The objectives of this study were to determine the effects of yellow light (Y), green light (G), and two blue lights (B) at different wavelengths in conjunction with red light (R) on the growth and morphogenesis of potato plantlets in vitro. Randomized nodal explants were cut into 1.0–1.5 cm pieces and were grown under five different light conditions: fluorescent white light (FL); the combined spectra of R, Y, and B at 445 nm (R630B445Y); the combined spectra of R, G, and B at 445 nm (R630B445G); the combined spectra of R, Y, and B at 465 nm (R630B465Y); and the combined spectra of R, G, and B at 465 nm (R630B465G). Morphogenesis and physiological parameters were investigated. The results showed that R630B445Y and R630B465Y increased the fresh weight (FW), dry weight (DW), stem diameter, blade number, leaf area, specific leaf weight (SLW), and the health index of potato plantlets in vitro; root activity increased significantly; and soluble sugar, soluble protein, and starch also increased. The addition of Y to the combined spectra of R and B contributed to the growth, development, and morphogenesis more than the combined spectra of R and B with G, and B at 445 nm was more effective at promoting plant growth than was B at 465 nm.
Ruining Li, Wenwen Huang, Xiaoxiao Wang, Xiaoying Liu and Zhigang Xu
Liu XiaoYing, Guo ShiRong, Xu ZhiGang, Jiao XueLei and Takafumi Tezuka
The chloroplast structural alteration and the photosynthetic apparatus activity of cherry tomato seedlings were investigated under dysprosium lamp [white light control (C)] and six light-emitting diode (LED) light treatments designated as red (R), blue (B), orange (O), green (G), red and blue (RB), and red, blue, and green (RBG) with the same photosynthetic photon flux density (PPFD) (≈320 μmol·m−2·s−1) for 30 days. Compared with C treatment, net photosynthesis of cherry tomato leaves was increased significantly under the light treatments of B, RB, and RBG and reduced under R, O, and G. Chloroplasts of the leaves under the RB treatment were rich in grana and starch granules. Moreover, chloroplasts in leaves under RB seemed to be a distinct boundary between granathylakoid and stromathylakoid. Granathylakoid under treatment B developed normally, but the chloroplasts had few starch granules. Chloroplasts under RBG were similar to those under C. Chloroplasts under R and G were relatively rich in starch granules. However, the distinction between granathylakoid and stromathylakoid under R and G was obscure. Chloroplasts under O were dysplastic. Palisade tissue cells in leaves under RB were especially well-developed and spongy tissue cells under the same treatment were localized in an orderly fashion. However, palisade and spongy tissue cells in leaves under R, O, and G were dysplastic. Stomatal numbers per mm2 were significantly increased under B, RB, and RBG. The current results suggested blue light seemed to be an essential factor for the growth of cherry tomato plants.
Ruining Li, Jiahuan Long, Yongzhe Yan, Jiaming Luo, Zhigang Xu and Xiaoying Liu
Monochromatic light and wide-band white light both affect plant growth and development. However, the different effects between monochromatic light and addition white light to monochromatic light on the formation, growth, and dormancy of microtubers have not been fully explored. Therefore, we evaluated these effects using in vitro potatoes grown under pure blue and red lights and a combination of blue light and red light supplemented with white light, respectively. Current results suggested that light spectra influenced microtuber formation, growth, and dormancy by regulating potato plantlet morphogenesis, affecting the synthesis and transportation of photosynthetic metabolites, and altering the accumulation and distribution of biomass in various plant tissues. Monochromatic lights and the combined spectra had differing effects. For instance, monochromatic red light induced the growth of more microtubers, whereas addition white light to red light decreased number but increased weight of microtubers. Meanwhile, monochromatic blue light facilitated tuber growth, whereas addition white light to blue light decreased microtubers weight but increased microtuber number. In addition, composite lights of addition white light to monochromatic red and blue lights both extended the dormancy period, and monochromatic blue light shortened the dormancy period of microtubers >300 mg. Therefore, in microtuber agricultural production, specific light conditions may be applied at different growth stages of in vitro potatoes to increase the number of effective microtubers (>50 mg) and to satisfy storing requirement of seed microtubers.
Wei Hu, Ju-Hua Liu, Xiao-Ying Yang, Jian-Bin Zhang, Cai-Hong Jia, Mei-Ying Li, Bi-Yu Xu and Zhi-Qiang Jin
The banana, a typical climacteric fruit, undergoes a postharvest ripening process followed by a burst in ethylene production that signals the beginning of the climacteric period. Postharvest ripening plays an important role in improving the quality of the fruit as well as limiting its shelf life. To investigate the role of glutamate decarboxylase (GAD) in climacteric ethylene biosynthesis and fruit ripening in postharvest banana, a GAD gene was isolated from banana, designated MuGAD. Coincidently with climacteric ethylene production, MuGAD expression as well as the expression of the genes encoding the Musa 1-aminocyclopropane-1-carboxylate synthase (MaACS1) and Musa 1-aminocyclopropane-1-carboxylate oxidase (MaACO1) greatly increased during natural ripening and in ethylene-treated banana. Moreover, ethylene biosynthesis, ripening progress, and MuGAD, MaACS1, and MaACO1 expression were enhanced by exogenous ethylene application and inhibited by 1-methylcyclopropene (1-MCP). Taken together, our results suggested that MuGAD is involved in the fruit ripening process in postharvest banana.