›› 2020, Vol. 32 ›› Issue (8): 1466-1474.DOI: 10.3969/j.issn.1004-1524.2020.08.17

• Biosystems Engineering • Previous Articles     Next Articles

Construction of plant root tip mesenchymal sensors and their effects on urea sensing dynamics

NIU Bo1, LI Lina1, PANG Guangchang1,*, LU Dingqiang2,*   

  1. 1. College of Biotechnology and Food Science, Tianjin University of Commerce, Tianjin 300134, China;
    2. Tianjin Key Laboratory of Food Biotechnology, Tianjin 300134, China
  • Received:2020-02-05 Online:2020-08-25 Published:2020-08-28

Abstract: The plant root tip tissue sensor was constructed to quantitatively measure the root tip tissue's ability to sense urea and to explore the dynamics of the interaction between the two. In this study, sodium alginate-starch gel was used as a fixative. The meristems of corn, pepper, cauliflower and cucumber were fixed between two nuclear microporous membranes to make a “sandwich” urea sensing membrane. It was fixed and sealed on a glassy carbon electrode to make a plant root tip meristem sensor. Electrochemical workstations and time-current curve methods were used to determine the changes in electrochemical signals produced by the interaction of urea with root meristem sensors of corn, pepper, cauliflower, and cucumber. Compared with the blank control group, the root-tip meristem sensors of four plants showed a clear functional relationship to different concentrations of urea. Corn, pepper, cauliflowerand cucumber exhibited enzymatic response characteristics (linked allosteric effect) was similar to enzyme and substrate responses in the range of 10-8-10-4,10-16-10-6,10-19-10-10 and 10-20-10-10mol·L-1 urea. Further analysis showed that the linked allosteric constants Ka (similar to the Mie constants Km of enzyme-bottom catalytic kinetics) of corn, pepper, cauliflower, cucumberand urea were: 7.197 0×10-9, 4.537 0×10-16, 9.908 5×10-20 and 6.462 8×10-21mol·L-1. It was indicated that corn's ability to sense urea was at least 7 orders of magnitude worse than that of the other three plants. Corn and pepper were cultivated under the condition that urea was the only exogenous nitrogen nutrient. The experimental results showed that at a concentration lower than the corn's ability to sense urea (1×10-10mol·L-1), the corn died within 10-15 days and peppers could grow normally. It was proved that the linkage allosteric constant Ka obtained in this study reflected the true sensing ability of plant root-tip meristems to ureaand that corn's sensing of urea has some defects.

Key words: corn, pepper, cauliflower, cucumber, root-tip meristem, electrochemical sensor, urea, sensing kinetics

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