Plant breeding : incompatibility and male sterility
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May 09, 2024
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Plant breeding : incompatibility and male sterility
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Language: en
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INTRODUCTION TO PLANT BREEDING TECHNIQUE, INCOMPATIBILITY AND MALE STERILITY Submitted by: Hasniya K.M Roll. No: 9 1 st M.Sc. Botany St. Teresa’s College Ernakulam Submitted to, Merin Alice Jacob Assistant professor Dept. of Botany St. Teresa’s College Ernakulam 1
Contents Objectives of plant breeding Important achievements of plant breeding Future prospects Domestication Centre of origin of cultivated plants Incompatibility Male Sterility 2
Plant Breeding is the art and science of changing the traits of plants in order to produce desired characteristics. It is the genetic improvement of plants for human benefit. Technically plant breeding is an exercise in exploiting and manipulating the genetic system for improvement in relation to crop production. This is accomplished by selecting plants found to be economically or aesthetically desirable, first by controlling the mating of selected individuals, and then by selecting certain individuals among the progeny. The goals of plant breeding are to produce crop varieties that boast unique and superior traits for a variety of applications. INTRODUCTION 3
In the mid-1800s Gregor Mendel outlined the principles of heredity using pea plants and thus provided the necessary framework for scientific plant breeding. 4
OBJECTIVES OF PLANT BREEDING 5
Higher yield The ultimate aim of plant to improve the yield of “economic produce on economic part”. It depends on several aspects of plants, such as their response to fertilizers, tillering capacity, resistance to pests, parasites, diseases, adverse environmental conditions, etc. Most breeding programs aim at high crop yields by developing high-yielding and high resistant varieties of plants. It may be grain yield, fodder yield, fiber yield, tuber yield, cane yield or oil yield depending upon the crop species.
This is achieved by developing more efficient genotypes, e.g., hybrid varieties of maize (Z. mays ), sorghum ( S. bicolor ), bajra ( P. americanum ), etc. 6
2. Improved quality The quality of plant produce determines its suitability for various uses. Therefore, quality is an important aspect for plant breeders.
The quality characters vary from one crop to another. Eg . Grain size, color, milling and baking quality in wheat. Cooking quality in rice, malting quality in barley, color and size of fruits, nutritive and keeping quality in vegetables, protein content in pulses, oil content in oilseeds, fiber length, strength and fineness in cotton. 7
3. Resistance against pests and diseases Pests and diseases cause heavy loss of yield in many crop plants. So, imparting resistance to crop plants against pests and pathogens (such as viruses, bacteria, fungi, nematodes, insects, etc.) is the best method to minimize yield loss. Resistant varieties can be developed by incorporating disease-resistant genes with the genetic system of high-yielding plants. Resistant varieties require only cheapest and the most convenient method of pest and disease control. They not only increase production but also stabilize it. 8
4. Resistance against abiotic conditions Crop plants are often exposed to unfavourable or harmful climatic and environmental conditions and stresses, such as drought, frost, heat, high wind, soil salinity etc. These may very severely affect their growth, vigour , vitality, maturation and yield. So, resistant varieties, which can withstand environmental stresses have to be developed. 5. Wider adaptability The plant breeding programme aims at developing the resistance or tolerance property against adverse environmental situation such as drought, flood, cold, high salinity, etc. All these qualities are influenced and altered by genotype-environment interaction. 9
6. Change in maturity duration It permits new crop rotations and often extends the crop area. Development of wheat varieties suitable for late planting has permitted rice wheat rotation. Thus breeding for early maturing crop varieties, or varieties suitable for different dates of planting may be an important objective in many cases. 7. Synchronous maturity This is the simultaneous maturation (flowering and fruiting) of almost all the members of a crop plantation. Synchronous maturity ensures a good harvest of food crops. It is highly desirable in crops like pineapple, citrus, green gram, cowpea, cotton, etc. where usually several pickings are necessary for crop harvest. 10
8. Agronomic characters Modification of agronomic characteristics, such as, plant height, tillering , branching erect or trailing habit etc., is often desirable. For example, dwarfness in cereals is generally associated with lodging resistance and fertilizer responsiveness. 9. Photo-insensitivity Development of photo-insensitive and temperature-insensitive wheat varieties and photo-insensitive rice varieties has enabled their cultivation in new areas. 10. Determinate growth Development of varieties with determinate growth is desirable in crops like mung ( Vigna radiata ), pigeon pea ( Cajanus cajan ), cotton ( Gossypicem sp .), etc. 11
