Physiological characterizations and expression levels of ERF genes under different osmotic stresses during submergence in rice seedlings (Oryza sativa L.)

• Main Authors: Hsin-Yu Chi, 紀欣妤
• Other Authors: Chin-Ying Yang
• Format: Others
• Language: en_US
• Published: 2018
• Online Access: http://ndltd.ncl.edu.tw/handle/mxxg7w

碩士 === 國立中興大學 === 國際農學碩士學位學程 === 106 === As a natural disaster, flooding effects on rice production enormously, while submergence not only causes hypoxic stress but osmotic stress. To understand the mechanisms between the submergence and osmotic stress, it is necessary to observe physiological responses and to identify the ERF-VIIs family genes expression under different osmotic stress during submergence in rice seedlings. In this study we used IR64 and IR64-Sub1 as plant materials, the plant height of IR64 were increased rapidly compared with IR64-Sub1 seedlings under submergence (Sub), submergence combined with mannitol (Sub+Man) and submergence combined with NaCl (Sub+NaCl). Among different treatments, the plant height of rice seedlings whether IR64 or IR64-Sub1 were significant shorter under Sub+Man and Sub+NaCl treatments than Sub treatment, especially under Sub+Man treatment. The chlorophyll concentration of IR64 was decreased significantly under different treatments compared with IR64-Sub1, and both seedlings had the highest chlorophyll concentration under Sub+Man treatment compared with Sub and Sub+NaCl treatments. The malondialdehyde (MDA) concentration of IR64 seedlings were higher than IR64-Sub1 under different treatments, while seedlings under Sub+NaCl treatments had the highest MDA concentration. Analysis of survival rate showed that IR64-Sub1 seedlings presented higher survival rate under Sub+Man and Sub+NaCl treatments compared with IR64 seedlings. Therefore, we inferred that IR64-Sub1 with higher tolerance under different osmotic stress during submergence. The DAB and NBT staining results showed that IR64-Sub1 accumulated the highest H2O2 and O2- under Sub+NaCl treatment. Moreover, Evans blue staining of IR64- Sub1 was shown the most severe cells’ damage under Sub+NaCl treatment than other treatments. The antioxidant activity of IR64-Sub1 was shown that catalase (CAT) and superoxidase dismutase (SOD) activities decreased under all treatments; however total peroxidase (POX) increased under all treatments. Ascorbate peroxidase (APX) activity increased under Sub+Man treatment compared with Sub and Sub+NaCl treatments. The qRT-PCR results revealed that the expression level of ADH1 and LDH1 were induced higher than under Sub+Man and Sub+NaCl treatments compared with Sub treatment. The expression level of ERF-VIIs family genes such as Sub1A, Sub1B, Sub1C and BGIOSGA012597 were induced under different treatments. The expression level of BGIOSGA022463 were induced under Sub and Sub+Man treatments compared with Sub+NaCl treatment. Taken together, IR64-Sub1 had higher tolerance under different osmotic stress during submergence. In the future, the studies of ERF-VIIs regulation may help rice seedlings facing different osmotic stress during submergence.