Flowering in plants(Arabidopsis) ABC Model
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The document discusses the genetic regulation of flowering in plants, specifically focusing on the ABC model of floral organ development, which involves class 'a', 'b', and 'c' genes acting in different floral whorls. It also highlights the roles of key regulatory genes such as apetala1 and leafy, as well as the implications of mutations in these genes on floral structure. The information is contextualized within the study of Arabidopsis mutants and various experimental questions related to plant genetics.
Flowering in plants(Arabidopsis) ABC Model
- 2. Flowering genes Floral meristem identity genes Floral organ identity genes LEAFY (LFY) APETALA1 (AP1) CAULIFLOWER(CAL) APETALA1 (AP1) APETALA2 (AP2) APETALA3 (AP3) PISTILLATA (PI) AGAMOUS(AG) Early stages Transcription factors
- 3. FLORAL PATHWAY INTEGRATORS Gibberellic acid LEAFY Photoperiodic pathway Constans CO FT gene FT protein translocation FD protein LEAFY Autonomous pathway FLC Vernalization Vegetative meristem Flowering meristem
- 4. ABC Model
- 5. Class of genes Gene names Development A APETALA1 (AP1) APETALA2 (AP2) Whorls 1 & 2 B APETALA3 (AP3) PISTILLATA (PI) Whorls 2 & 3 C AGAMOUS(AG) Whorls 3 & 4 Sepals Petals Stamens Carpels HOX genes with MADS domain instead of homeodomain found in humans!
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- 10. 04 ABCDE Model
- 11. Floral organ development is controlled by overlapping expression of ‘A’ class, ‘B’ class and ‘C’ class genes in different whorls. In an Arabidopsis mutant, the flowers had sepals, sepals, carpels & carpels in four whorls. Mutation in which one of the following is the cause of a mutant phenotype? a. Class ‘A’ gene alone b. Class ‘B’ gene alone c. Both Class ‘A’ & ‘B’ genes d. Class ‘C’ gene alone DEC 2015
- 12. Individual and overlapping expression of homeotic genes in adjacent whorls of a flower determine the pattern of floral organ development. In an Arabidopsis mutant, floral organs are distributed as follows: Whorl 1- carpel, Whorl 2- stamens, Whorl 3- stamens, Whorl 4-carpel Loss of function mutation in which one of the following genes would have caused the above pattern of floral organ development a. APETALA 2 b. APETALA 3 c. PISTILLATA d. AGAMOUS DEC 2016
- 13. JUNE 2016
- 14. Which one of the following statements about LEAFY(LFY), a regulatory gene in A. thaliana is correct? a. LEAFY is involved in floral meristem identity b. LEAFY is involved in leaf expansion c. LEAFY is involved in root meristem identity d. LEAFY is responsible for far-red light mediated seedling growth 2015 JUNE
- 15. Which of the floral whorls is affected in apetala3/pistillata(ap3/pi) mutants? a. Sepals and petals b. Petals and stamens c. Stamens and carpels d. Sepals and stamens 2013 JUNE
- 16. Organ identity genes are responsible for correct positioning of floral organs on floral meristem. Mutation in them will lead to? a. Loss of organs from certain whorls b. More number of organs in certain whorls c. Appearance of organs at incorrect positions d. No flower 2009 JUNE
- 17. Photoperiodic stimulus from leaves to shoot apical meristem/ floral meristem is transported through: a. Xylem b. Phloem c. Plasmodesmata d. Apoplast 2008 JUNE
- 18. Among the following which gene product migrates from leaves to shoot meristem during transition of shoot meristem into floral meristem? a. Flowering locus T b. Flowering locus D c. leafy d. apetala 1 2010 DECEMBER
- 19. Three classes of genes A, B & C regulate the development of flower in Arabidopsis. If a loss of function mutation occurs in the type B genes, what will be the composition of flower whorls? a. Sepals-Petals-Stamens-Carpels b. Sepals-Sepals-Stamens-Stamens c. Sepals-Sepals-Carpels-Carpels d. Petals-Petals-Stamens-Stamens DEC 2009
- 20. The control of flowering is a complex process involving several key regulatory genes. Some statements on flower development are given below: A. Two major types of genes regulate floral development: meristem identity & floral organ identity genes B. The important genes in Arabidopsis that play key regulatory roles in meristem identity are: APETALA1, LEAFY and SUPPRESSOR OF CONSTANS 1 C. The genes that determine floral organ identity were discovered as floral homeotic mutants D. Most plant homeotic genes belong to a class of related sequence known as FAD box genes Which of the following combinations is correct? a. A, B and C b. B, C and D c. A, C and D d. A, B and D DEC 2013