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Question
In tissue culture, which of the following combinantions of growth hormones need to be added to induce shoot growth?
In tissue culture, which of the following combinantions of growth hormones need to be added to induce shoot growth?
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Solution
The correct option is C Higher concentration of cytokinin and lower concentration of auxin
Tissue culture is a technique used in modern plant breeding for the faster vegetative multiplication (micropropagation) of plants. It is the technique of growing plant cells, tissues or organs in a sterile culture medium under controlled environmental conditions.
In tissue culture, a solid medium is used to grow the explant (plant part/tissue/organ being cultured). Agar agar is used as the solidifying agent. The culture media contains all necessary nutrients such as inorganic salts (for growth), sugars (for energy), amino acids (for protein formation), vitamins (for proper growth and growth hormones (auxins, gibberellins and cytokinins - for differentiation of tissues).
In tissue culture under the influence of the equal concentrations of auxin and cytokinin, the cells of the explant start dividing mitotically and form a mass of undifferentiated cells known as the callus in the beginning. The cells of the callus are totipotent (capable of dividing into any cell type and growing into an entire organism). Hence option d is incorrect.
The callus can be induced to develop roots or shoots by altering the concentration of the growth hormones in the media. Shoot formation is induced with high cytokinin and low auxin concentration in the medium. So option c is correct.
Alternatively, when the newly formed shoot is subjected to a culture media consisting of high auxin and low cytokinin concentration, root formation is induced. Such miniature plants with roots and shoot are called plantlets. So option b is incorrect.
When the callus is put in a culture media that contains only a single hormone, that is auxin, the formation of a somatic embryo is induced. An embryo that can be developed from a single somatic cell is known as a somatic embryo. Each somatic embryo can develop into a plantlet.
When the callus is put in a culture media that contain only cytokinin can lead to the formation of mass of undifferentiated cells. It cannot lead to the formation of an embryo. Hence option a is incorrect.
Tissue culture is a technique used in modern plant breeding for the faster vegetative multiplication (micropropagation) of plants. It is the technique of growing plant cells, tissues or organs in a sterile culture medium under controlled environmental conditions.
In tissue culture, a solid medium is used to grow the explant (plant part/tissue/organ being cultured). Agar agar is used as the solidifying agent. The culture media contains all necessary nutrients such as inorganic salts (for growth), sugars (for energy), amino acids (for protein formation), vitamins (for proper growth and growth hormones (auxins, gibberellins and cytokinins - for differentiation of tissues).
In tissue culture under the influence of the equal concentrations of auxin and cytokinin, the cells of the explant start dividing mitotically and form a mass of undifferentiated cells known as the callus in the beginning. The cells of the callus are totipotent (capable of dividing into any cell type and growing into an entire organism). Hence option d is incorrect.
The callus can be induced to develop roots or shoots by altering the concentration of the growth hormones in the media. Shoot formation is induced with high cytokinin and low auxin concentration in the medium. So option c is correct.
Alternatively, when the newly formed shoot is subjected to a culture media consisting of high auxin and low cytokinin concentration, root formation is induced. Such miniature plants with roots and shoot are called plantlets. So option b is incorrect.
When the callus is put in a culture media that contains only a single hormone, that is auxin, the formation of a somatic embryo is induced. An embryo that can be developed from a single somatic cell is known as a somatic embryo. Each somatic embryo can develop into a plantlet.
When the callus is put in a culture media that contain only cytokinin can lead to the formation of mass of undifferentiated cells. It cannot lead to the formation of an embryo. Hence option a is incorrect.
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