11. Dormancy In some crops, seeds may germinate even before harvesting if there is rain at the time of maturity as in the case of mung, barley ( Hordeum vulgare ), etc. In such cases, a period of dormancy would check the loss due to germination. In certain others, it maybe desirable to remove dormancy. 12. Varieties for new season By scientific breeding methods, new crop varieties can be developed for growing in all seasons throughout the year. Traditionally maize is a kharif crop. But scientists have enabled it to grow as rabi and zaid crops. Likewise, mung can be grown as a summer crop in addition to the main kharif crop. 12
13. Varieties for new areas By breeding practices and experiments, new varieties which are adapted to wider areas and different climatic conditions can be developed. For example, by continued selection and hybridization, many temperate crops can be made adapted to tropical and sub-tropical conditions. 14. Water tolerance and salt tolerance Development of varieties for rain-fed areas and saline soils would help in increasing crop production in India. 13
15. Elimination of toxic substances Certain crops have toxic substances which must be eliminated to make them consumption. For example, khesari ( Lathyrus sativus ) seeds contain the neurotoxin, b-safe for N- oxalylamine alanine (BOAA); that causes paralysis. Similarly Brassica oil contains erucic acid which is harmful to human health. Removal of such toxic substances would increase the nutritional value of these crops. 14
Today crop plants are different from the crop from which they are originated i.e , wild species. This change has been brought about man through plant breeding. The important achievement of plant breeding are : IMPORTANT ACHIEVEMENTS 15
The semidwarf wheat varieties were developed by N.E. Borlaug and his associates at CIMMYT (International Centre for Wheat and Maize Improvement), Mexico. They used a Japanese variety Norin 10 as the source of dwarfing genes. In India major wheat varieties grown today are semi-dwarf varieties. Semi-dwarf varieties were first introduced in 1963 in India. Major examples of these semi-dwarf varieties are Kalyan Sona and Sonalika . 1) Semidwarf wheat and rice varieties 16
These semidwarf wheat varieties are lodging resistant, fertilizer responsive and high yielding. They are generally resistant to rusts and other major diseases of wheat due to the incorporation of resistance genes in their genotypes. These varieties are photoinsensitive and many of them are suitable for late planting. This has enabled cultivation of wheat in nontraditional areas like West Bengal. 17
Semi-dwarf varieties of rice have been developed from an early maturing dwarf Japonica variety of rice called Dee-geo- woo-gen from Taiwan. The first semi-dwarf rice varieties introduced in India in 1966 were Taichung Native 1 (TN-1) and IR-8. Now even these varieties have been replaced by even more superior semi-dwarf rice varieties developed in India itself like Jaya, Ratna , etc. These varies in comparison to wild varieties are lodging resistant, more fertilizer responsive, high yielding and photoinsensitive . Photoinsensitivity has again enabled us to grow rice in non-traditional states like Punjab. 18
Saccharum barberi (Indian sugarcane) had hard stem but poor yield and low sugar content and could only grown in North India, while Saccharum officinarum (noble sugarcane) were having high sugar content but couldn’t be grown in north India primarily due to low winter temperature in this region. C.A. Barber and T.S. Venkataraman at sugarcane breeding institute, Coimbatore took out genes for desired characters like thicker stem and high sugar content from noble cane i.e. Saccharum officinarum and introduced them into Indian cane i.e. Saccharum barberi . This is called Noblisation of Indian cane. Today , the sugarcane breeding in whole world is done by noblisation technique. 2) Nobilisation of Indian canes 19
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Hybrid maize development programme was launched in India in 1957 in collaboration with Rockfeller and Ford Foundations. In some states like Karnataka, hybrid varieties occupy large areas. Popularity was limited in other states because farmers had to replace their seeds every year as these hybrid varieties were double crossed hybrids. So, composite varieties were developed ,e.g., Manjari , Vikram , Sona , Vijay, Kisan etc. Some recently released composites are CO 1., NLD., Renuka , Kanchan , and Diara . The composite varieties often yield as much as the hybrid varieties and do not have the drawbacks of the latter. More notably, the farmers need not replace the seed every year in the case of composite varieties. 3) Hybrid millets 21
CO 1 22
Cotton accounts for 85% of raw material for textile industries in India. ICAR in 1967 Launched All India Co-ordinated Cotton Improvement Project, establishing headquarters at Coimbatore (Tamil Nadu). Laxmi , jayadhar , suvin ,MCU5 , Bikaneri nerma Savitri , Jayalaxmi etc. are some important cotton varieties. First hybrid cotton variety was H4 which was developed in 1970 by Gujarat Agriculture University from two G.hirsutum strains. G- cot. Dh-7 and G- cot. Dh-9 are recently released varieties. Recently, cytoplasmic male sterility (CMS) is being used to produce hybrid cotton varieties. 4) Hybrid cottons 23
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Genetic manipulation of population by increasing the frequency of desirable alleles in cross pollinated crops and introducing male sterile in self pollinated crops like wheat and Rice.
