Priming of tomato seedlings with 2‐oxoglutarate induces arsenic toxicity alleviatory responses by involving endogenous nitric oxide

Abstract

Metal toxicity in crop plants is a matter of scientific concern. Therefore, in recent years efforts have been made to minimize metal toxicity in crop plants. Out of various strategies, priming of seedlings with certain chemicals, like e.g. donors of signaling molecules, nutrients, metabolites or plant hormones has shown encouraging results. However, mechanisms related with the priming‐induced mitigation of metal toxicity are still poorly known. Hence, we have tested the potential of 2‐oxoglutarate (2‐OG) priming in enhancing the arsenate (AsV) toxicity tolerance in tomato seedlings along with deciphering the probable role of nitric oxide (NO) in accomplishing this task. Arsenate decreased growth, endogenous NO and nitric oxide synthase‐like activity but enhanced the accumulation of As, which collectively led to root cell death. Arsenate toxicity also decreased some photosynthetic characteristics (i.e. Fv/Fm, qP, Fv/F0 and Fm/F0, and total chlorophyll content) but enhanced NPQ. However, priming with 2‐OG alleviated the toxic effect of AsV on growth, endogenous NO, cell death and photosynthesis. Moreover, arsenate inhibited the activities of enzymes of nitrogen metabolism (i.e. nitrate reductase, nitrite reductase, glutamine synthetase and glutamine 2‐oxoglutarate aminotransferase) but increased the activity of glutamate dehydrogenase and NH4+ content. Superoxide radicals, hydrogen peroxide, lipid peroxidation, protein oxidation and membrane damage increased upon AsV exposure, but the antioxidant enzymes (i.e. superoxide dismutase, catalase and glutathione‐S‐transferase) showed differential responses. Overall, our results showed that 2‐OG is capable of alleviating AsV toxicity in tomato seedlings but the involvement of endogenous NO is probably required.

Regulating Effect of Exogenous α-Ketoglutarate on Ammonium Assimilation in Poplar

“…Our findings suggest that AKG supplementation significantly enhances growth parameters in poplar Nanlin 895 under high ammonium levels, evidenced by notable increases in height and biomass (Figure 1). These observations were in alignment with prior reports that demonstrate the growth-promoting effects of exogenous AKG application in various crops [19,20,[22][23][24][25][26][27], implying that the role of AKG in ammonium detoxification is conserved in different organisms.…”

“…Plants utilize two primary pathways for ammonium assimilation: the GS/GOGAT cycle and the GDH-mediated reaction [14,38]. Our investigation showed that AKG administration led to a decrease in GDH and AspAT activities in the leaves (Figure 4c,d), akin to findings in tomato plants [23], indicating that the GDH-mediated reaction is a low ammonium affinity pathway [40] in poplars treated with AKG under high ammonium stress. By contrast, exogenous AKG enhanced the expression of PtrGS1 and PtrGS2 (Figure 9b) and stimulated GS/GOGAT enzyme activities in the leaves (Figure 4a,b), suggesting that the GS/GOGAT cycle is preferential for AKG-mediated ammonium detoxification in poplars.…”

“…Moreover, emerging evidence has shown that exogenous AKG application promotes ammonia utilization, carbon and nitrogen metabolism, and increases crop yield [19][20][21]. In addition, AKG has been reported to enhance plant stress resistance by reducing oxidative stress markers and boosting antioxidant defenses, contributing to better plant growth and adaptability in different challenging environments [22][23][24][25][26][27].…”

Detection of Nitric Oxide from Chickpea Using DAF Fluorescence and Chemiluminescence Methods

“…Fukudome, Watanabe, Osuki, Uchi, and Uchiumi (2019) reported endogenous NO increases during root‐nodule symbiosis of Lotus japonica using DAF‐FM DA. Visualization of NO was performed during arsenic toxicity in tomato roots using DAF‐2DA (Alamri et al., 2021). Thymol increased the NO in tobacco seedlings as measured by DAF‐FM DA (Xu et al., 2022).…”

The reprogramming of mitochondrial energy metabolism in Rice: The role of the TCA cycle and GABA shunt under Arsenic exposure

“…Differential respiration responses, namely, extensive metabolite content changes, are among the common responses of plants to As toxicity (Saini et al, 2023). 2-oxoglutarate dehydrogenase complex (2-OGDC) is a key metabolic enzyme necessary for the cyclic operation of the TCA cycle (Alamri et al, 2021). This enzyme is found to be one of the prime targets of metalloids and is physiochemically inhibited by them (Wei et al, 2022).…”