1) Male sterility refers to plants that produce nonfunctional pollen grains and was first reported in cotton in 1960. 2) There are three types of male sterility in cotton: genetic, cytoplasmic, and cytoplasmic-genetic. 3) Hybrid seed production in cotton uses a male sterile A-line, a maintainer B-line to multiply the A-line, and a restorer R-line to restore fertility and produce F1 hybrid seeds when crossed with the A-line.

1. Male sterility:
Cost effective hybrid seed production in
cotton
Presented By: Nouman Bilal
2018-GU-1291
Supervisor: Dr. Wajid Nazeer
Seminar PBG-795, Ghazi University, DG Khan

2. Male sterility
• Male sterility refers to a condition in which nonfunctional pollen grains are
produced in flowering plants.
• In flowering plants, the first case of male sterility was reported by koelreuter in
1763.
• The first case of male sterility was reported by Justus and leinweber in 1960 in
upland cotton (Gossypium hirsutum L.).
Types of male sterility
• Genetic male sterility,
• Cytoplasmic male sterility,
• Cytoplasmic genetic male sterility.
In cotton, all three types of male sterility are found.

3. Genetic Male Sterility (GMS)
• The pollen sterility that is caused by nuclear genes is termed as genic or
genetic male sterility.
• It was first reported in G.hirsutum L. by Justus and Leinweber in 1960.
• Usually governed by one or two recessive genes rarely by dominant
genes.
• In G.arboreum L. Genetic male sterility identified is governed by single
recessive gene. In G.hirsutum L. is governed by two recessive genes
• ms14 and ms5ms6 are being utilized for hybrid seed production of
cotton in India and China.

4. Drawback of Using GMS
• The cross-population segregates into male sterile and male fertile plants.
So, 50% of male fertile plant have to rogue out every year.
• Male sterile and fertile can be identified after anthesis.
• Sometimes sterility broken due to Temperature/Photoperiod fluctuation.
Possible Solution
• One way to overcome this is to sow two or three seeds per dibble and
fertile plants thinned out at the flowering stage to ensure that enough
male sterile plants are left.
• Identification of Male fertile and Sterile plant can overcome by use of
marker gene closely linked to male sterility.

5. Cytoplasmic Male Sterility (CMS)
• It occurs due to the involvement of non-nuclear genes.
• It was first reported by Mayer in 1961.
Feature
• Governed by Plasmic Genes i.e., Mitochondria and Chloroplast.
• Well suited for vegetatively propagated crops where grain yield is not
concern.
• Highly stable to environmental changes.

6. Cytoplasmic Genetic Male Sterility
• A combination of both nuclear genes and cytoplasmic genes determine
the fertility or sterility.
• The CMS line of G. harkensii cytoplasm is highly stable and fertility
restoration and widely used for hybrid seed production.
Drawback of using CGMS
• Transfer of undesirable characters along with sterile cytoplasm.
Possible solution
• Problem of fertility restoration and undesirable cytoplasmic effect could
be overcome through use of genetic male sterility.

7. Hybrid seed production
• There are two steps involve.
Maintenance of parental lines
A-Line ( Female)
B-Line (Maintainer line)
R-Line (Male line, Restorer Line)
• Commercial Hybrid seed production
(A x R)
A-Line B-Line
X
Male Sterile
Male Fertile
A-Line R-Line
Male Sterile Male Fertile
X
Hybrid Seed F1

8. A-Line May Be
• Cytoplasmic Male sterile
• Genetic Male Sterile
• Cytoplasm-Genetics Male sterile
A line can be maintained by crossing with
B-line
A-Line X B-Line
A-Line
While for hybrid seed production
A-Line R-Line
X
F1 Hybrid

9. Desirable characteristic of A-Line
• Absence of pollen grain
• Abortive Anther ( if anther present it should be
empty and non-functional)
• Stable male sterility
• Strongly restored

10. B-Line
• Isogenic line of A
• Only difference is Male sterility
Known as Maintainer line
i. Maintain sterility in A-Line
ii. Multiplication of A-Line
iii. Used as Pollen parent
B-Line can be Maintain through Selfing
B-Line
Selfing
B-Line

11. Characteristic of B-Line
• Well developed floral traits with large pollen load
• Functional Pollen
• Seed setting on Selfing
• Good Combing ability
A-Line B-Line
x
A-Line
Male Sterile

12. R-Line
(Restorer Line)
• R-Line is Male Line
• Possess fertility restoration gene
• R-Line play important role in
increasing heterosis.

13. R-Line can be maintained
R-Line
R-Line
Selfing
Commercial Hybrid
A-Line
Male sterile
R-Line
Male Fertile
X
F1 Hybrid

14. Desirable
Characteristic
of R-Line
• Normal anther , functional pollen
• Strong and stable restoration over
seasons and location
• Complete dehiscence of anthers
• Good outcrossing and combining
ability