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#plant hormone

19 public questions tagged with this topic.

General Biology - Part 3

The chemical nature of GA3 is

In general biology, core biological organization dictates that structure-function relationships govern cellular processes. Therefore Terpene is correct as it integrates fundamental principles, supported by mechanistic studies and conserved across related systems.

Ref: Campbell et al., Biology, 11th Edition, Chapter 2, Chemical Basis of Life, discusses fundamental biological principles and molecular organization providing broad foundation for life sciences understanding.

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Microbiology and Physiology

Aerenchyma formation is related to which of the following hormones?

The principle of bioenergetics and thermodynamics explains that internal energy, enthalpy and pressure-volume work describe evaporation and combustion. Hence Ethylene fits best because it satisfies first law and physiological energetics, as documented in authoritative sources on physiology and thermodynamics.

Ref: Hill, Wyse and Anderson, Animal Physiology, 4th Edition, Chapter 7, Neurophysiology and Thermodynamics, discusses internal energy, enthalpy, work done, P(V2-V1), sweat evaporation and bioenergetics detailing physiological energy balance.

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Transgenic Plant -2

ACC synthase catalyzes conversion of SAM to:

Plant ethylene biosynthesis, termed Yang cycle, converts sulfur amino acid methionine to gaseous hormone ethylene through two committed enzymatic steps plus recycling. Methionine is first activated by SAM synthetase encoded by MAT genes using ATP to form S-adenosylmethionine, universal methyl donor and precursor for polyamines and ethylene. The rate-limiting step is catalyzed by ACC synthase, a pyridoxal 5'-phosphate dependent aminotransferase encoded by multigene family ACS1-ACS12 differentially regulated by auxin, cytokinin, wounding, flooding and fruit ripening cues. ACS cleaves SAM into 1-

Ref: Taiz & Zeiger Plant Physiology 6th ed Ch 22 Ethylene; Yang Cycle review Annu Rev Plant Physiol 1984.

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Plant tissue culture 1

Ethylene differs from other plant hormones because it is:

Ethylene stands unique among classical phytohormones being only gaseous hydrocarbon C2H4 with high diffusivity without need for active transport proteins. Biosynthesis follows methionine to S-adenosyl methionine AdoMet then ACC via ACC synthase ACS multigene family rate limiting, finally oxidation to ethylene by ACC oxidase ACO requiring iron ascorbate oxygen. As volatile it accumulates in sealed culture vessels influencing morphogenesis unless vented. Signaling occurs at endoplasmic reticulum membrane where receptors ETR1, ERS1, ETR2 function as negative regulators; in absence of ethylene the

Ref: Bleecker & Kende Annu Rev Cell Dev Biol 2000 ethylene; NCBI NBK21448 ethylene.

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Plant tissue culture 1

Abscisic acid is known as:

Abscisic acid designated as stress hormone and growth inhibitor originates from carotenoid pathway, cleavage of 9 cis violaxanthin and neoxanthin by NCED dioxygenase to xanthoxin then converted by ABA2 short chain dehydrogenase and AAO3 aldehyde oxidase to ABA. Under drought salinity cold endogenous levels rise sharply triggering PYR PYL RCAR receptor family that sequesters PP2C phosphatases ABI1 ABI2 releasing SnRK2 kinases OST1 to phosphorylate targets including bZIP transcription factor ABI5 inducing late embryogenesis abundant LEA genes, anion channel SLAC1 causing stomatal closure reducin

Ref: Cutler et al., Annu Rev Plant Biol 2010 ABA signaling; NCBI NBK541119 ABA.

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