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#cytokinin

10 public questions tagged with this topic.

Plant tissue culture 1

High auxin and low cytokinin ratio promotes:

High auxin coupled with low cytokinin specifies root regeneration from callus or shoots, principle underlying rooting stage of micropropagation and natural adventitious rooting of cuttings. Elevated auxin synthesized via TAA1/YUCCA and transported acropetally creates maximum at basal region where founder cells are specified. Auxin binds nuclear receptors TIR1/AFB forming SCF complex that ubiquitinates Aux/IAA repressors for 26S proteasome degradation, freeing ARF7 and ARF19 to transcribe LBD16, LBD18, LBD29 and PLETHORA family genes converting pericycle-like parenchyma into root primordia. Aux

Ref: Perianez-Rodriguez et al., Front Plant Sci 2014 auxin root specification; Taiz & Zeiger Chap. 19.

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Plant tissue culture 1

Low auxin and high cytokinin ratio promotes:

Low auxin combined with high cytokinin directs differentiation toward shoot regeneration, fundamental to shoot multiplication media. Cytokinin dominance activates signaling cascade: cytokinin binding to sensory histidine kinases AHK2, AHK3, AHK4 in endoplasmic reticulum triggers histidine-to-aspartate phosphorelay via AHPs to nucleus where type-B ARR transcription factors ARR1, ARR10, ARR12 switch on genes for shoot meristem identity. Key targets include WUSCHEL maintaining stem cell pool, SHOOT MERISTEMLESS KNOX gene preventing differentiation and CYCD3;1 promoting cell cycle in peripheral zo

Ref: Campbell Biology Chap. 39; Teale et al., Nature Rev Mol Cell Biol 2006 auxin-cytokinin crosstalk.

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Plant tissue culture 1

Intermediate auxin : cytokinin ratio induces:

The concept of auxin cytokinin interaction governing morphogenesis was established by Skoog and Miller using tobacco pith cultures, showing distinct concentration ratios produce different developmental outcomes. Intermediate ratio where both hormones are present in approximately equal proportions sustains cell division without organ determination, leading to formation of unorganized callus mass. Mechanistically balanced signaling maintains expression of D-type cyclins particularly CYCD3;1 and cyclin dependent kinases driving G1 to S transition while preventing dominant activation of shoot prom

Ref: Skoog & Miller 1957; NCERT Class XI Biology, Chap. Plant Growth, tissue culture.

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Cytokinin

Low cytokinin:auxin ratio promotes:

The right choice is B: Root formation. In Cytokinin, that matches how the process or concept actually works — the other choices mix up related ideas or use the wrong mechanism. Skip these: A) Shoot formation; C) Callus growth; D) Flowering. A quick check: if an option needs energy, pumps, or the opposite direction of movement, ask whether that really applies.

Ref: Best CSIR NET Plant Physiology books: Master Unit 6 with Taiz & Zeiger and Salisbury & Ross. Crack Part C experimental questions with top textbooks.

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Cytokinin

High cytokinin:auxin ratio in tissue culture promotes:

Correct option is C, Shoot formation. In Cytokinin problems like this, the accurate statement is Shoot formation; the others are common mix-ups. Not these: A) Root formation; B) Callus formation; D) Somatic embryogenesis. Tissue transport questions usually turn on xylem vs phloem, living vs dead cells, or source vs sink.

Ref: Best CSIR NET Plant Physiology books: Master Unit 6 with Taiz & Zeiger and Salisbury & Ross. Crack Part C experimental questions with top textbooks.

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Striglactone

Cytokinin generally acts as a:

Pick B: Antagonist of SL. Thinking through Striglactone step by step rules out the lookalikes and leaves Antagonist of SL. Skip these: A) Synergist of SL; C) Precursor of SL; D) Receptor of SL. For hormones and genes, match the molecule or gene to its real role, not a neighboring pathway.

Ref: Best CSIR NET Plant Physiology books: Master Unit 6 with Taiz & Zeiger and Salisbury & Ross. Crack Part C experimental questions with top textbooks.

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