PLANT MORPHOGENESIS AND ORGANOGENESIS Flashcards
_____ The development of a plant’s form and structure through growth and cell differentiation.
_____ The formation of organs (roots, shoots, flowers) either directly from an explant or from callus culture in a controlled environment.
Morphogenesis
Organogenesis
______ Plant growth is regulated by genetic programs and environmental factors.
______ is controlled at multiple levels including genomic regulation (DNA methylation, chromatin remodeling), transcriptional regulation, RNA processing, translational control, and post-translational modifications.
Genetic Control
Gene Expression
Internal signals (hormones) and environmental cues (temperature and day length) trigger the expression of ______ which enable the conversion of the
____ (VEGETATIVE DEVELOPMENT) into the _____ (REPRODUCTIVE DEVELOPMENT)
meristem identity genes
SAM
inflorescence meristem
_____ regulate gene expression, often in response to environmental stimuli.
_____ Essential endogenous chemicals regulate various aspects of plant growth and development
Plant hormones
Phytohormones
List of phytohormones (8)
auxin
cytokinin
gibberellins (GAs)
abscisic acid (ABA)
ethylene
brassinosteroids (BRs)
jasmonic acid (JA)
_____ A single hormone can regulate diverse cellular processes, and multiple hormones can influence a single developmental process.
Complex Regulation
Plant Development Processes:
______ Located at the growing tips of plants, responsible for producing root and shoot tissues.
______ Initiate leaves during vegetative development, and ______and ______ during reproductive phases.
The transition from SAM to inflorescence meristem (IM) is triggered by meristem identity genes influenced by environmental factors like temperature and day length.
_____ Factors like temperature and day length influence meristem identity genes, determining the transition from shoot apical meristem to inflorescence meristem.
Apical Meristems
Shoot Apical Meristems (SAM)
inflorescence Meristem (IM)
floral meristems (FM)
Environmental Influence
Floral Development
Flowers develop from the _____ and consist of (4)
(outermost whorl)
(petals)
(stamens)
(one or more carpels)
floral meristem
Calyx
Corolla
Androecium
Gynoecium
The pistil, which is part of the gynoecium, develops in from the _____.
it consists of stigma, style, and ovary.
In pistil, there is ovary , in that there is one or more _____ which have ____ the place where ovules develop
carpel primordia
carpels
locules
Ovule and Embryo Sac Development:
Ovule development initiates with meiosis in a _____, forming a _____ of megaspores, from which one survives to develop into the embryo sac.
_____ with (2n) megaspore mother cell
_____ Megasporangium with tetrad of (1n) megaspores
Three will be aborted with one megaspore remaining.
_____: The remaining megaspore will form the 8 haploid (1n) nuclei of the embryo sac
megaspore mother cell
tetrad
Megasporangium
Meiosis
Mitosis
Ovule and Embryo Sac Development:
The embryo sac consists of _____,
forming structures such as the:
_____ the female gamete in plants, essential for fertilization
_____ specialized cells in the female gametophyte of flowering plants that guide the pollen tube to the egg cell during fertilization.
_____ two nuclei in the center of the female gametophyte that fuse with a sperm nucleus during double fertilization to form the triploid endosperm.
_____ cells in the female gametophyte located at the opposite end of the embryo sac from the egg cell, thought to have a role in nourishing the developing embryo.
eight haploid nuclei
egg cell
2 synergid cells
2 polar nuclei
3 antipodal cells
Sperm Development:
Gametes of flowering plants are not the direct products of meiosis. Instead sperm cells are formed after two additional mitotic cell divisions creating (3)
three-celled male gametophyte
the pollen
pollen tube
Fruit Development:
Tomato (_____) is used as a model for studying fleshy fruit development.
Stages of Fruit Development (3)
Solanum lycopersicum
- cell division
- cell expansion
- fruit ripening
Fruit Development, Cell Division::
Initial Stage: Follows fertilization, leading to an increase in _____ cell number.
Duration: Lasts for about _____ post-pollination, marked by rapid cell division.
Key Process: ____ is critical for cell division and expansion.
pericarp
two weeks
Sterol production
Fruit Development, Cell Expansion:
Second Stage: Fruit growth is primarily due to ____
_____ The fruit turns into the green stage during this phase.
cell expansion
Mature Green Stage (MG)
Fruit Development, Fruit Ripening:
______ Includes elaborate metabolic changes.
_____ Initial phase of ripening.
______ Final phase where the fruit reaches full maturity.
______ Most widely used external index of tomato maturity.
Final Stage
Breaking Stage
Ripening Stage
Skin Color Change
Hormonal Regulation:
Key hormones involved in fruit set, growth, maturation, and ripening (4)
Seeds produce _____ and _____ to stimulate fruit growth.
_____ Plays a significant role in the ripening of climacteric fruits like tomatoes.
primary hormones governing the fruit maturation phases (3)
Auxin, GA, CK, ABA
auxin
CK
Ethylene
Auxin, CK, ABA
Types of Fruits:
_______: Ripen After Harvest: Includes fruits like avocados, bananas, tomatoes. Can ripen by placing in warmth or exposing them to other climacteric fruits.
_____, in crosstalk with auxin, controls ripening.
Climacteric Fruits
Ethylene
Types of Fruits:
______ Do Not Ripen After Harvest: Includes citrus fruits, cherries, strawberries. Must ripen on the tree; they begin to dehydrate once harvested.
____ has a stronger role during ripening by up-regulating ethylene biosynthesis genes.
Non-Climacteric Fruits
ABA
Cell Wall in Plant Development
Structure and Function:
______ acts as a cellular “exoskeleton” that controls cell shape and allows high turgor pressures to develop.
_____ controlled by cell wall, essential for plant rigidity and growth.
_____ resist collapse due to negative pressure in the xylem, facilitating water transport
____ limiting the size of molecules reaching the plasma membrane and protecting against pathogen invasion.
Cell wall
Turgor pressure
water flow
diffusion barrier
Cell Wall in Plant Development
Cell Wall Architecture:
______ Formed by growing cells, relatively unspecialized and flexible.
______ Form after cell growth ceases, thicker, and more specialized, providing additional strength.
Primary Walls
Secondary Walls
Cell Wall in Plant Development
Composition:
______: Made of cellulose, hemicellulose, and pectin. (during cytokinesis)
_____: Contains lignin, cellulose, and other strengthening compounds. (after expansion ceases)
Primary Wall
Secondary Wall
Cell Wall in Plant Development
Types of Cells:
______: Thin primary walls, involved in metabolic functions.
______: Thickened primary walls, provide flexible support.
______: Thick secondary walls, provide rigid support.
Parenchyma Cells
Collenchyma Cells
Sclerenchyma Cells
Cell Wall in Plant Development
Patterns of Cell Expansion:
______: Localized growth at the cell tip, seen in root hairs and pollen tubes.
______: Uniform growth over the cell surface, common in most plant cells.
Tip Growth
Diffuse Growth
Cell Wall in Plant Development
Role of Hormones:
______: Regulate cell wall loosening and expansion.
activates _____, lowering pH and loosening cellulose fibers.
______: Influx of water into vacuoles increases cell size.
Auxin and Gibberellin
proton pumps
Cell Elongation
_____ transports sugars and other items
_____ transports water and minerals
Phloem
Xylem
