Growth and Development 1 Flashcards
Define development
the sum of all of the changes that plant goes through during its life-cycle
what is the sequence of events required by development (5)
1 Fertilized egg grows–> 2 differentiates into organs (leaves, stems)—>3 juvenile phase (vegetative)—> 4 mature/adult phase (bears flowers, fruits)—> 5 senesces / dies
development is the result of a _______
pre-determined program
define pre-determined program
genetically controlled
Developmental changes (such as flowering, dormancy induction, cold-hardening etc.) result from the \_\_\_\_\_\_ at specific time / period during the life cycle.
expression of specific genes
define epigenetic changes
change does not occur in the basic genotype/gene make-up of plant
define growht
A quantitative term – related to change in size, mass, volume
Growth is an _______ increase in volume or size or the weight* (expanding leaves or fruits)
irreversible
what does plant growth occur due to
cell division and cell elongation
where does cell division take place?
meristems
what growth occurs in Apical meristem
increase in length/height
what growth occurs in lateral meristem
increase in girth (woody, dicot)
what are the meristems of grasses known as
intercallery
define differentiation
Change in the form and function of cells that are produced by cell division (specialization of structure and function)
define de-differentiation
mature cells from a leaf section can be stimulated to reacquire an ability to divide to produce mass of callus cells
define redifferentiation
callus cells then differentiate, i.e. produce shoots and roots in the presence of nutrients and appropriate balance of HORMONES
(auxins and cytokinins)
what does tissue culture medium contain?
carbohydrates, salts, vitamins, hormones (auxins and cytokinins), and AGAR, a gel-like support – sterile environment
what is tissue culture in the horticulture industry used for
rapid multiplication of disease-free, clonal plants
development =
growth + differentiation
what are three ways growth can be measured
fresh weight, dry weight, and relative growth rate
define fresh weight
Weight of a freshly harvested plant / plant part– increase in the FW with time gives a measure of growth
why is fresh weight not always accurate
diurnal and seasonal fluctuations
define dry weight
measure of the dry matter accumulated in
the plant tissue (everything but water)
is dry or fresh weight used more often>
dry
define relative growth rate
relative measure of growth rate
define senescence
final stage of the development of cells, tissues, and organs, the consequence of an aging process
describe senescence seasonally
leaf fall in deciduous shrubs/trees – N is mobilized from these senescing leaves & stored as storage proteins in the bark (Bark
Storage Proteins) that are used for new growth in the spring
what is a form of programmed cell death
senescence
what does PCD stand for
programmed cell death
Plants constantly respond to their environment by sensing cues or SIGNALS such as ________ which all modulate various
developmental processes
light, temperature, gravity, soil moisture
in order for a signal to be effective it must be _____ by the cell
perceived
after a signal is perceived it must be _____ to some change in the cellular environment / chemistry
transduced (converted)
after transduction
there is a response
what involves second messangers
transduction
what is a common second messanger
Ca 2+
______ leaf of bean plant is a SIMPLE leaf while the ______ leaves are COMPOUND
Juvenile and adult
Hormones Can affect physiological processes at exceedingly _____ concentration (ppm, micromolar)
low
what are the 3 effects of pgrs and hormones depend on
- Dosage and Developmental stage 2. environmental conditions and the nutritional status of the plant 3. he responsiveness of the target cell / organ
define pgr
synthetic compounds that mimic hormones
define plant hormone
•Naturally occurring Organic substances
what are the 5 major classes of plant hormones
Auxins, Gibberellins, Cytokinins, Abscisic acid, Ethylene
