Chloroplast proteomics reveals new insights into the low temperature stress acclimation of the model legume Lotus japonicus

CALZADILLA P.I; VILAS, JUAN MANUEL; ESCARAY F J; CARRASCO P; RUIZ O.A.

Barcelona

Congreso; XXII Reunion de la Sociedad Espanola de Fisiologia Vegetal; 2017

Sociedad Espanola de Fisiologia Vegetal

Low temperature is one of the most important factors affecting plant growth, directly altering thephotosynthetic process and leading to photo-inhibition. With the aim to address the photosyntheticacclimation response of L. japonicus under cold stress, two ecotypes (MG-1 and MG-20) were studied.Previous data showed that photo-inhibition occurs in stress and differentially between ecotypes, being MG1 more affected than MG-20. Futhermore, a chloroplastic redox imbalance was generated due to lowtemperature, but only in the sensitive ecotype.In this study, we used a proteomic approach to evaluate changes in the chloroplast proteome of both MG1 and MG-20 ecotypes after 7 d of low temperature and control treatments. A total of 724 proteins wereidentified, of which 12 presented significative interaction between ecotypes and temperature treatments,66 were differentially abundant between ecotypes and 64 between temperature treatments. Functionalannotation and classification were performed using KEGG, Uniprot and LegumeIP databases, as well asthe STRING software. A greater abundance of proteins related with photosynthesis ?light-reactions? (inparticular, oxidative phosphorilation and antenna proteins) were identified in the MG-1 ecotype comparedto the MG-20. By the contrary, in MG-20, proteins related with the carbon metabolism, the oxidative stressresponse and protein folding were more abundant.Changes in the photosynthetic and carbon metabolisms suggested two different acclimation strategies inthe L. japonicus chloroplasts studied. While in the sensitive MG-1 ecotype those mechanisms seem to beimplicated with energy dissipation in photosystems, regulation of the source/sink carbon ratio seems to bepreponderant in the tolerant MG-20. Data showed that the differential response of both L. japonicusecotypes to cold stress could be, at least partially, explained by these different acclimation strategies. As aconclusion, our results emphasized the relevance of the carbon metabolism in the low temperatureacclimation of the model legume L. japonicus.