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Bioprospecting of Microbial Diversity for Sustainable Agriculture and Environment
Published in Vineet Kumar, Vinod Kumar Garg, Sunil Kumar, Jayanta Kumar Biswas, Omics for Environmental Engineering and Microbiology Systems, 2023
Hiren K. Patel, Nensi K. Thumar, Priyank D. Patel, Azaruddin V. Gohil
Cytokinin-synthesizing ability of PGPR was also studied. Cytokinin is required for germination of seed, expansion of leaves, and delay in senescence. It also enhances cell division. Isopentenyladenosine monophosphate is the precursor of cytokinin, which is derived from dimethylallyl phosphate and adenosine monophosphate. The active form of cytokinin is zeatin (Maheshwari et al. 2015). From Coleus, two Pseudomonas, i.e. P. stutzeri and P. putida, and one Stenotrophomonas, i.e. Stenotrophomonas maltophilia,were isolated, which have the potential to synthesize cytokinin (Patel and Saraf 2017). Root cells can absorb more cytokinin in their free form bases, and they can be more accumulated in shoot than root. This shows more rapid export is possible with root-derived ribosides of cytokinin in shoot (Kudoyarova et al. 2019). Pseudomonas sp., Agrobacterium sp., and the genera such as Escherichia, Klebsiella, Proteus, and Xanthomonas were reported to synthesize cytokinin (Maheshwari et al. 2015).
Potential Applications of Plant Growth-Promoting Rhizobacteria in Soil
Published in Gustavo Molina, Zeba Usmani, Minaxi Sharma, Abdelaziz Yasri, Vijai Kumar Gupta, Microbes in Agri-Forestry Biotechnology, 2023
Debosmita Chakraborty, Puneet Kumar Singh, Bhagyashree Puhan, Pratikhya Mohanty, Snehasish Mishra
The phytohormone cytokinin enhances cell division in roots and shoots of plants as well as has a role to play in the growth and differentiation of plants. It also has an effect of senescence of leaves, growth of axillary bud, and apical dominance (Kumar et al. 2019). Considering that cytokinin is a comparatively usual characteristic of PGPR, the selection of bacterial inoculants that produce high levels of cytokinin must be given more consideration for the possible enhancement of the salt stress (Dodd 2004; Kumar et al. 2019). Cytokinin is produced by Bacillus subtilis, which is capable of stimulating biomass of shoot of lettuce plant which grows in soil that is drying. This suggests substantial root-to-shoot signaling of cytokinin (Kumar et al. 2019). For the most part, there is the declination in the root-and-shoot growth and level of cytokinin in tomato plants.
Trailhead
Published in James Barilla, Naturebot, 2021
Like horses and humans and cockroaches, plants need to sample the world via a suite of appropriate senses, and they need to process this incoming information and “decide” how to respond. Thus far, Mazzolai’s team has identified several potentially useful “tropisms,” mechanisms that plants use to sense the world and direct root growth. Gravity is one—plants can sense the gravitational pull of the Earth. Phototropism, or sensing and responding to light, is another; together they allow plants to “know” which way is up toward the sun and which way is down into the soil. Plants typically respond to these stimuli by secreting two key growth hormones, auxin and cytokinin, that govern cell growth and distribution in the root tip. It turns out, however, that even in the zero gravity conditions of the international space station, 240 miles above the Earth, plants are able to compensate using other mechanisms that are still only partially understood.
Roles of phytohormones in mitigating abiotic stress in plants induced by metal(loid)s As, Cd, Cr, Hg, and Pb
Published in Critical Reviews in Environmental Science and Technology, 2023
Zhi-Hua Dai, Dong-Xing Guan, Jochen Bundschuh, Lena Q. Ma
Besides salicylic acid, other phytohormones play a role in controlling the auxin levels under metal(loid)-stress. Among phytohormones, brassinosteroids, cytokinin, gibberellic acid, and salicylic acid can increase the auxin level in plants under metal(loid)-stress. In this case, a decrease in cytokinin levels lowers the auxin levels in plants (Mohan et al., 2016; Ronzan et al., 2018). This is because cytokinin induces the expression of auxin biosynthesis genes to enhance its production, thereby catalyzing the conversion of indole pyruvic acid to auxin in plants (Di et al., 2016; Zhou et al., 2011).