Chlorophyll a fluorescence analysis reveals divergent photosystem II responses to saline, alkaline and saline–alkaline stresses in the two Lotus japonicus model ecotypes MG20 and Gifu-129

BORDENAVE, CÉSAR DANIEL; ROCCO, RUBÉN; MAIALE, SANTIAGO JAVIER; CAMPESTRE, MARIA PAULA; RUIZ, OSCAR ADOLFO; RODRÍGUEZ, ANDRÉS ALBERTO; MENÉNDEZ, ANA BERNARDINA

ACTA PHYSIOLOGIAE PLANTARUM

SPRINGER HEIDELBERG

Año: 2019 vol. 41

0137-5881

Saline and alkaline stresses afect more than 10% of the World?s arable land, limiting agricultural production. Salt-inducedstress may afect the photosystem II (PSII) function, altering fuorescence emission. Therefore, changes in fuorescence areused to quantify and analyze abiotic stress responses in plants. So far, no study has focused on the response of PSII to saline,alkaline and saline?alkaline stresses in the model legume Lotus japonicus. For the saline, alkaline and saline?alkaline treatments, plants of the L. japonicus ecotypes MG20 and Gifu-129 were cultivated in sand with nutrient solution, added withNaCl and NaHCO3 in diferent proportions. Growth, gas exchange, and chlorophyll a fuorescence transient kinetic and OJIPparameters were measured, and chlorophyll a and b were determined. The analysis of the kinetic of chlorophyll a fuorescenceshowed that NaCl-derived stress sources afect the photochemical events in PSII in both ecotypes, being this efect moreevident under higher pH condition, whereas alkalinity per se has a mild or no efect on these events. The saline?alkalinestress induced a more severe efect on Gifu B-129, compared with Miyakojima MG20, whereas NaCl improved primaryphotochemistry in MG20. Our results allow us to accept the hypothesis that both ecotypes deploy diferential responsesunder the three stressful treatments and that the saline?alkaline stress causes higher damage levels than saline and alkalinestresses alone in relation with structures and sub-processes of the PSII.