Intensive breeding of pulses and oil seed crops as it was done in cereals and other crops.
Proper breeding methods with improved crop management practices.
Use of heritability methods with improved crop management practices.
Development of improved high yielding varieties of vegetable and seed crops. Quality Improvement in Oil seed and Vegetables.
Use of transgenic plants as a medicine. E.g. Potato.
Development of varieties which are desirable for mechanical threshing and cultivation. FUTURE PROSPECTS OF PLANT BREEDING 25
Crop domestication is the process of artificially selecting plants to increase their suitability to human requirements: taste, yield, storage, and cultivation practices. Domestication is the first step of making the wild weed species to cultivated plants. Most of the characteristics of wild species have been affected under domestication which involves three processes like mutation, hybridization and genetic recombination under the influence of human selection or natural selection. Some characters have got changed, some have lost and many have developed during domestication. DOMESTICATION 26
Some of the important characters which have been affected are listed below: Elimination or reduction of shattering of pods or spikes. Elimination of dormancy period. Decrease in toxins or other undesirable substances. Increase in size of the grains or fruits.
Plant type change like decrease or increase in height, more number of tillers, leaf size, branching pattern, etc.
Early maturity. Increase in economic yields. 27
8. Change in photoperiodic behaviour . 9. Mode of reproduction. 10. Pollination habit. 11. Synchrony in flowering.
12. Loss of defensive adaptation like hairs, thorns, etc.
13. Selection of bisexual variety rather than dioecious . 14. Decrease in variability. Selection of polyploidy. 28
The centre of origin is a geographical area where the particular group of organisms (either domesticated or wild) first originated on earth. Nikolai Ivanovich Vavilov has proposed that crop plants evolved from wild species in the areas showing diversity and termed them as primary centers of origin. From these places the crops moved to other areas with the movements of man. But in some areas, certain crop species show considerable diversity of forms although they did not originate there. Such areas are known as secondary centres of origin of these species. Vavilov has suggested eight main centres of origin. CENTRES OF ORIGIN OF CULTIVATED PLANTS 29
Chinese centre It is considered to be one of the earliest and largest independent centres of origin of cultivated plants. This centre includes mountain regions of central and western China. The endemic species listed from this centre include Soya bean, radish, Turnip, Pear, Peach, Plum, Colacasia , Buckwheat, Opium poppy, brinjal , apricots, oranges, china tea etc. Pear Peach Plum 30
2. Himalayan centre It also known as the Indian centre of origin. This centre includes regions of Assam, Burma, Indo-china and Malayan Archipelago. The endemic species listed from this centre include Rice, red gram, chick pea, cow pea, Mung dal, brinjal , cucumber, sugar cane, black pepper, cotton, Turmeric, indigo, millets etc. It has two subcentres , Indo-Burma: Main Centre (India): Includes Assam, Bangladesh and Burma, but not Northwest India, Punjab,nor Northwest Frontier Provinces. Siam-Malaya-Java: Indo-Malayan Centre: Includes Indo-China and the Malay Archipelago. Chick pea 31
3. Mediterranean centre This centre includes borders of Mediterranean Sea. Most of the cultivated vegetables have their origin in this region. The endemic species listed from this centre include Durum wheat, emmer wheat oat, barley, Lentil, pea, grass pea, broad bean, cabbage, asparagus, pepper mint etc. Durum wheat Barley Asparagus 32
4. Abyssinian centre This region includes Ethiopia and parts of Somalia. The endemic species listed from this centre include Wheat, sorghum, bajra , safflower, castor, broad bean, okra, coffee etc. Safflower Okra Bajra 33
5. Central Asian centre This centre includes north-west India, Afghanistan, Uzbekistan and western China. The endemic species listed from this centre include Bread wheat, club wheat, sesame, linseed, muskmelon, carrot, onion, garlic, apricot, grape, hemp, cotton etc. Club wheat Hemp Muskmelon 34
6. Asia minor centre Also called Middle east centre . This centre covers near East Asian regions like Iran and Turkmenistan. The endemic species listed from this centre include Wheat, rye, Pomegranate, Almond, Fig, Cherry, Walnut, etc. 35
7. Central American centre This centre includes southern parts of Mexico, Costa Rica, Guatemala and Honduras region. The endemic species listed from this centre include Maize, rajma, lima bean, melon, pumpkin, sweet potato, arrowroot, Chilly, cotton, papaya, guava, avocado etc . Sweet potato Lima bean Arrowroot 36
8. South American centre This centre includes Peruvian regions, islands of southern Chile, Brazil and Paraguay regions. The endemic species listed from this centre include Potato, sweet potato, lima bean, tomato, papaya, tobacco, quinine, cassava, rubber, Ground net, Cocoa, pineapple etc.
