Role of antioxidant pool in management of ozone stress through soil nitrogen amendments in two cultivars of a tropical legume

Abstract

The present experiment was done on two different cultivars of a tropical legume, Cymopsis tetragonoloba L. Taub. (cluster bean) cvv. Pusa-Naubahar (PUSA-N) and Selection-151 (S-151). The experiment was conducted under ambient ozone (O3) conditions with inputs of three different doses of inorganic nitrogen (N1, recommended; N2, 1.5-times recommended and N3, 2-times recommended) as well as control plants. The objective of this study was to evaluate the effectiveness of soil nitrogen amendments in management of ambient ozone stress in the two cultivars of C. tetragonoloba. Our experiment showed that nitrogen amendments can be an efficient measure to manage O3 injury in plants. Stimulation of antioxidant enzyme activities under nitrogen amendments is an important feature of plants that help plants cope with ambient O3 stress. Nitrogen amendments strengthened the antioxidant machinery in a more effective way in the tolerant cultivar PUSA-N, while in the sensitive cultivar S-151, avoidance strategy marked by more reduction in stomatal conductance was more prominent. Enzymes of the Halliwell–Asada pathway, especially ascorbate peroxidase and glutathione reductase, were more responsive and synchronised in PUSA-N than S-151, under similar nitrogen amendment regimes and were responsible for the differential sensitivities of the two cultivars of C. tetragonoloba. The present study shows that 1.5-times recommended dose of soil nitrogen amendments was sufficient in partial mitigation of O3 injury and the higher nitrogen dose (2-times recommended, in our case), did not provide any extra advantage to the plant’s metabolism compared with plants treated with the lower nitrogen dose (1.5-times recommended).

Combating ozone stress through N fertilization: A case study of Indian bean (Dolichos lablab L.)

“…Out of the two varieties of Dolichos lablab L. exposed to ambient and elevated O 3 concentrations, Kashi Sheetal had higher endogenously generated H 2 O 2 in its control leaves as compared to Kashi Harittima, as evident through the histochemical assay of H 2 O 2 localization (Figure 4). Related findings have reported that cultivars with higher levels of endogenous H 2 O 2 are more tolerant than cultivars with lower levels of H 2 O 2 (Caregnato et al, 2013;Yadav et al, 2019;Gupta and Tiwari, 2020). Caregnato et al (2013) reported significantly higher H 2 O 2 localization in the leaves of two varieties of Phaseolus vulgaris L. grown in EO 3 conditions in comparison to AO 3 conditions.…”

“…It was reported that H 2 O 2 was produced in the leaves of Cymopsis tetragonoloba L. Taub. (Cluster bean) was significantly decreased with increasing nitrogen amendment doses (Gupta and Tiwari, 2020). It is suggested that the surplus nitrogen available to the plant gets allocated to improve the antioxidative potential of the plants which results in improved scavenging of the H 2 O 2 (Podda et al, 2019).…”

“…This is further proved by significant correlation coefficient values of different physiological parameters of O 3 -exposed plants upon N amendments (Tables 2, 3). Increased g s upon N amendments have been reported in wheat (Wall et al, 2000), larch (Mao et al, 2014), cluster bean (Gupta and Tiwari, 2020), etc. A decrease in g s along with an increased A upon N amendments and O 3 exposure in poplar has been reported by Zhang et al (2018).…”

Role of Elevated Ozone on Development and Metabolite Contents of Lemongrass [Cymbopogon flexuosus (Steud.) (Wats.)]

“…In the present study, the discrepancy of enzymatic response at different developmental stages in EO 1 and EO 2 plants can be well-correlated to the respective ROS contents. Whereas SOD catalyses the dismutation of O 2 −0 and H 2 O 2 , APX and CAT are responsible for scavenging H 2 O 2 [ 18 , 71 , 72 ]. Non-significant variations in O 2 −0 accompanied by an increase in H 2 O 2 contents demonstrate the rapid activity of SOD.…”

“…NOx levels in India showed an annual increasing trend of 0.9 ppb from 2010 to 2015 [ 8 ]. In India, the middle Indo-Gangetic Plains have seen high concentrations in the last few years, as made evident by a number of studies [ 17 , 18 ].…”