Phytohormonal responses in enod40‐overexpressing plants of Medicago truncatula and rice

Abstract

Phytohormones are well-known regulators of the symbiotic Rhizobium-legume association in the plant host. The enod40 nodulin gene is associated with the earliest phases of the nodule organogenesis programme in the legume host and modifying its expression resulted in perturbations of nodule development in Medicago truncatula. Therefore in our pursuit to mimic the initial signal transduction steps of legume nodulation in the alien physiological set-up of a rice plant, we have expressed the Mtenod40 gene in rice. Molecular data confirm the stable integration, inheritance and transcription of the foreign gene in this non-legume. We have compared the phytohormonal responses of Mtenod40-overexpressing and control plants in a homologous legume background (M. truncatula) and in the non-legume rice. An enod40-mediated root growth response, induced by inhibition of ethylene biosynthesis, was observed in both plants. On the other hand, a significant differential effect of cytokinins was observed only in rice plants. This suggests that ethylene inhibits enod40 action both in legumes and non-legumes and reinforces that some of the early signal transduction steps of the nodule developmental programme may function in rice.

Long noncoding RNA transcriptome of plants

“…The enod40 RNA of M. truncatula encodes only a short open reading frame and it colocalizes with RNA‐Binding Protein 1 (MtRBP1). During nodule development, MtRBP1 together with enod40 translocates from nuclear speckles to the cytosol in root cells, whereas in the cells without expressed enod40, MtRBP1 is retained in the nucleus (Campalans et al ., ; Dey et al ., ). It will be interesting to clarify the biological significance of this observation in future.…”

The Arabidopsis Mei2 homologue AML1 binds AtRaptor1B, the plant homologue of a major regulator of eukaryotic cell growth

“…There is a fairly large population of mRNA-like transcripts conserved among land plants despite lacking large conserved open reading frames [29]. Of these, the conserved alfalfa transcript ENOD40 has been shown to mediate the sub-cellular localization of an RNA-binding protein [30] and to mediate phytohormone responses [31]. AML1 may be a binding partner of one or more of these mRNA-like noncoding molecules in plants.…”

New technologies accelerate the exploration of non-coding RNAs in horticultural plants

“…The molecular mechanisms underlying the biological function of plant lncRNAs include: (1) processing into shorter ncRNAs for functioning, 38 (2) acting as the target mimics of miRNAs, 39,40 (3) repressing histone-modifying activities and direct epigenetic silencing via interaction with specific chromatin domains, 41,42,43,44 (4) acting as molecular cargo for protein re-localization 45,46 and (5) post-translational regulation through protein modification and protein–protein interactions. 6 …”