Objectives Abscisic acid (ABA) is capable of regulating plant growth, seed dormancy and leaf senescence, decreasing response to different abiotic stresses. We studied the response difference of B. napus to Cd stress under different ABA supplying levels, to increase the knowledge of ABA in regulating the physiological process and N nutrient.
Methods The B. napus (No. 814) was treated under three circumstances: normal culture (CK), 10 μmol/L CdCl2 (Cd), 5 μmol/L ABA + 10 μmol/L CdCl2 (A + Cd). After 4 days of treatment, the phenotypes, proline and MDA content, Cd concentration, NO3– and NH4+ concentration, as well as NR and GS activities of B. napus were measured.
Results Compared with Cd treatment, the SPAD value of B. napus new leaves in A + Cd was increased by 1.1 times, the proline concentration in the roots increased by 29.0%, and the malondialdehyde concentration decreased by 48.3%. The addition of exogenous ABA inhibited the absorption of cadmium in B. napus, decreased the Cd concentration in the shoots and roots, reduced the toxic effect of cadmium on B. napus, and also affected the absorption of NO3– in B. napus and reduced the total N concentration in B. napus. Compared with Cd treatment, the addition of ABA significantly increased the NR activity in the roots of B. napus by 82.8%, enhanced the distribution of NH4+ to the shoots, and the activity of GS in the shoots increased by 32.1%, which stimulated the N assimilation and metabolism in B. napus, and the physiological nitrogen use efficiency increased significantly by 17.2%.
Conclusions The addition of exogenous ABA can reduce the absorption of Cd, increase the enzyme activities related to nitrogen metabolism, promote the synthesis of proline and decrease the production of malondialdehyde, thereby enhance the resistance of B. napus to Cd, and enhance the nitrogen assimilation and metabolism in B. napus, and increase the nitrogen use efficiency as well.
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