Effects of drought stress on photosynthetic characteristics and ultrastructure of mesophyll cells of Mengyuan Cerasus humilis
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DOI:10.7606/j.issn.1000-7601.2019.06.06
Key Words: Mengyuan Cerasus humilis  drought stress  photosynthesis  chlorophyll content  ultrastructure
Author NameAffiliation
XING Zhongyu College of Horticulture and Plant Protection, Inner Mongolia Agricultural University, Hohhot, Inner Mongolia 010019, China 
LI Lianguo College of Horticulture and Plant Protection, Inner Mongolia Agricultural University, Hohhot, Inner Mongolia 010019, China 
GUO Jinli College of Horticulture and Plant Protection, Inner Mongolia Agricultural University, Hohhot, Inner Mongolia 010019, China 
ZHANG Xiaoyan College of Horticulture and Plant Protection, Inner Mongolia Agricultural University, Hohhot, Inner Mongolia 010019, China 
LI Xiaoyan College of Horticulture and Plant Protection, Inner Mongolia Agricultural University, Hohhot, Inner Mongolia 010019, China 
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Abstract:
      The effects of drought stress on photosynthetic parameters and ultrastructure of mesophyll cells in Mengyuan Cerasus humilis were studied with a pot experiment. The results showed that compared with normal water supply (CK), the net photosynthetic rate (Pn), transpiration rate (Tr), stomatal conductance (Gs), and water use efficiency (WUE) of Mengyuan Cerasus humilis were significantly decreased by water stress while intercellular CO2 concentration (Ci) was not significantly different from that of CK, the chlorophyll content reached the maximum and there was no obvious change and no injury symptom in ultrastructure of mesophyll cells, but the cell wall was obviously thickened under mild drought (LD) stress. The Pn, Tr, Gs, and WUE of Mengyuan Cerasus humilis continuously decreased, and Ci gradually increased, chlorophyll content was lower, and there was obvious changes and minor damages in the ultrastructure of mesophyll cells under moderate drought (MD) stress. The Pn, Tr, Gs, and WUE of Mengyuan Cerasus humilis decreased to the lowest (9.09%, 45.19%, 3.16%, and 20.39% of CK, respectively), the Ci reached the maximum (2 times of CK),chlorophyll content decreased to the lowest, and the ultrastructure of mesophyll cells was obviously changed and seriously damaged under severe drought (SD) stress, including the chloroplast membrane system collapsed, the material in the nucleus exuded, the outer mitochondrial membrane disappeared and the cell wall became thinner. It was speculated that the ultrastructure of mesophyll cells of Mengyuan Cerasus humilis was changed firstly under drought stress, then the chlorophyll synthesis and photosynthetic characteristics were affected. It was proved that Mengyuan Cerasus humilis had strong drought resistance because of its high resistance reaction to the changes of the ultrastructure.