Male sterility & its significance in plant

breeding

Submitted by:- Sweety DahiyaClass:- M.Sc. (P) Botany

Roll no. 31

Contents• Introduction• Manifestations of male sterility• More prevalent than female sterility• Classification • Genetic male sterility• Cytoplasmic male sterility in Maize• Fertility restoration in Maize• Chemically induced male sterility• Applications• Significance in plant breeding• References

Introduction• Male sterility:- it is the failure of

plants to produce functional anthers, pollen, or male gametes.

• Occurs mainly in bisexual plants.• J.K. Koelreuter (1763) observed

anther abortion within species & species hybrids.

• More prevalent than female sterility.

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, sporophytic control

• Barriers other than incompatibility preventing pollen from

reaching ovule

More prevalent than female sterility

• Male sporophyte and gametophyte less protected from environment than ovule and embryo sac

• Easy to detect male sterility, because a large number of pollen for study available

• Easy to assay male sterility:- Staining technique (caramine, lactophenol or iodine) Female sterility requires crossing

• Male sterility has propagation potential in nature

Classification of male sterilityPhenotypic

• Three types of sterility:

• “Pollen sterility” in which male sterile individuals differ from normal only in the absence or extreme scarcity of functional pollen grains (the most common and the only one that has played a major role in plant breeding)

• “Structural or staminal male sterility” in which male flowers or stamen are malformed and non functional or completely absent

• “Functional male sterility” in which perfectly good and viable pollen is trapped in indehiscent anther and thus prevented from functioning

Based on its inheritance or origin Cytoplasmic male sterility (CMS) - sterile

cytoplasm (S)• Male sterility comes about as a result of the combined

action of nuclear genes and genic or structural changes in the cytoplasmic organellar genome.

• maternally inherited.

Nuclear male sterility (NMS) - Genic, genetic, mendelian

• Male sterility is governed solely by one or more nuclear genes.

• Nuclear inherited

Non genetic, chemically induced male sterility-

• Application of specific chemical (gametocides or chemical hybridizing agents)

Genetic male sterility• Controlled by a

number of nuclear genes- MALE STERILE GENES.

• Effectiveness of these genes maybe expressed by-

%age of viable pollens.

%age of seed set.• GMS is controlled by

a pair of recessive alleles “msms”.

Flower phenotypes in carrot

• a) Normal (N-cytoplasm, restored CMS plants)• b) Brown anther CMS• c) Petaloid CMS

Cytoplasmic male sterility in Maize(Zea mays)

• Male & female reproductive organs are present on different parts of the plant.

• In 1930s, Rhoades demonstrated that male sterility in Maize can be caused by maternally inherited factor.

• Rhoades pollinated the ears of male sterile strain with the pollen from a male fertile strain.

.

Fertility restoration in Maize

.

Chemically induced male sterility

• It can be done when different growth hormones such as NAA, IAA, Malic hydrazide etc are sprayed on plants before flowering.

e.g Cotton, Wheat, Sorghum etc.• But it is not possible to obtain

complete male sterility by using chemicals.

Applications• Eliminate emasculation in

hybridization.• Increase natural cross-pollination in

self pollinated species.• Controlled pollination by Maize

plants.• Facilitate commercial hybrid

reproduction.

Significance of male sterility in plant breeding

• Hybrid production requires a female plant in which no viable gametes are borne. Emasculation is done to make a plant devoid of pollen so that it is made female.

• Genetic male sterility is used in hybrid seed production but has limitations due to the need to maintain female parent lines as hetrozygotes & segregation of fertile & sterile plants each generation.

References• Singh, B.D. (1998): Biotechnology, Kaly

ani Publishers, New Delhi.• Snustad, P. and Simmons, M.J. 2003. Pr

inciples of Genetics. (2nd edition). John Wiley , New York.

• http://link.springer.com/article/10.1007%2FBF00029958

• http://www.google.co.in/url?sa=t&rct=j&q=&esrc=s&frm=1&source=web&cd=6&ved=0CFcQFjAF&url=http%3A%2F%2Fkkvinod.webs.com%2Fshare%2Fcms.pdf&ei=h180U4rGIMf5rAfJrYH4BA&usg=AFQjCNFfbLWAYWY0U8hea3hO1kEyhWJjKA&bvm=bv.63808443,d.aGc

• http://www.google.co.in/url?sa=t&rct=j&q=&esrc=s&frm=1&source=web&cd=7&ved=0CGAQFjAG&url=http%3A%2F%2Fwww.sementi.it%2Finformazione%2Fdownload%2Fmateriali%2FESA_13_0834_3.pdf&ei=h180U4rGIMf5rAfJrYH4BA&usg=AFQjCNE95Hh0gWQE3ANvTZGiQoPDT33EMA

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