Authors: DEEPAK SAPKAL ,VAISHALI SAPKAL, ADITI SHARMA, JITENDRA WAYDE and AKSHAY DANGE
Male sterility is defined as an absence or non-function of pollen grain in plant or incapability of plants to produce or release functional pollen grains; such phenomenon was reported first time by Kolreuter in 1763. It occurs in the nature sporadically, perhaps due to mutation or due to environmental effect. Why is the male sterility observed in male part only? How to express male sterility and its classification.
Male sterility is more prevalent to female sterility :
a) Male sporophyte and gametophyte are less protected from environment than ovule and embryo sac.
b) Male sterility can be easily detected SINCE a large number of pollen is available FOR RESEARCH, it Is easy to assay male sterility with the help of some staining technique (caramine, lactophenol or iodine).
c) Male sterility has self propagation potential in nature (can still set seed) and is important for crop breeding, such types of function does not occur in case of female sterility.
Reason for the expression of male sterility :
a) Absence or malformation of a male organ (stamens) in bisexual plants or no male flowers (dioecious plants).
b) Failure to develop a normal microsporogenous tissue in anther.
c) Abnormal microsporogenes produce deformed or inviable pollen.
d) Abnormal pollen maturation (inability to germinate on compatible stigmata).
e) Sometimes the anther does not dehiscent, even if the pollens are viable. This is due to the sporophytic control.
On the basis of origin of the abnormality:
a) True male sterility: This is due to an unisexual flowers that lack male sex organs {dioecy (staminate and pistillate flowers are occur on different plant e.g., papaya, date, hemp, asparagus, and spinach) and monocey (Staminate and pistillate flowers are occur in the same plant, either in the same inflorescene, e.g., Castor, mango and coconut, or in a separate inflorescences like as maize, chestnut, strawberries, rubber, grapes and cassava)}.The bisexual flowers with abnormal or non-functional microspores (leading to pollen abortion).
b) Functional male sterility: The anthers are failed to release their contents even though the pollen is fertile.
c) Induced male sterility : Plant breeder may use physical (X, beta and gama rays etc) or chemicals (Ethyle methyl sulphonate, Methyl methane sulphonate etc) agents are to be used for induced male sterility.
True male sterility is of three types a) Nuclear b) Cytoplasmic c) Cytoplasmic - genetic.
a) Genetic male sterility (nuclear-genic) such type of male sterility widespread and it will be used in seed propagated plants. Now a days this is an out dated technique because major drawback is for production of hybrid seed. In this techniques plant breeder has to be rough out fifty per cent fertile plants.
Genetic male sterility is of three types:
1. Environmental in sensitive:
2. Environmental sensitive:
• Thermo genetic male sterility:
• Photo period genetic male sterility:
3. Transgenic male sterility
b) Cytoplasmic male sterility: Such type of male sterility governed by mitochondrial gene. Its transfer through the egg cell only (maternal factor). CMS has been found in species including corn, sorghum, sugar beet, carrot and flax. This system has a real advantage in an ornamental vegetative species and also in fodder crops, where seed is not economic parts. Because all the offspring are a male sterile, hence allowing them to remain fruitless. By non fruiting, the plant remain fresh and in bloom for a long period of time.
c) Cytoplasmic-genetic male sterility: Such type of a male sterility governed by both cytoplasm and nuclear gene interaction. It can be used in vegetative and seed propagated plants. Now a day’s CGMS technology is being mostly used for the production of a hybrid seeds.
About Author / Additional Info:
Dr. DEEPAK SAPKAL and ADITI SHARMA, Assistant Professor (Genetis and Plant Breeding), Lovely Professional University, Jalandhar, State : Punjab (INDIA).
VAISHALI SAPKAL , JITENDRA WAYDE and AKSHAY DANGE. are M.Sc. Student (Genetics and Plant Breeding)