a gene that controls seed dormancy crucial to some plants.

1. Course Code:GEB301
Course Title: Plant Physiology
Course Instructor: Dr. Md. Tofazzal Islam
Genetic Engineering & Biotechnology
Department

2. RICHITA ISLAM(2015-1-77-049)
ZANNATI EVA (2015-2-77-003)
ASMA HOSSAIN (2015-2-77-004)
SYEDA KASHFIA KABIR (2015-2-77-008)

3. The Research Paper At A Glance

4. By Mr. Maofeng Chai & his co-workers
• This was published in PNAS Journal (vol. 113 | no. 25)
• Published Date: June 21 2016
• DOI:10.1073

5. Outlines
• Keywords
• Background of the Research
• Introduction
• Objectives
• Materials and Methods
• Results and Discussion
• Conclusions

6. Keywords
 Seed Physical Dormancy - It is a complex adaptive trait of higher
plants that allows embryos to survive extended periods of
unfavorable environmental conditions.
 Seed Coat:
The outer protective covering of a seed. The seed coat develops from
the ovule. Also called testa.

7. Keywords
 KNOX Gene - A class II KNOTTED-like homeobox (KNOXII) gene,
KNOX4, is responsible for the loss of physical dormancy in the seeds.
 Medicago Truncatula - The barrelclover, strong-spined medick,
barrel medic, is a small annual legume native to the Mediterranean
region that is used in genomic research.

8. Background of this Research
There are 2 types of seed dormancy :-
 Seed Physiological Dormancy which is caused by endogenous factors
(e.g., abscisic acid) in embryos.Most molecular studies on seed dormancy
have focused on physiological dormancy, using model species Arabidopsis
thaliana.
 Seed Physical dormancy is an exogenous dormancy caused by a water-
impermeable hard seed coat. To know the factors behind seed physical
dormancy this research was doe.

9. Introduction
 Physical Dormancy allows plants to maintain a seed bank in soil,
and thus survive unfavorable environmental conditions.
 Using the model legume plant, Medicago truncatula, to study
seed Physical Dormancy because this species produces seeds
with typical physical dormancy.
 The genetic and molecular analyses revealed that a class II
KNOTTED-like homeobox (KNOX) gene, KNOX4, controls
physical dormancy by regulating seed-coat cuticle development.

10. Objectives
 To know the cause behind seed plant evolution from seed.
 To understand the molecular mechanism of physical dormancy.
 To identify mutants with defects in physical dormancy.
 To identify the differences between mutant and wild type seeds.

11. Materials
The essential materials of the research were:
1. Medicago truncatula ecotype R108
2. TAIL-PCR & RT-PCR
3. Optimum temperature :20-22 degree
Celsius(Day/night)
4. Optimum photo period:16-h/8-h (Day/night)
5. Relative humidity 70-80%
Medicago truncatula

12. Methods
Plasmids & Plant Transformation
Lipid Polyester Analysis
GUS Staining
In Situ Hybridization Analysis
RNA Extraction, RT-PCR Analysis
Microscopic Observations of Seed
Coat
Plant Materials & Growth Condition
METHOD

13. Results and Discussion
 Isolation and Characterization of Mutants Without Physical Dormancy.
 Physical Dormancy Is Controlled by KNOX4.
 Expression Pattern of KNOX4.
 Loss of Function of KNOX4 Dramatically Altered Seed Coat Architecture
 Mutation of KNOX4 Altered Seed Coat Cuticle Composition.
 KNOX4 Directly Regulates Cuticle Biosynthetic Genes.
 KNOX4-Like Genes Are Involved in Seed Plants Evolution.

14. Results and Discussion

15. Results and Discussion

16. Results and Discussion

18. Conclusion
 The study of our journal provides an understanding of the molecular
mechanism of physical dormancy and offers a perspective for seed plant
evolution.
 We have showed that M. truncatula is an ideal model for studying
physical dormancy of seeds.
 KNOX4 is a key regulator for seed coat development and controls seed
physical dormancy by affecting downstream cuticle genes.This journal
elucidated a novel molecular mechanism of physical dormancy and
revealed a new role of class II KNOX genes.

19. Thanks to the Authors (Mr. Chai & his co-workers)
Our Respective Course Instructor Dr. Md. Tofazzal Islam
Our Teaching Assistant Effi Haque
& all of our group members 

20. THANK YOU...