Importance of Male Sterility and self incompatibility in crop improvement
By Idu Paul Odey
1. Male Sterility (MS) and Self-Incompatibility
1. Male Sterility (MS)
2. Self-Incompatibility (SI)
2. Types of Male Sterility and Self-Incompatibility Systems 1. Types of Male Sterility
2. Types of Self-Incompatibility
3. How MS and SI affect Reproduction in plant and correction of problems 1. Effect of MS in Reproduction
2. Effect of SI in Reproduction
4. MS and SI Effect/Use in Crop Breeding Exercise
1. Male Sterility in Plant Breeding
2. Self-Incompatibility in Crop Breeding
Self-incompatibility (SI) and Male Sterility (MS) are widespread phenomena in flowering plants. It has however been suggested that in classifying plants according to why they may fail to set seed, that, it is desirable to distinguish between incompatibility and sterility. With Self-incompatibility there is restriction of breeding within populations and it seems to contribute through the establishment of unilateral barriers between self-incompatibility and self compatible populations. Male sterility on the other hand is characterized by non-functional gametes; caused by chromosomal aberration, genes action, etc
Two phenomena plays important roles in plant breeding; as plant breeders are often interested in modifying the breeding system in crop plants in order to substitute ether permanently or temporarily some mating system that serves their purpose better than the natural system of the species
In respect to this the purpose of this term paper is to review the importance of Male sterility and Self0incompatibility in crop improvement. This term paper shall however consider the various types of MS and SI; how they affect reproduction in plants; how the problem can be corrected and finally how the corrections affect a crop improvement or plant breeding exercise
1. Male Sterility (MS) and Self-Incompatibility (SI)
1.1.1Male Sterility (MS)
Lasa and Bosemark (1993) saw Male Sterility in plant as an inability to produce or to release functional pollen and is the result of failure of formation or development of functional stamen, microspores or gametes. Another author, Burojevic (1990) stated that male sterility is a phenomenon when plans do not produce viable pollen grains, which is due either to the stunting of male sexual organs (stamens) or to mitotic irregularities in apparently normal stamens leading to the development of abnormal microspores and nonfunctional or sterile pollen grains.
The definition so considered, stressed on the ability of the male gametes or organs to render functional gametes or pollen. This may be generally controlled as ascertained by Borojevic (1990) or as a result of the effects of mutant genes or cytoplasmic factors of the combined efforts of these two factors.
1.1.2 Self-Incompatibility (SI)
Among hermaphroditic plant species there are several genetically controlled system for enforcing cross-pollination that operates through the incompatibility of pollen and style.
Incompatibility is the inability or failure of the pollen to germinate on the stigma or the situation where there is a slow pollen tube growth down the style. In the case of incompatibility the pollen and ovules are functional, and unfruitfulness results from some physiological hindrance to fertilization. However, it is believed that, the incompatibility reaction appears to be biochemical process under rather simple genetic control. Borojevic (1990) mentioned some of the several causes of incompatibility to be i) Protandry – a condition in which stamens mature before the stigma in the same flower preventing pollen grains from pollinating the stigma...