Agriculture Reference
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ELIP-like proteins are thought to protect the chloroplast apparatus from photooxidation by:
a) acting as transient pigment-binding proteins during biogenesis or turnover of chlorophyll
binding proteins [262, 266, 268, 272]; b) binding or stabilising carotenoids like zeaxantin and
lutein [266, 268, 273, 274]; c) stabilising the pigment-protein complexes and/or favouring their
appropriate assembly [268, 272, 274, 275]; d) dissipating the excessive absorved light energy
at the reaction center of the PSII, in the form of heat or fluorescence [276].
We decided to express the dsp22 gene from Craterostigma plantagineum [258] in M. truncatula ,
aiming to investigate the protective role of this ELIP-like protein in the photosynthetic
apparatus, during the dehydration and rehydration [81, 241]. We assessed the photochemical
performance of in dsp22 transgenic (A.27) and wild type (M9-10a) plants together with leaf
pigment contents and biomass accumulation during dehydration and subsequent recovery.
Transgenic M. truncatula plants overexpressing the ELIP-like DSP22 protein display higher
amount of chlorophyll (Chl), lower Chl a /Chl b ratio and higher actual efficiency of energy
conversion in PSII after dehydration and rehydration, also suggesting a role in pigments
stabilization during WD stress [81]. Our results are in agreement with the transient photosyn‐
thetic pigment binding function postulated for ELIPs and ELIP-like proteins under disturbing
environmental conditions [266, 268]. Additionally, the results indicate that DSP22 may
contribute to reduce the impact of photooxidative damage on the PSII complex of M. trunca‐
tula resulting from WD and recovery treatments. Despite of this assumption, the mechanisms
by which DSP22 leads to enhanced photooxidative protection in this model legume are yet not
clear and further studies are necessary to support these hypothesis. Nevertheless, the results
supports that the expression of photoprotective proteins, such as ELIPs, can be considered a
valuable approach to improve abiotic stress resistance in crops.
5. Omics and system biology approaches to understand abiotic stress
responses
During the last decade, the “reductionistic” molecular biology and functional biology ap‐
proaches are being progressively replaced by the “holistic” approach of systems biology.
However, molecular biology and systems biology are actually interdependent and comple‐
mentary ways in which to study and make sense of complex phenomena [277]. Presently, the
use and development of post-genome methodologies, such as global analysis of transcrip‐
tomes, proteomes and metabolomes integrated in solid bioinformatics platforms, has notice‐
ably changed our knowledge and holistic understanding various plants function, including
the response to abiotic stresses [278]. System-based analysis can involve multiple levels of
complexity, ranging from single organelles or cells, tissues, organs to whole organisms. These
variables can be still combined with multiple developmental stages and environmental
interactions suggesting an infinite number of permutations to this complexity [279].
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