Inter-kingdom complementation discloses functional convergence of lipocalins

Patricia Henri (1, 2) , Dominique Rumeau (1, 2)

1 BIAM - Institut de Biosciences et Biotechnologies d'Aix-Marseille (ex-IBEB)
2 PPV - Protéines de Protection des Végétaux

Abstract Background The chloroplastic lipocalin (LCNP) is induced in response to various abiotic stresses including high light, dehydration and low temperature. It contributes to protection against oxidative damage promoted by harmful conditions by preventing accumulation of hydroxy fatty acids and lipid peroxidation. In contrast to animal lipocalins, LCNP is poorly characterized and the molecular mechanism by which it exerts protective effects during oxidative stress is largely unknown. LCNP is considered the ortholog of human apolipoprotein D (APOD), a protein whose lipid antioxidant function has been characterized. Here, we investigated whether APOD could functionally replace LCNP in Arabidopsis. Results We introduced APOD cDNA fused to a chloroplast transit peptide encoding sequence in an Arabidopsis LCNP KO (knock-out) mutant line and challenged the transgenic plants with different abiotic stresses. We demonstrated that expression of human APOD in Arabidopsis can partially compensate for the lack of the plastid lipocalin. However, if the results obtained with the drought and oxidative stresses point to the protective effect of constitutive expression of APOD in plants lacking LCNP, this effect is not as effective as that conferred by LCNP overexpression. Moreover, when investigating APOD function in thylakoids after high light stress at low temperature, it appeared that APOD could not contribute to qH, a slowly reversible form of non-photochemical chlorophyll fluorescence quenching, as described for LCNP. Conclusions The results are consistent with a conserved function of APOD and LCNP under stressful conditions. The work contributes towards understanding the molecular mechanism of action of LCNP in oxidative stress protection and provides the basis for new research assumptions.

Domaines: Amélioration des plantes

Patricia Henri, Dominique Rumeau. Inter-kingdom complementation discloses functional convergence of lipocalins. BMC Plant Biology, In press. ⟨hal-02276224⟩