an allotetraploid species (2n=4x=40, AABB genome type; about 2.8 Gb with a high repetitive DNA content) probably derived from a single hybridization event of two wild species, A. ipaënsis and A. duranensis (2n=20). The complexity of cultivated peanut genome has hindered its sequencing. Therefore, only the genomic sequence of the wild peanut ancestors was available in databases until very recently. As a legume, peanut is able to interact with bradyrhizobia in a nitrogen-fixing symbiosis. In peanut, symbiotic development occurs through a primitive and poorly characterized aeschynomenoid program. Relatively little is known about the molecules implicated in this symbiotic process. Enod40 is a classic early nodulin reported as essential for nodulation in several legumes. This long non-coding RNA (lncRNA) has an unusual structure, since it lacks a long open reading frame (ORF). However, short ORFs are present (Sousa et al., 2001) in Enod40 transcripts, coding for two peptides apparently linked to its biological activity. Due to the highly structured RNA, it has been suggested that the Enod40 activity resides in the RNA (Crespi et al., 1994; Sousa et al., 2001; Girard et al., 2003). It has also been reported that Enod40 participates in the nucleocytoplasmic trafficking of RBP1 and in RBP1-dependent splicing modulation ( Crespi et al., 1994; Campalans et al., 2004; Romero-Barrios et al., 2018). In a previous work (Peng et al., 2017), regions XLOC_021512 and XLOC_058301 were identified as upregulated in four nod+ peanut lines tested during the establishment of N-fixing symbiosis (5 dpi). However, these chromosomic regions were not further characterized. In this work, we provide evidence that these regions encode for Enod40 and analyse the transcript folding predictions and expression patterns during early time points of symbiotic development.