PMC

(A) Gross difference in the growth of the untransformed banana plant and p1301-MusamiRNA156 derived transgenic banana plant. (B) Poor development of the root system in the two plants 1 month post hardening. Difference in the leaf anatomy of the untransformed banana plant and p1301-MusamiRNA156 derived transgenic banana plant (C, D and E). Growth difference seen in the untransformed banana plant and p1301-MusamiRNA156 derived banana plant, three months post hardening (F). Microscopic examination of the leaf cellular pattern seen in the untransformed banana plant and p1301-MusamiRNA156 derived transgenic banana plant (G and H).

a I₂-KI staining of MaSBE2.3-downregulated banana fruit discs. b Expression level of the MaSBE2.3 gene in MaSBE2.3-downregulated banana fruit discs. c Change in total starch content in MaSBE2.3-downregulated banana fruit discs. d Change in amylopectin content in MaSBE2.3-downregulated banana fruit discs. e I₂-KI staining of MaSBE2.3-overexpressing banana fruit discs. f Expression level of the MaSBE2.3 gene in MaSBE2.3-overexpressing banana fruit discs. g Change in total starch content in MaSBE2.3-overexpressing banana fruit discs. h Change in amylopectin content in MaSBE2.3-overexpressing banana fruit discs. Biological replicates were tested in triplicate, and the asterisks indicate significant differences compared to pTRV1+pTRV2 (empty vector control) or pCAMBIA1304 (empty vector control) (*p < 0.05; **p < 0.01)

Electron microscope observation for effects of SA on ultrastructure in chilling-stressed banana seedling leaves. (a) Mesophyll cells of banana seedlings growing at normal growth conditions (30/22 °C); (b) Mesophyll cells of banana seedlings treated by 0.5 mmol/L SA at 30/22 °C for 1 d; (c) Mesophyll cells of banana seedlings suffered from 7 °C stress for 3 d; (d) Mesophyll cells of SA-pretreated banana seedlings suffered from 7 °C stress for 3 d; (e) Chloroplast of mesophyll cells of banana seedlings growing at 30/22 °C; (f) Chloroplast of mesophyll cells of banana seedlings treated by SA at 30/22 °C for 1 d; (g) Chloroplast of mesophyll cells of banana seedlings suffered from 7 °C stress for 3 d; (h) Chloroplast of mesophyll cells of SA-pretreated banana seedlings suffered from 7 °C stress for 3 d; (i) Thylakoid of mesophyll cells of banana seedlings growing at 30/22 °C; (j) Thylakoid of mesophyll cells of banana seedlings treated by SA at 30/22 °C for 1 d; (k) Thylakoid of mesophyll cells of banana seedlings suffered from 7 °C stress for 3 d; (l) Thylakoid of mesophyll cells of SA-pretreated banana seedlings suffered from 7 °C stress for 3 d; (m) Mitochondria of mesophyll cells of banana seedlings growing at 30/22 °C; (n) Mitochondria of mesophyll cells of banana seedlings treated by SA at 30/22 °C for 1 d; (o) Mitochondria of mesophyll cells of banana seedlings suffered from 7 °C stress for 3 d; (p) Mitochondria of mesophyll cells of SA-pretreated banana seedlings suffered from 7 °C stress for 3 d
C: Cell membrane; CH: Chloroplast; CM: Chloroplast membrane; CR: Crevice; GT: Grana thylakoid; L: Lipid droplet; M: Mitochondria; MC: Mitochondria cristae; MM: Mitochondria membrane; N: Nucleus; S: Starch; ST: Stromal thylakoid; V: Vacuole; VE: Vesicle. White lines of black panes express bars of magnification

Light microscopy observation for effects of SA on cell structure in chilling-stressed banana seedling leaves. (a) Mesophyll cells of banana seedlings growing at 30/22 °C (10×40); (b) Mesophyll cells of banana seedlings treated by 0.5 mmol/L SA at 30/22 °C for 1 d (10×40); (c) Mesophyll cells of banana seedlings suffered from 7 °C stress for 3 d (10×40); (d) Mesophyll cells of SA-pretreated banana seedlings suffered from 7 °C stress for 3 d (10×40); (e) Mesophyll cells of banana seedlings growing at 30/22 °C (10×100); (f) Mesophyll cells of banana seedlings treated by 0.5 mmol/L SA at 30/22 °C for 1 d (10×100); (g) Mesophyll cells of banana seedlings suffered from 7 °C stress for 3 d (10×100); (h) Mesophyll cells of SA-pretreated banana seedlings suffered from 7 °C stress for 3 d (10×100)
CE: Cell; F: Fibro; P: Palisade parenchymas