Table of Contents
How is flowering controlled in Arabidopsis?
In long-day plants, such as Arabidopsis, if the plant is exposed to light at the crucial phase of the rhythm, flowering is promoted.
What are floral organs?
Flowers are typically composed of four organ types, which are disposed in four floral whorls. From the outside of the flower to the center, they are sepals, petals, stamens, and carpels (the subunits of the gynoecium).
What is floral organ identity?
Once FM has been determined, floral organ identity is established from specific meristematic domains, which result in the initiation of sepal, petal, stamen, and carpel primordia in the four whorls forming the flowers of most angiosperms.
What is the ground state of floral organs?
(A) The ground state of floral organs is similar to leaves (here, an Arabidopsis cauline leaf is shown); in different floral whorls, different combinations of organ identity modify the ground-state organ to sepals (B), petals (C), stamens (D), or carpels (E).
What is floral determination?
In contrast with floral induction, floral determination can be defined as the assignment of flower(ing) fate, which is persistent even when the flower-inducing conditions no longer exist8, 9. Assays for floral determination include: Changing environmental conditions (from inductive to non-inductive).
How are flowering plants regulated?
All flowering is regulated by the integration of environmental cues into an internal sequence of processes. These processes regulate the ability of plant organs to produce and respond to an array of signals. The numerous regulatory switches permit precise control over the time of flowering.
What are the four floral organs?
A complete flower is composed of four organs attached to the floral stalk by a receptacle (Figure 11). From the base of the receptacle upward these four organs are the sepals, petals, stamens, and carpels.
What are floral parts of a flower?
Parts of a Flower
- Peduncle: The stalk of a flower.
- Receptacle: The part of a flower stalk where the parts of the flower are attached.
- Sepal: The outer parts of the flower (often green and leaf-like) that enclose a developing bud.
- Petal: The parts of a flower that are often conspicuously colored.
What is the model used to help explain determination of floral organic identity?
The ABCDE model for flower development proposes that floral organ identity is defined by five classes of homeotic genes, named A, B, C, D and E [1].
Why do many plants use the photoperiodic pathway to regulate the timing of flower formation?
Why do many plants use the photoperiodic pathway to regulate the timing of flower formation? Flowering in this plant is controlled by both day length and temperature. The warm room and extended exposure to light are preventing flower formation.
What influences flowering in plants?
There are four primary external environmental cues that affect flowering in plants: photoperiod, temperature, irradiance, and stress (fire, water levels). In addition, lack of stress or supra-optimal levels of nutrients or saturating water levels can also impact progression towards flowering.
What four different whorls of a flower and state their function?
Each of these whorls contains one of the flower organs, the sepals, petals, stamens, or pistils, respectively. Sepals and petals are not directly involved in reproduction, while the stamens and pistils are the male and female reproductive organs.
Is leaf part of a flower?
Leaf. The leaf is the part of the flower responsible for making food for the process of photosynthesis.
Which of the floral organ identity genes are involved in the development of carpels?
The Arabidopsis C-class gene, AtAG, controls the identity of stamens and carpels, but also the determinacy of the flower meristem50, 51.
How do plant genes control the identity of floral organs?
Class A genes, when expressed alone, produce sepals. The expression of classes A and B together directs petal identity. The expression of classes B and C together regulates stamen identity and the expression of Class C genes alone determines carpel identity.
How does the ABC model of flower formation explain the formation of the four types of floral organs?
As discussed above, the floral organs of eudicotyledonous angiosperms are arranged in 4 different verticils, containing the sepals, petals, stamen and carpels. The ABC model states that the identity of these organs is determined by the homeotic genes A, A+B, B+C and C, respectively.