Where does biosynthesis of cytokinins occur?
Most adenine-type cytokinins are synthesized in roots. Cambium and other actively dividing tissues also synthesize cytokinins.
Which biochemical modification causes biosynthesis of cytokinin?
3.7 Cytokinins and Senescence They are synthesized by biochemical modification of adenine and are transported via the xylem from roots and shoots (Davies, 2010).
What is the bioassay of cytokinin?
Cytokinins have the ability to retard the degradation of chlorophyll in excised leaves. Hence, chlorophyll preservation test is a bioassay for cytokinin. Cytokinin promotes cell enlargement in the leaf tissues of certain plants. So, radish and bean leaf test have been used as bioassay.
What is the precursor of cytokinin?
Furfural, a precursor of the cytokinin hormone kinetin, and base propenals are formed by hydroxyl radical damage of DNA.
How is cytokinins transported in a plant?
Different cytokinin species are translocated between different plant organs. trans-zeatin types are transported via the xylem from roots to shoots and isopentenyladenine types via the phloem systemically or from shoots to roots (reviewed in Kudo et al., 2010; Zürcher and Müller, 2016).
Which is main function of cytokinins?
Cytokinins are a group of plant growth regulators which are primarily involved in performing cell division in plant roots, shoot system. This hormone helps in promoting the cell’s growth, development, differentiation, affecting apical dominance and delay in leaf senescence.
How does cytokinin affects the plant development?
Cytokinins are essential plant hormones. By stimulating cell division, they regulate shoot meristem size, leaf primordia number, and leaf and shoot growth. They can stimulate both the differentiation and the outgrowth of axillary buds.
What is bioassay method?
A bioassay is an analytical method to determine the concentration or potency of a substance by its effect on living animals or plants (in vivo), or on living cells or tissues(in vitro). A bioassay may be used to detect biological hazards or to give an assessment of the quality of a mixture.
Which one of the following is synthetic cytokinin?
2,4-5 trichlorophenoxypropionic acid.
How do auxins and cytokinins work together?
In the root meristem, auxin induces the meristematic cell division, whereas cytokinin promotes the cell to switch from the meristematic to differentiated state through inhibiting auxin signaling.
What would happen if cytokinins are applied to a plant externally?
Cytokines act as local growth hormones i.e. It will act on the place it is applied externally. Ethylene is the growth and maturation hormone of the plant. If it is applied to the mango tree, its fruit will mature rapidly. The process of parthenocarpy.
What are the biosynthetic and metabolic pathways of cytokinins?
The key biosynthetic and metabolic pathways of cytokinins are summarized in Fig. 1. The biosynthesis of isoprenoid cytokinins starts with transfer of the isoprenoid moiety to adenine either in its nucleotide forms or bound to RNA.
Is trans-zeatin a source of active cytokinins?
Since it is resistant to degradation by cytokinin dehydrogenase (CKX; Galuszka et al., 2007) it may serve as a source of active cytokinins before the acceleration of de novo biosynthesis after germination. Low levels of trans -zeatin can also be found in tRNA, but in ∼40 times lower amounts than cis -zeatin ( Vreman et al., 1978 ).
Is cytokinin a master regulator of plant growth and development?
Cytokinin has been considered to be a master regulator of plant growth and development, but only in the past several years has substantial progress been made uncovering the roles of cytokinins at various developmental stages.
What are the products of de novo cytokinin biosynthesis?
The initial products of de novo cytokinin biosynthesis in higher plants and Agrobacterium are different, and the regulatory systems in biosynthesis and homeostasis are finely controlled and appear to be important in communicating nutrient signals to morphogenetic responses.