To produce high-quality sweet potato plantlets rapidly at low production costs, single nodal leafy cuttings of sweet potato （Ipomoea batatas （L.） Lam.） plantlets were cultured in vitro for 14 days on sugarand phyt...To produce high-quality sweet potato plantlets rapidly at low production costs, single nodal leafy cuttings of sweet potato （Ipomoea batatas （L.） Lam.） plantlets were cultured in vitro for 14 days on sugarand phytohormone-free Murashige and Skoog （MS） liquid medium, at a photosynthetic photon flux （PPF） of 200 μmol.m^-2.s^-1 and a CO2 concentration （v/v） of 1.8×10^-3. A factorial experiment was conducted with two levels of the number of air exchanges of the vessel （NAE）, 8.7-12.2 h^-1 and 〉12.2 h^-1, and two types of supporting material, vermiculite and Florialite （a porous material）. The control treatment consisted of a pho- tomixotrophic culture using a sugar- and NAA-containing agar MS medium with an NAE of 2.4 h^-1. PPF and CO2 concentrations were the same as the photoautotrophic treatments. In comparison with the control treatment, the photoautotrophic treatments with NAE of 8.7-12.2 h^-1 （MF treatment） and ≥12.2 h^-1 （HF treatment） were, respectively, 2.2 and 2.8 times in dry weight, and 3.7 and 4.2 times in net photosynthetic rate, when Florialite was used. The survival percentages of the plantlets in the field were, respectively, 86% and 97% in the MF and HF treatments, and 35% and 46% higher than that in the control treatment. The plantlets cultured with Florialite showed greater growth, compared with those cultured with vermiculite. Photoautotrophic micropropagation system with high NAE and the use of porous supporting material can produce high-quality plantlets and make it possible to reduce production costs.展开更多
Responses of the photosynthetic activity of Phaeodactylum tricornutum （Bacillariophyta） to organic carbon glycerol were investigated. The growth rate, photosynthetic pigments, 77 K fluorescence spectra, and chloropl...Responses of the photosynthetic activity of Phaeodactylum tricornutum （Bacillariophyta） to organic carbon glycerol were investigated. The growth rate, photosynthetic pigments, 77 K fluorescence spectra, and chloroplast ultrastructure of P. tricornutum were examined under photoautotrophic, mixotrophic, and photoheterotrophic conditions. The results showed that the specific growth rate was the fastest under mixotrophic conditions. The cell photosynthetic pigment content and values of Chl a/Chl c were reduced under mixotrophic and photoheterotrophic conditions. The value of carotenoid/Chl a was enhanced under mixotrophic conditions, but was decreased under photoheterotrophic conditions. In comparison with photoautotrophic conditions, the fluorescence emission peaks and fluorescence excitation peaks were not shifted. The relative fluorescence of photosystem （PS） Ⅰ and PS Ⅱ and the values of F685/F710 and F685/F738 were decreased. Chloroplast thylakoid pairs were less packed under mixotrophic and photoheterotrophic conditions. There was a strong correlation between degree of chloroplast thylakoid packing and the excitation energy kept in PS Ⅱ. These results suggested that the PS Ⅱ activity was reduced by glycerol under mixotrophic conditions, thereby leading to repression of the photosynthetic activity.展开更多
文摘To produce high-quality sweet potato plantlets rapidly at low production costs, single nodal leafy cuttings of sweet potato （Ipomoea batatas （L.） Lam.） plantlets were cultured in vitro for 14 days on sugarand phytohormone-free Murashige and Skoog （MS） liquid medium, at a photosynthetic photon flux （PPF） of 200 μmol.m^-2.s^-1 and a CO2 concentration （v/v） of 1.8×10^-3. A factorial experiment was conducted with two levels of the number of air exchanges of the vessel （NAE）, 8.7-12.2 h^-1 and 〉12.2 h^-1, and two types of supporting material, vermiculite and Florialite （a porous material）. The control treatment consisted of a pho- tomixotrophic culture using a sugar- and NAA-containing agar MS medium with an NAE of 2.4 h^-1. PPF and CO2 concentrations were the same as the photoautotrophic treatments. In comparison with the control treatment, the photoautotrophic treatments with NAE of 8.7-12.2 h^-1 （MF treatment） and ≥12.2 h^-1 （HF treatment） were, respectively, 2.2 and 2.8 times in dry weight, and 3.7 and 4.2 times in net photosynthetic rate, when Florialite was used. The survival percentages of the plantlets in the field were, respectively, 86% and 97% in the MF and HF treatments, and 35% and 46% higher than that in the control treatment. The plantlets cultured with Florialite showed greater growth, compared with those cultured with vermiculite. Photoautotrophic micropropagation system with high NAE and the use of porous supporting material can produce high-quality plantlets and make it possible to reduce production costs.
基金Supported by the National Natural Science Foundation of China (30770336,30370231 and 40876074).
文摘Responses of the photosynthetic activity of Phaeodactylum tricornutum （Bacillariophyta） to organic carbon glycerol were investigated. The growth rate, photosynthetic pigments, 77 K fluorescence spectra, and chloroplast ultrastructure of P. tricornutum were examined under photoautotrophic, mixotrophic, and photoheterotrophic conditions. The results showed that the specific growth rate was the fastest under mixotrophic conditions. The cell photosynthetic pigment content and values of Chl a/Chl c were reduced under mixotrophic and photoheterotrophic conditions. The value of carotenoid/Chl a was enhanced under mixotrophic conditions, but was decreased under photoheterotrophic conditions. In comparison with photoautotrophic conditions, the fluorescence emission peaks and fluorescence excitation peaks were not shifted. The relative fluorescence of photosystem （PS） Ⅰ and PS Ⅱ and the values of F685/F710 and F685/F738 were decreased. Chloroplast thylakoid pairs were less packed under mixotrophic and photoheterotrophic conditions. There was a strong correlation between degree of chloroplast thylakoid packing and the excitation energy kept in PS Ⅱ. These results suggested that the PS Ⅱ activity was reduced by glycerol under mixotrophic conditions, thereby leading to repression of the photosynthetic activity.
