Genomic approaches based on high throughput sequencing recently defined changes in transcriptome at an unprecedented depth, including antisense and intergenic transcription, alternative splicing events and mRNA processing.
One of the major discoveries linked to these large scale approaches was that the number of non-protein-coding transcripts (or npcRNAs) is much larger than previously believed, including microRNAs, small-interfering siRNAs and high numbers of long npcRNAs or lincRNAs.
As npcRNAs can act as positive or negative regulators of gene expression, we can speculate that the non-coding portion of the genome, rather than the protein coding genes, may be act as a major force in evolution and ecotype adaptation.
Thus, in addition to promoters or other DNA regions, non-coding RNAs are emerging actors in the adaptation of plants to environmental constraints.
Root development is a complex process integrating a large variety of endogenous signaling pathways and exogenous cues (e.g. nutrients or soil water content).
The organisation of a primary root follows a reiterative developmental pattern with defined cell types produced by the root apical meristem.
However, environmental cues affect the function of this meristem and induce changes in root growth and architecture both at cellular and organ levels. Modifying spatially or temporally the action of miRNAs or other regulatory lncRNAs maybe one way for plants to integrate signals from the environment into developmental and growth programs.
This plasticity, a fundamental feature of plant growth, provides the immobile plant with the ability to cope with environmental stresses.
Another model of root plasticity in response to environmental constraints is the ability of legume plants, under low nitrogen conditions, to interact with bacterial symbionts to develop new organs, the nitrogen-fixing nodules.
Arabidopsis is unable to perform such symbiotic interaction and Medicago truncatula is one model legume currently studied in many labs worldwide.