JIA-2019-11

2509 LI Li-shu et al. Journal of Integrative Agriculture 2019, 18(11): 2505–2513 And the expression in fruit was the highest (Fig. 2-A). The expression of MieIF1A-b exhibited continuously increasing during the growth of fruit and reached the highest level in F8 fruit (Fig. 2-B). NaCl and PEG treatments increased the accumulation of the MieIF1A-b transcript during the first 12 h and caused a small decrease from 12 to 24 h. At 36 h under salt treatment and 48 h under 30% PEG, the accumulation of the MieIF1A-b transcript was up-regulated by 2.4- and 2.2-fold, respectively. Finally, MieIF1A-b gene expression levels declined again after reaching the highest transcript level. Low-temperature treatment first down-regulated MieIF1A-b gene expression during the first 24 h. Then, this treatment up-regulated MieIF1A-b gene expression, which reached the highest transcript level (1.7-fold) at 48 h (Fig. 2-C). The expression of MieIF1A-b was significantly up-regulated under the H 2 O 2 and ABA treatments. And MieIF1A-b reached the highest transcript levels, 9.8- and 4.9-fold, at 4 and 8 h, respectively. SA treatment first down- regulated MieIF1A-b gene expression during the first 2 h and then up-regulated the expression, which reached the highest transcript level, 2.8-fold, at 8 h (Fig. 2-D). These results indicated that the MieIF1A-b gene is highly expressed in fruit and significantly responds to salt, drought, ABA and H 2 O 2 stress treatment. 3.3. Detection of GUS staining in different tissues of A. thaliana To test whether the MieIF1A-b gene was normally expressed in transgenic plants (Appendix B), we used three transgenic lines (L4, L10 and L21), and WT A . thaliana to perform GUS staining in different tissues. The GUS gene was expressed in the roots, stems, leaves, inflorescences, calyces, stigmas, fruit pods, and whole seedlings of the three transgenic lines (L4, L10 and L21); conversely, the tissues of the WT A . thaliana were not stained blue and appeared white (Fig. 3). The results indicated that the MieIF1A-b gene was highly expressed in the various organs of transgenic A . thaliana plants. 3.4. Phenotypic observation of transgenic A. thaliana plants To further understand the function of MieIF1A-b in transgenic A . thaliana plants, we observed the phenotype in the present study. The results showed that plant height, main root length Relative expression level Relative expression level Relative expression level Relative expression level Stress time (h) Stress time (h) A B D C 40 20 0 30 50 10 70 60 40 20 0 30 50 10 70 60 6 0 4 8 2 10 1.5 0 1.0 2.0 0.5 2.5 YL YS F4 FL 0 12 96 24 NaCl PEG 4°C H 2 O 2 ABA SA OL OS F1 F8 F1 F3 F7 F5 F2 F4 F6 F8 36 72 48 0 1 24 2 12 8 4 * * * * * * * * * * * * * * Fig. 2 Expression profiles of eukaryotic translation initiation factor ( eIF1A ) in Mangifera indica ( MieIF1A-b ). A, different tissues. YL, young leaves; OL, old leaves; YS, young stems; OS, old stems; FL, flowers; F1, F4 and F8, fruits 10, 40 and 80 d after flowering. B, different fruit development stages (F1–F8, 10, 20, 30, 40, 50, 60, 70, and 80 d after flowering, respectively). C, under abiotic stress treatment. D, under hormone treatments. Error bars indicate SE. * denotes significant differences ( P <0.05).