OsLEA3-2 in Salt and Drought Tolerance Response Figure 3. Subcellular localization of OsLEA3-2. (A) Diagram of the T-DNA region of the binary vector pHB::GFP::OsLEA3-2 used for transformation; (B) Subcellular localization of OsLEA3-2. The green fluorescent signal of GFP:OsLEA3-2 was detected exclusively within the nucleus of onion epidermal cells, while GFP by itself was detected both in the cytoplasm and nucleus. DIC (Differential Interference Contrast), referring to bright field images of the cells. doi:10.1371/journal.pone.0045117.g003 (Fig. 5C, D, E). The measurement of fresh/dry weight of seedlings revealed that the sorbitol stress had no clear effect on the transgenic lines, whereas it impaired the wild type growth (Fig. 5E). Homozygous OsLEA3-2 transgenic rice or wild type Zhonghua 11 seeds were soaked in water, 100 mM NaCl, 200 mM NaCl, 10% PEG 6000, 20% PEG 6000, or 10 mM ABA at 28uC. There was no difference in the growth performance between the OsLEA3-2 overexpressing transgenic rice and the wild type Zhonghua 11 treated with water (Fig. 6C). The transgenic seedlings that overexpressed OsLEA3-2 showed a stronger growth performance than the control under salinity or osmotic stress after 5 d (Fig. 6D). Even after 14 days, transgenic lines still showed higher root and shoot growth than those of the control plants (Fig. 6E). In 10% PEG, transgenic lines (L10 and L20) that overexpressed OsLEA3-2 showed a significantly stronger root growth performance than the control (P,0.05) (Fig. 6). Transgenic line L30 also had an improved growth performance. However, in 20% PEG, no striking difference was detected between transgenic line L10 and control ZH11, while L20 and L30 showed a significantly stronger growth performance than control (P,0.01). One of the three transgenic lines showed a significantly stronger growth performance than control under salinity stress, L20 in 100 mM NaCl (P,0.05) and L10 in 200 mM NaCl (P,0.05). Other lines showed a better growth performance (Fig. 6). No elevated growth performance of transgenic rice was observed under the ABA treatment and the transgenic line L20 showed the best growth performance under abiotic stress conditions. OsLEA3-2 is Able to Enhance Drought Tolerance in the Transgenic Rice Plants To examine whether the overexpression of the OsLEA3-2 gene conferred resistance to drought stress, one month old transgenic rice seedlings from lines 10 and 30 were treated in drought stress conditions for 20 days (Fig. 7A). It was found that leaves of both the wild type and transgenic plants could not expand in size after 20 days of drought stress (Fig. 7B), indicating that the drought PLOS ONE | www.plosone.org 5 September 2012 | Volume 7 | Issue 9 | e45117