Plant physio

    Cards (39)

    • Cytokinins
      A class of plant hormones, synthesized predominantly in the roots of plants, with significant activity occurring in the root tips and vascular tissues
    • Synthesis of cytokinins
      Multistep biosynthesis pathway primarily in root tissues, involving conversion of adenine derivatives like ATP into active cytokinin forms like isopentenyladenine and trans-zeatin
    • Ethylene
      A plant hormone/growth regulator, synthesized in ripening fruits and tissues undergoing senescence
    • Biosynthesis of ethylene
      From S-adenosyl-l-methionine (SAM) via 1-aminocyclopropane-1-carboxylic acid (ACC) synthase and ACC oxidase
    • Abscisic acid (ABA)
      A sesquiterpenoid plant hormone
    • Molecular structure of ABA
      • 15-carbon backbone derived from carotenoids, contains carboxylic acid group and cyclohexene ring
    • Biosynthesis of ABA
      Initiated in chloroplasts, completed in cytosol, involving conversion of glyceraldehyde-3-phosphate and pyruvate to isopentenyl pyrophosphate and then to xanthoxin, which is exported to cytosol and converted to ABA
    • Methods of ABA detection
      • Chromatography techniques like HPLC and GC-MS
      • Immunoassay methods like ELISA
      • Biosensor technologies utilizing ABA receptors or responsive elements
    • Catabolism of ABA
      Oxidation to phaseic acid, further metabolization to dihydrophaseic acid and conjugation with sugars
    • Translocation of ABA
      Synthesized primarily in leaves, fruits, and root caps, transported via xylem and phloem to other plant parts, especially under water stress conditions
    • Types of plants based on photoperiod
      • Short-day plants
      • Long-day plants
      • Day-neutral plants
    • Perception of photoperiodic stimulus
      Leaves perceive the photoperiodic stimulus, produce a floral hormone that is translocated to the apical tip to initiate flower development
    • Critical photoperiod
      Minimum duration of light required to induce flowering, perceived by photoreceptors like phytochromes and cryptochromes
    • Florigens
      Proteins capable of inducing flowering time in angiosperms, produced in leaves and act in shoot apical meristem
    • Gibberellins
      Plant hormones that regulate processes like stem elongation, germination, dormancy, flowering, flower development and leaf and fruit senescence
    • Critical photoperiod
      The minimum duration of light required to induce flowering
    • Photoreceptors in plants
      • Phytochromes and cryptochromes perceive the light stimulus and produce signals that regulate flowering based on the critical length of photoperiod
    • Biloxi soybean variety

      • Short-day plant that flowers when the day length is shorter
    • Maryland Mammoth tobacco
      • Long-day plant that flowers during shorter days
    • Florigens (or flowering hormone)

      Proteins capable of inducing flowering time in angiosperms
    • Prototypical florigen
      Encoded by the FT gene and its orthologs in Arabidopsis and other plants
    • Florigens
      • Produced in the leaves, and act in the shoot apical meristem of buds and growing tips
    • Gibberellins (GAs)

      Plant hormones that regulate various developmental processes, including stem elongation, germination, dormancy, flowering, flower development, and leaf and fruit senescence
    • Phytochromes
      A class of photoreceptor proteins found in plants, bacteria and fungi that respond to light in the red and far-red regions of the visible spectrum
    • Phytochromes
      • Can be classed as either Type I, which are activated by far-red light, or Type II that are activated by red light
    • Vernalization
      A process in which plants require exposure to prolonged cold temperatures to initiate or accelerate flowering
    • Vernalization is particularly crucial for biennial and winter annual plants to ensure they flower in the appropriate season
    • Vernalization
      • Helps plants synchronize their reproductive cycles with favorable environmental conditions, typically occurring in spring
      • Involves molecular changes in the plant's cells, including alterations in gene expression related to flowering
    • Devernalization
      The reversal or inhibition of vernalization due to exposure to warmer temperatures after the cold period
    • In most species the effect of a vernalizing cold treatment can be partially or totally eliminated by several days of heat treatment, typically 30–40 °C (devernalization)
    • Devernalization
      • Can lead to delayed or inhibited flowering, affecting the plant's reproductive success and timing
      • Certain genetic and environmental factors can influence the extent of devernalization and its impact on flowering
    • Cold tolerance of plants
      A plant's ability to survive and thrive in cold temperatures
    • Cold-tolerant plants

      • Often have mechanisms to continue growing even in chilly conditions, such as adjusting their metabolism to function efficiently at lower temperatures
    • Seed dormancy
      A state of inhibited growth and metabolism in viable seeds, which prevents them from germinating even under favourable conditions
    • Types of seed dormancy
      • Physiological dormancy
      • Physical dormancy
      • Morphological dormancy
      • Combined dormancy
    • Germination
      1. Water uptake
      2. Activation of metabolic pathway
      3. Radicle emergence
      4. Cotyledon emergence
      5. Shoot development
    • Bud dormancy
      The period when buds of perennial plants cease growth and remain inactive, typically during winter or unfavorable conditions
    • Methods of breaking bud dormancy
      • Chilling treatment (cold stratification)
      • Photoperiod
      • Utilizing growth-promoting hormones
      • Altering temperature conditions
    • Reasons for bud dormancy
      • Environmental stress
      • Seasonal changes
      • Genetic regulation
      • Resource allocation
      • Protection from damage
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