This document discusses environmental sensitive genetic male sterility (EGMS) systems for hybrid seed production. It defines male sterility and describes different types of male sterility including genetic male sterility (GMS) such as thermo-sensitive GMS (TGMS) and photo-period sensitive GMS (PGMS). TGMS lines are sterile at particular high temperatures during microsporogenesis, while PGMS lines are sterile under long day conditions. The document outlines the procedure for utilizing TGMS/PGMS lines in hybrid seed production and lists advantages and disadvantages of the EGMS system.

1. ENVIRONMENTAL SENSITIVE
GENETIC MALE STERILITY
Presented by
GOKULAN D

2. Male Sterility
• Male sterility is characterized by nonfunctional pollen grains, while female
gametes function normally.
• Inability to produce or to release viable or functional pollen as a result of failure of
formation or development of functional stamens, microspores or gametes.
• Main reason is mutation.
Sterile Fertile Sterile Fertile

3. Manifestations of Male Sterility
• Absence or malformation of male organs.
• Failure to develop normal microsporogenous tissue- anther.
• Abnormal microsporogenesis (deformed or inviable pollen).
• Abnormal pollen maturation.
• Non dehiscent anthers but viable pollen.

4. History of Male Sterility
• J.K. Koelreuter (1763) observed anther abortion within species & species
hybrids.
• Genic male sterility has been reported in cabbage (Rundfeldt 1960), cauliflower
(Nieuwhof 1961)
• Male sterility systems have been also developed through genetic engineering
(Williams et al. 1997) and protoplast fusion (Pelletier et al. 1995)
• Male sterility were artificially induced through mutagenesis (Kaul 1988)

5. Why Male Sterility ???
• Reduced the cost of hybrid seed production.
• Production of large scale of F1 seeds.
• Avoids enormous manual work of emasculation and pollination.
• Speed up the hybridization programme.
• Commercial exploitation of hybrid vigour.

6. Creation of Male Sterility
• Spontaneous mutations
• Interspecific hybridization
• Mutation induction (EtBr)
• Genetic Engineering
• Chemically induced male sterility (CHAs)

7. Detection of Male Sterility system
• Whether a particular sterile genotype belongs to which MS system can be
detected by its progeny performance on crossing with a few normal genotypes.
• Trend-I- All progenies in all the rows may be sterile- CMS
• Trend-II- Some rows may consist all fertile
Some rows sterile and fertile in 1:1 ratio- GMS
• Trend-III- sterile plant produces all fertile progeny when crossed with restorer -
CGMS

8. Classification of Male Sterility
Kaul (1988) Classified Male Sterility in three major groups
1. Phenotypic Male Sterility (Morphological)
• Structural or Staminal Male Sterility
• Pollen Male Sterility
• Functional Male Sterility
2. Genotypic Male Sterility
• Genetic Male Sterility (GMS)
 Environmental Sensitive (EGMS)
a) Thermo sensitive genetic male sterility (TGMS)
b) Photoperiod sensitive genetic male sterility (PGMS)
 Environmental non-sensitive
• Cytoplasmic Male Sterility (CMS)
• Cytoplasmic Genetic Male Sterility (CGMS)
• Transgenic Male Sterility (TMS)
3. Chemically Induced Male Sterility (CHA)

9. Genetic Male Sterility (GMS)
• Also called as nuclear male sterility.
• Mostly governed by single recessive gene (ms) but dominant gene governing male
sterility (safflower).
• Origin: Spontaneous mutation or artificial mutations (Gamma rays, EMS) are
common.
• ‘ms’alleles may affect staminal initiation, stamen or anther sac development, PMC
formation, meiosis, pollen formation, maturation and dehiscence.

10. Types of GMS
• Environment insensitive GMS: ms gene expression is much less affected by the
environment.
• Environment sensitive GMS: ms gene expression occurs within a specified range
of temperature and /or photoperiod regimes (Rice, Tomato, Wheat etc.).

11. Thermo sensitive Genetic Male Sterility(TGMS)
• Sterility is at particular temperature e.g. In rice TGMS line (Pei- Ai645) at 23.3˚C
(China).
• TGMS at high temperature is due to failure of pairing of two chromosomes at
metaphase was evident.
• This abnormality led to abnormal meiosis, abnormal or sterile pollens.
• Anthers were shriveled and non-dehiscence-Male sterile.
• However, these lines produced normal fertile pollen at low temp.
Sensitive period : PMC formation to Meiosis

12. Photoperiod sensitive genetic male
sterility(PGMS)
• Governed by 2 recessive genes.
• Sterility is obtained in long day conditions while in short days, normal fertile
plant.
• Rice:- Sterile under Long day conditions (13 hr. 45 min + Temp. 23- 29˚C) but
fertile under short day conditions.
Sensitive period: Differentiation of secondary rachis branches to PMC formation

13. Procedure of utilization of TGMS/PGMS line
in Seed production

14. EGMS system in Rice hybrid seed production
• Male sterility system is controlled by nuclear gene expression, which is influenced
by environmental factors such as temperature (TGMS), daylength (PGMS), or
both (TPGMS).

15. Advantage & Disadvantage of EGMS based
hybrid rice system
Advantages
• Simplified procedure of hybrid seed production
• Multiple and diverse germplasm available as parents
• Any line could be bred as female
97% (2-line) vs 5% (3-line) of germplasm as male
• Increased chance of developing desirable & heterotic hybrids
Disadvantages
• Environmental effect on sterility could cause seed purity problem

16. List of TGMS lines in Rice

17. List of PGMS lines in Rice

18. Reference
• Singh, B, D.(2012). Plant Breeding , Principles and Methods. Chapter 6,90.
• https://s3.amazonaws.com/ppt-download/sambhajiyamgar2
170807095824.pdf