3.3 | The phosphotransferase activity in the medium
D and T stresses can up-regulate the activity of S-PT in the culture medium, whereas all stresses except N stress can reduce the activity of S-PT in the culture medium (p <0.05) (Figure 3). Drought or high-temperature or the synergistic stresses of drought and high-temperature can significantly reduce the effect of nitrogen deficiency on up-regulating S-PT activity (e.g., DN, TN, and DTN stresses) (p <0.05) (Figure 3-a). Moreover, drought can alleviate the effect of phosphorus deficiency on down-regulating S-PT activity, while the synergistic stresses of drought and high-temperature can aggravate the effect of phosphorus deficiency on down-regulating S-PT activity (e.g., DP and DTP stresses) (p <0.05) (Figure 3-b). Furthermore, drought or high-temperature or synergistic stresses of drought and high-temperature can alleviate the effect of nitrogen and phosphorus deficiency on the inhibition of S-PT activity (e.g., DNP, TNP, and DTNP stresses) (p <0.05) (Figure 3-c). Finally, synergistic stresses of drought and high-temperature inhibit the induction effect of a single factor on S-PT activity (e.g., DT stress) (p <0.05) (Figure 3-d). It shows that under D and T, plants secrete S-PT through the root system to improve the transport and utilization of phosphorus, but most stresses are not conducive to the transport and utilization of phosphorus.