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Biotechnology and Flood-Resistant Rice
Published in Saeid Eslamian, Faezeh Eslamian, Flood Handbook, 2022
Saima Aslam, Nadia Gul, Shabana Aslam, Saeid Eslamian
Plants also show little or no elongation to avoid futile energy consumption and save energy for recovery-like processes (Sarkar, 1998; Almeida et al., 2003). Plant growth hormones play a notable role in stem elongation processes. Their effect on seedling survival rate during submergence was elucidated. Application of gibberellic acid biosynthesis inhibitors like paclobutrazol (PB) resulted in increased seedling survival. Moreover, gibberellic acid-deficient mutants showed a higher level of submergence tolerance in comparison with FR13A tolerant ones. Application of PB decreased the elongation along with heightened retention of non-structural carbohydrates (NSC). Also, FR13A was found to be little responsive to PB, showing the inherent potential of reduced concentration of gibberellic acid under submergence. NSC level after submergence is more important than prior submergence indicating the level of carbohydrates being an important factor pertaining to survival after submergence (Das et al., 2005). Reduction in ABA content is also seen in rice plants after submergence, suggesting that those plants do have the SUB1A-1 allele that tends to hinder the gibberellic acid signaling under submergence. The SUB1A-1 leads to increased production of slender rice-1 (SLR1) and slender rice-like proteins (SLRL1) which are potent gibberellic acid inhibitors (Fukao and Bailey-Serres, 2008). SLR1 and SLRL1 proteins tend to get regulated when stimulated by ethylene during submergence (Kawano et al., 2002; Ella et al., 2003). Treatment of 1-methyl cyclopropene (MCP) to tolerant as well as intolerant varieties leads to decreased expression of chlorophyllase gene, deprivation of chlorophyll, and improved survival in intolerant varieties while chlorophyllase gene expression decreased in tolerant varieties (Sone et al., 2011). A comparative study of tolerant varieties with intolerant ones showed that tolerant varieties have reduced leaf and internodes elongation, decreased carbohydrate consumption, and heightened PDC and ADC enzymatic activities than the intolerant (Fukao et al., 2006). According to transgene analysis of SUB1-A1 promoter activity in the inter-nodes, leaf base and collar sites have an important role in suppressing the elongation growth of tolerant plants under submergence stress (Singh et al., 2016).
Effects of paclobutrazol (PP333) on lead and zinc accumulations in Pseudostellaria maximowicziana
Published in Chemistry and Ecology, 2018
Lei Liu, Shuling Zheng, Fabo Chen, Jianhua Li, Ming’an Liao, Lijin Lin, Haoru Tang, Qunxian Deng, Huanxiu Li, Xun Wang, Jin Wang, Yi Tang, Mengyao Li, Huifen Zhang, Huaxiong Li
Paclobutrazol (PP333) is a plant growth regulator that is widely used on agricultural crops and ornamental plants, as well as in tissue culturing. It plays important roles in regulating the hormonal balance of plants, inhibiting stem elongation, increasing crop yield and enhancing the resistance of crops to stress [1,2]. Under drought stress, PP333 (50–400 mg/L) increases the chlorophyll contents and antioxidant enzyme activities and reduces the relative conductivities and free proline contents of six turf grasses (Gramineae family) to enhance their drought resistance, and the best doses are 100–300 mg/L PP333 for different grasses [3]. The dose of 66.7 mg/L PP333 induces the resistance of Olea europaea seedlings to drought stress [4]. Under low temperature, the dose of 2 mg/L PP333 inhibits the increase in the processing of membrane permeability, and enhances the resistance of Euphorbia tirucalli seedlings to freezing cold above 0°C [5]. Under salt stress, PP333 regulates the components of the antioxidant system in plants to enhance the resistance [6,7]. PP333-treated (200–400 mg/L) radish seedlings under salt stress also have increased chlorophyll contents and reduced malondialdehyde contents to alleviate the salt damage [8]. Thus, PP333 treatments can enhance the plant’s resistance to ordinary stresses. Under heavy metal stress, PP333 decreases heavy metal concentrations in maize and sorghum [9,10]. For Cannabis sativa seedlings, PP333 only increases the zinc concentration in plant, and decreases cadmium, lead and copper concentrations in plant [11]. However, for hyperaccumulator plants, the dose of 5 mg/L PP333 increases the chromium concentration in Houttuynia cordata [12]. So, using PP333 on heavy metal hyperaccumulator plants may enhance their resistance to heavy metals, increasing their phytoremediation capabilities.