Effects Of Bisphenol A On Physiology And Biochemistry Of Maize And Rice Seedlings

Due to the wide use of the materials containing bisphenol A（BPA） results in BPA releasing into the environment and producing the safety issues of agricultural environment. It is important to study the effects of BPA on the growth and physiological and biochemical characteristics of maize and rice seedlings. In this study, we supplemented different concentrations of BPA to the root-soaking solution of the hybrid maize variety ‘Zhengdan 958’ and rice variety ‘Kongyu 131’, to study the growth and physiological mechanism of maize and rice seedlings responsed to BPA. The main results are as follows:1. With the increase of BPA concentration, maize seedlings gradually dwarfed, leaves turned yellow, and the aboveground growth parameters were significantly suppressed above 5 mg·L^-1 BPA; photosynthetic pigment content started to decrease when BPA concentration was above 5 mg·L^-1, and decreased significantly under 50 mg·L^-1 BPA, Pn and Fv/Fm decreased significantly above（including） 5 mg·L^-1 BPA treatment, and photosynthesis was inhibited; the content of H₂O₂ and MDA increased significantly under 50 mg·L^-1 BPA, and the activities of SOD, POD and CAT were promoted mainly to eliminate excessive ROS; the content of proline and soluble protein decreased significantly above 5 mg·L^-1 BPA, and osmotic adjustment ability decreased; the activities of carbon and nitrogen metabolism key enzymes SS, SPS, NR etc. were significantly inhibited above 5 mg·L^-1 BPA, and the carbon and nitrogen metabolism were disordered.2. Dark brown spots appeared on maize roots, root apical wilted, the root growth parameters were significantly suppressed above 10 mg·L^-1 BPA; ROS content increased generally above 5 mg·L^-1 BPA, and the activities of APX and GPX of ASA-GSH circle key enzymes were activated mainly to eliminate excessive ROS; the content of proline and soluble protein of root decreased significantly above 10 mg·L^-1 BPA, and osmotic adjustment ability decreased relatively; NR, GOGAT and GDH activities were inhibited significantly above 5 mg·L^-1 BPA, and also inhibition of root nitrogen metabolism was observed.3. With the increase of BPA concentration, the phenotype of rice seedlings was similar to maize seedlings, yellow leaves, plant dwarfing, tip burning, and aboveground growth parameters were inhibited significantly above 5 mg·L^-1 BPA; photosynthetic pigment content, Pn and Fv/Fm decreased significantly above 5 mg·L^-1 BPA, and photosynthesis was inhibited; ROS content increased significantly above 5 mg·L^-1 BPA, antioxidant enzymes activity showed a downward trend under high concentration of BPA treatment, and antioxidant capacity decreased relatively; the activities of SS and SPS were significantly suppressed above 5 mg·L^-1 BPA, and NR, GS, GOGAT and GDH activities were inhibited significantly above 10 mg·L^-1 BPA, which resulted in carbon and nitrogen metabolism disturbance.4. Rice root slightly yellowed with the same colour spots, and root growth parameters were significantly suppressed above 5 mg·L^-1 BPA; H₂O₂ and MDA content increased obviously above 5 mg·L^-1 BPA, and SOD, POD, CAT activities were activated mainly to promote ROS scavenging; above 10 mg·L^-1 BPA, proline and soluble protein content increased significantly, which was conducive to root osmotic adjustment; the activity of GS, GOGAT and GDH were suppressed significantly above 10 mg·L^-1 BPA, which affected nitrogen metabolism and root growth concertedly.5. During the recovery period, the growth of maize and rice seedlings were all recovered, and recovery effect was more and more obscure with the increased concentration of BPA; the leaves of maize and rice seedlings were still yellow, and the plants were small; the recovery degree of each physiological parameters of the two crops were different, and the responsive mechanisms of different concentration of BPA were also different.