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

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

ACTA PHYSIOLOGIAE PLANTARUM

SPRINGER HEIDELBERG

Año: 2019 vol. 41

0137-5881

Saline and alkaline stresses affect more than 10% of the World?s arable land, limiting agricultural production. Salt-inducedstress may affect the photosystem II (PSII) function, altering fluorescence emission. Therefore, changes in fluorescence 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 NaHCO3in different proportions. Growth, gas exchange, and chlorophyll a fluorescence transient kinetic and OJIPparameters were measured, and chlorophyll a and b were determined. The analysis of the kinetic of chlorophyll a fluorescenceshowed that NaCl-derived stress sources affect the photochemical events in PSII in both ecotypes, being this effect moreevident under higher pH condition, whereas alkalinity per se has a mild or no effect on these events. The saline?alkalinestress induced a more severe effect 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 differential 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.