| Changes of antioxidant enzymes in cadmium (Cd)-stressed transgenic rice (Oryza sativa L. cv. Zhonghua No.11) carrying glutathione-S-transferase (GST) and catalasel (CAT1) and non-transgenics roots and shoots were analyzed. Data showed that the activities of all antioxidant enzymes such as, CAT, GST, SOD, APX, DHAR and GR measured in the stressed transgenics roots and shoots were significantly different from those of non-transgenics. The mitigated oxidative damage induced by Cd in the transgenics resulted from the coordination of multi-antioxidant enzymes.The effect of IBA, H2O2 and O2-on root development in Cd-stressed rice (Oryza sativa L. cv. Zhonghua No.11) was analyzed. Results showed that the length of primary, adventitious and lateral roots as well as lateral root number is increased by single Cd, Cd supplemented with IBA or AT or DDC treatments, but reduced by Cd plus TIBA or DMTU or Tiron applications. A genome-wide expression analysis of OsPINs, OsPID, OsARFs, and cell cycle genes in difference-treated roots was conducted by using semi-quantitative reverse transcription-PCR. A total of 44,48,66 and 59 out of all 98 tested genes were regulated by Cd, H2O2, O2- and auxin, respectively. In these 98 genes, cadmium regulated 33 genes were also induced by H2O2; while 38 genes regulated by Cd were also induced by auxin; whereas 44 genes were regulated either by Cd or by O2-; there were 53 genes induced by both auxin and O2-; there were 36 genes regulated not only by Cd but also by auxin or O2-; and 29 genes were simultaneously regulated by Cd, auxin, H2O2 and O2-. Our data indicated that the regulation of root system in Cd-stressed rice is a complex process involving plant hormone, reactive oxygen species (ROS) and cell cycle. The altered gene expression profiles caused by Cd, H2O2,02- and auxin implied that a tight connection/crosstalk between Cd, axuin, ROS and cell cycle may be existence during regulation of Cd-stressed root growth.
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