Salt overly sensitive 1 (SOS1) gene expression can be regulated via Azospirillum brasilense Sp7 in wheat seedlings under saline condition | Izražanje na sol preobčutljivega gena (SOS1) bi pri pšenici v razmerah slanosti lahko uravnavali s sevom bakterije Azospirillum brasilense Sp7

anglais. Salinity stress reduces plant growth via failure of physiological processes mainly due to the abundance of Na+ ion. Salt overly sensitive (SOS) signaling pathway is considered as an important component of Na+/K+ homeostasis system in plants, especially under saline condition. Moreover, it is reported that wheat-Azospirillum associated has resulted in an enhanced salinity tolerance. To evaluate involvement of Azospirillum species in regulation of SOS signaling pathway, inoculated and none-inoculated wheat seedlings with Azospirillum brasilense Sp7 were grown for five days. Then uniform seedlings were transferred into saline hydroponic media with and without 200 mM NaCl. The relative expression of TaSOS1 of root, sheath, and blade as well as Na+/K+ ratio was measured after 6, 24 and 48 hours since inoculated and non-inoculated seedling were transferred to NaCl media. Simultaneously Ca, Fe, proline content, root and shoot dry mass and soluble sugars were measured at 72 hour after application of NaCl. Result showed that salinity increased TaSOS1 gene expression, Na+, prolin and Na+/K+ ratio but Ca and Fe were decreased in root and shoot of wheat seedlings. Although A. brasilense Sp7 could improve salinity tolerance in wheat via reduction of Na uptake and upregulation of TaSOS1 expression, but do not have any effect in sodium distribution within plant parts. Therefore, salinity could increase TaSOS1 expression in the root, sheath and blade and A. brasilense Sp7 also could reduce the adverse effect of salinity via addition of over expression of TaSOS1.

slovène. Slanostni stres zmanjšuje rast rastlin preko odpovedi fizioloških procesov v glavnem zaradi Na+ iona. Preobčutljiva (SOS) solna signalna pot predstavlja najvažnejši del Na+/K+ homeostaznega sistema v rastlinah v razmerah slanosti. Še več, poroča se, da je povezava pšenice z bakterijo iz rodu Azospirillum rezultirala v povečani odpornosti na slanost. Za ovrednotenje vloge bakterije iz rodu Azospirillum pri uravnavanju SOS signalne poti so bile gojene z bakterijo Azospirillum brasilense Sp7 inokulirane in neinokulirane sejanke pšenice za pet dni. Izenačene sejanke so bile prenešene v hidroponski medij z ali brez 200 mM NaCl. V presledkih 6, 24 in 48 ur po prenosu sejank v slan medij je bila merjena relativna ekspresija gena TaSOS1 v koreninah, listni nožnici in listni ploskvi in Na+/K+ razmerje. Hkrati je bila 72 ur po prenosu v slan medij izmerjena vsebnost Ca, Fe in prolina, suha masa pogankov in vsebnost topnih sladkorjev v istih delih sejank. Rezultati so pokazali, da je slanost povečala ekspresijo gena TaSOS1, vsebnost Na+, prolina in povečala količnik Na+/K+, a zmanjšala vsebnost Ca in Fe v koreninah in poganjkih sejank. Čeprav lahko bakterija A. brasilense Sp7 izboljša toleranco pšenice na slanost z zmanjšanjem privzema Na in povečano ekspresijo gena TaSOS1 pa nima nobenega učinka na razporeditev natrija v rastlini. Slanost torej lahko poveča ekspresijo gena TaSOS1 v koreninah in listih in inokulacija z bakterijo A. brasilense Sp7 lahko zmanjša škodljive učinke slanosti preko dodatnega vpliva na povečano ekspresijo TaSOS1.