It has three subcentres Peruvian, Ecuadorean, Bolivian Centre Chiloe Centre (Island near the coast of southern Chile) Brazilian-Paraguayan Centre. Cocoa 37
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INCOMPATIBILITY Incompatibility in the failure of plants with normal pollen and ovules to set seed due to some physiological hindrance which prevents fertilization. A common cause of incompatibility is the failure of the pollen tubes to grow down the styles so that fertilization may occur. 39
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1. Heteromorphic system When the species has two or three different kinds of arrangement of floral parts, each type is self incompatible but compatible with others. Here the genes or alleles associated with incompatibility are also linked with length of style and filament. Two types: Distyly Tristyly 41
Distyly In Primula , there are two types of flowers:,
Pin type-long style, short filament, large stigmatic cell, small pollen.
Thrum type-short style, long filament, small stigmatic cell, large pollen In the case of Distyly , the only compatible mating is possible between Pin and Thrum flowers.
The characteristic is governed by single S-gene (self-incompatibility gene); Ss produce Thrum flowers and ss produce Pin flowers. 42
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2. Tristyly In Lythrum , three types of flowers with different stylar length exist Here the stylar length is governed by two independent loci M and S. Plants with S have short style irrespective of the nature of other allele. The three different morphological types are self incompatible but cross compatible. 44
2. Homomorphic system In this case there is no morphological distinction between the self incompatible flowers and the incompatibility is governed by multiple alleles. It is due to the physiological change. Gametophytic self-incompatibility : When the self incompatibility is controlled by the genetic constitution of gametes, it is known as gametophytic self incompatibility system. Sporophytic self-incompatibility: When the self incompatibility is governed by the genotype of pollen producing plant (Sporophyte), it is called sporophytic system. 45
MALE STERILITY Male sterility is characterised by the deficiency in pollen formation or the nonfunctional pollen production. i.e., there may be some deficiency in the process of microsporogenesis . But in some cases the viable pollen are formed but anthers fail to dehisce. The process of male sterility is totally under genic control which may be nuclear gene or cytoplasmic-gene. Depending on this factor male sterility can be grouped as follows: (a) Genetic male sterility (b) Cytoplasmic male sterility (c) Cytoplasmic-genetic male sterility. 46
Genetic male sterility: The pollen sterility, which is caused by nuclear genes, is termed as genic or genetic male sterility. The male sterility is governed by a single recessive nuclear gene, ms and there is no influence of cytoplasm. Cytoplasmic Male Sterility: The pollen sterility which is controlled by cytoplasmic genes is known as cytoplasmic male sterility (CMS).This type of male sterility occurs due to the mutation of mitochondrial gene or some other cytoplasmic factors outside the nuclear genome which make the plant male sterile. Cytoplasmic Genetic Male Sterility: When pollen sterility is controlled by both cytoplasmic and nuclear genes is known as cytoplasmic genetic male sterility. 47
REFERENCE Allard, R. (1999). Principles of Plant Breeding. New York: John Wiley and S. Chopra, V.L. (1968). Plant breeding: Theory and practice. New Delhi. Oxford and IBH publishing company. Frey, K.J. (1977). Plant breeding. The IOWA State University press. Kr.Kumar , D. (2006). Plant Breeding Biometry Biotechnology. London: New central book agency (P) Ltd. https://agriinfo.in/male-sterility-1752 48