Abiotic Stress Responses in Plants: Unraveling the Complexity of Genes and Networks to Survive - Abiotic Stress: Plant Responses and Applications in Agriculture - page 76

Several stress-resistant genes encoding for functional proteins were identified and intro‐
duced via genetic engineering into model species such as Medicago truncatula , Nicotiana
tabacum or Arabidopsis thaliana , producing plants with improved abiotic stress tolerance.
These results support the future use of this technology into economically important
plants species namely crops and trees. As a consequence of the novel findings on the
mechanisms underlying the regulation of gene expression under abiotic stress, we could
speculate that future genetic engineering approaches might be targeted to these regulato‐
ry pathways. Emerging reports where the expression of regulatory molecules such as
transcription factors (e.g. NAC proteins) or components of the small RNA pathway (e.g.
miR398) are described to successfully produce abiotic stress resistant plants, supporting
our hypothesis. Nevertheless, it should be kept in mind that the success of this approach
relies on the development of efficient regeneration and transformation methods adequate
to the target species or genotype. Future research efforts should be directed to overcome
this significant limitation. Although the use of a constitutive promoter (e.g. CaMV 35S)
ensured the expression of the target coding sequence, it presents some disadvantages as
discussed previously. The use of inducible promoters (e.g. rd29A) that allow the expres‐
sion of a transgene only when it is required could therefore be the ideal solution.
As stated previously across this manuscript, the nature and complexity of abiotic stress
responses supports the use of global, integrative and multidisplinary approaches to under‐
stand the different levels of regulation of stress responses. The emerging holistic System
Biology approaches still enclose a myriad of unexploited resources for Plant and Agricultural
Sciences. Given the increasing development of high throughput genomic tools and concomi‐
tant release and progress on plants genome sequencing, it is now possible to gain information
in a global scale, providing an overall comprehensive and quantitative overview on the gene-
to-metabolite network associated to a particular plant response. The use of such cutting-edge
methodologies to a specific plant species requires a previous study of the availability of
reference genomes (e.g. Phytozome [314]), metabolite (e.g. Plant Metabolic Network [315]) or
proteomic databases (e.g. UniProtKB [316]). Additionally, it requires appropriate laboratory,
equipment and bioinformatics facilities and know-how that can be accessed using own
institutional infrastructures or taking advantage of established collaborations with renowned
research institutional research platforms and /or commercial service providers.
Presently, we are exploring the molecular mechanisms underlying Medicago truncatula and
Phaseolus vulgaris adaptation to water deprivation using a System Biology approach that
combines whole plant physiology data with transcriptomics, proteomics and metabolomics.
We aim to identify candidate genes to be used in legume improvement programs and also
fundamental knowledge on points of transcriptional, post-transcriptional and post-transla‐
tional regulation of the gene expression under stress in these species. This highlights the efforts
that we are currently doing to transfer the developed tools and information gained with the
model Medicago truncatula to an important grain legume crop. A robust identification of the
molecular targets to be used in biotechnological applications will be elucidated. Additionally,
some clues about the signaling, regulation and interaction between the different cellular
players involved are also expected.