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Molecular Mechanisms of Polyamines-Induced Abiotic Stress Tolerance in Plants
Published in Hasanuzzaman Mirza, Nahar Kamrun, Fujita Masayuki, Oku Hirosuke, Tofazzal M. Islam, Approaches for Enhancing Abiotic Stress Tolerance in Plants, 2019
Hu et al. (2016) studied the beneficial role of spermidine in tomato seedlings under salinity-alkalinity stress. They investigated the chlorophyll metabolism and D1 protein content, and they found that expression of chlorophyll biosynthesis gene porphobilinogen deaminase PBGD and psbA, which codes for D1 were enhanced, whereas the expression of Chlase, which codes for chlorophyllase was reduced when Spd was exogenously applied. They concluded that the protective effect of Spd on chlorophyll and D1 protein content during stress might maintain the photosynthetic apparatus, permitting continued photosynthesis and growth of tomato seedlings (Solanum lycopersicum cv. Jinpengchaoguan) under salinity-alkalinity stress.
2-Hydroxymelatonin induced nutritional orchestration in Cucumis sativus under cadmium toxicity: modulation of non-enzymatic antioxidants and gene expression
Published in International Journal of Phytoremediation, 2020
Anis Ali Shah, Shakil Ahmed, Nasim Ahmad Yasin
Chlorophyll is a crucial cellular component involved in synthesis photosynthate, thus maintains metabolic homeostasis in plants. Heavy metal toxicity halts the process of photosynthate formation due to interruption in photosynthetic e−1 transport process (Paunov et al. 2018). Heavy metal toxicity enhanced chlorophyllase activity and reduced nutrient uptake in plants (Bhattacharjee and Mukherjee 2003). Cadmium decreases the activity of enzymes involved in synthesis of chlorophyll structure i.e. aminolevulinic dehydratase, porphobilinogen deaminase and protochlorophyllide reductase (Noriega et al. 2007). Moreover, Cd degrades chlorophyll structure by replacing Mg2+. During the current research, 2OHMT improved chlorophyll content by enhancing the uptake of Mg2+ from rhizosphere.
Response to cadmium and phytostabilization potential of Platycladus orientalis in contaminated soil
Published in International Journal of Phytoremediation, 2018
Peng Zeng, Zhaohui Guo, Xiyuan Xiao, Xia Cao, Chi Peng
Photosynthesis is an important process for plant growth and biomass production, and the photosynthetic pigment content in plant leaves can reflect the intensity of photosynthesis (Liu et al. 2015). After 56 d of cultivation, there was no significant influence of Cd on the chlorophyl contents in leaves of P. orientalis in the T1 treatment, but the contents of chlorophyl a, chlorophyl b and carotenoids in the T2 treatment were obviously decreased by 14.2%, 20.7% and 8.48%, respectively, compared with the CK treatment (Figure 2). With the extended cultivation time of 105 d, the contents of chlorophyl a, chlorophyl b and carotenoids from the T1 and T2 treatments were also decreased by approximately 18.2% to 32.0%, respectively. Therefore, Cd in soil had an adverse influence on the chlorophyl synthesis of P. orientalis during the early growing period. This result may be because Cd2+ can interfere with chlorophyl formation by interacting with sulfhydryl-requiring enzymes like aminolevulinic acid dehydratase, porphobilinogen deaminase and protochlorophyllide reductase, which directly or indirectly inhibited chlorophyl synthesis (Somashekaraiah et al. 1992). Furthermore, the toxicity of Cd in soil could inhibit the synthesis of photosynthetic pigments in many plant species such as Macleaya cordata (Nie et al. 2016), Eucalyptus camaldulensis (Pietrini et al. 2015) etc. However, the chlorophyl contents were slightly changed under the T1 and T2 treatments compared to the CK treatment after 154 d of cultivation. Generally, plants could adopt different strategies to reduce Cd-induced oxidative damage, such as increasing the activities of antioxidative enzymes to maintain the plants normal photosynthesis (Ahmad et al. 2009). After 203 d of cultivation, the chlorophyl content was slightly changed under the T2 treatment compared with the CK treatment, while chlorophyl a, chlorophyl b and carotenoid contents were obviously increased by 20.8%, 44.1% and 28.3%, respectively, in the T1 treatment, which might explain the increase in the plant growth rate. Thus, the chlorophyl content in P. orientalis leaves could be slightly stimulated by a lower level of Cd in the soil, which is consistent with the chlorophyl a and b contents in Vetiveria zizanioides leaves, which reached the highest level at 1 mg/L of Cd treatment in hydroponic experiments (Aibibu et al. 2010). The ratio of chlorophyl a/b was used to evaluate the senescence of leaves (Nie et al. 2016). During the whole cultivation period, the ratio of chlorophyl a/b was slightly changed in the T1 and T2 treatments compared to the CK treatment, while it slightly declined along with plant growth. The reason may be due to sample time; the weather turned cold after 203 d of cultivation, and the leaves of P. orientalis started aging. Therefore, from the level of photosynthesis, P. orientalis possessed a high tolerance to Cd when the soil Cd content was less than 24.6 mg·kg−1.