Quality breeding for crop improvement

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By: chhabra61 (49 month(s) ago)

Very informative for breeding students. Pl. send me a copy for teaching purpose at chhabra61@gmail.com Thanks Prof AK CHHABRA CCSHAU HISAR

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COURSE SEMINAR ON “BREEDING FOR QUALITY IN CROP PLANTS” Speaker R.L. Bhakre Seminar Incharge Dr. R. S. Nandanwar Head, Department of Agricultural Botany, Post Graduate Institute, Dr. PDKV, Akola. Major Advisor Dr.R.B.Ghorade Senior Research Scientist, Sorghum Research Unit, Dr.PDKV, Akola 1

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2 Quality refers to the suitability or fitness of an economic plant product in relation to its end use. Definition of quality varies according to our needs from the viewpoint of seeds, crop growth, crop product, post-harvest technology, consumer preferences, cooking quality, keeping quality, transportability etc. (Gupta,2001). What is Quality?

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3 QUALITY TRAITS A trait that defines some aspect of produce quality is called quality trait. Each crop has a specific & often somewhat to completely different set of quality traits.

Classification of Quality traits : 

Classification of Quality traits Morphological Organoleptic Nutritional Biological others 4

Morphological Traits : 

Morphological Traits 5 related to produce appearance mainly concerned with size & colour of the produce, eg.,grain/fruit size, grain/fruit colour etc. Easily observable. Usually play the main role in determining consumer acceptance of the produce.

Organolaptic traits : 

Organolaptic traits 6 Concerned with palatability of the produce . eg., taste,aroma, smale, juiciness, softness,etc. Easily detected Very important in influencing consumer preferences

Nutritional Quality : 

Nutritional Quality 7 Determine the value of the produce in human/ animal nutrition. Includes protein content & quality, oil content & quality, vitamin content, mineral content, etc., and also the presence of antinutritional factors. Not easily appreciated by consumers & farmers, but they are of paramount value in detremining human & animal health.

Biological quality traits : 

Biological quality traits 8 The traits included in this group define the actual usefulness of the produce when consumed by experimental animals; There usefulness to humans is usually predicted on this basis. eg.,Protein efficiency ratio,biological value, body weight gain,etc. These traits are not obvious to consumers & growers but are extremely valuabe in detrmining the utility of produce for human &/or animal consumption

Other quality traits : 

Other quality traits 9 Includes all other quality traits that are not included in the above categories. eg., cooking quality of rice, keeping quality of fruits & vegetables, fibre strengh of cotton etc. Many of the traits in this group are of prime importance in determining the usfulness of the concerned produce.

QUALITY TRAITS OF SELECTED CROPS : 

QUALITY TRAITS OF SELECTED CROPS 10

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11 Wheat white or amber grain colour, medium to bold size, hard vitreous texture, & lustrous appearance are important features for good market quality. High lysine content & good baking quality are essential for use in biscuit & bread manufacturing. Rice White coloured fine & long slender grains, taste & fragrance, less breakage in milling, more hulling recovery, better cooking quality, high protein & lysine contents. Maize bold flint grains with attractive colour, high lysine, oil & sugar contents The seed colour should be yellow or white. Sorghum Bold, thin pericarp, white grains of attractive shape & size, high protein & lysine content

Pearl milletBold lustrous & pearly amber colour grains with high iron contents BarleyIn malting barley, low protein content & high extract of soluble oligosaccharides after malting are desirable characters. Low protein produces less haze in beer & high oligosaccharides are suitable for fermentation. : 

Pearl milletBold lustrous & pearly amber colour grains with high iron contents BarleyIn malting barley, low protein content & high extract of soluble oligosaccharides after malting are desirable characters. Low protein produces less haze in beer & high oligosaccharides are suitable for fermentation. 12 Pulses Attractive shape, size & colour of grains, high protein contents; high methionine & tryptophan; & less flatulence. Oil seeds Attractive shape, size & colour of seeds, high oil content free from antinutritional factors & more proportion of unsaturated fatty acids.

SugarcaneModerate hardness, long internode, optimum (low) fibre for milling; sucrose ratio, high sucrose content & good quality of juice. : 

SugarcaneModerate hardness, long internode, optimum (low) fibre for milling; sucrose ratio, high sucrose content & good quality of juice. 13 Cotton Fibre length, strength, fineness, maturity, uniformity & colour Tobacco Short & thin leaves with less branched veins are preferred for cigar. Thin leaves are also preferred for pipe smoking. Thick leaves are suitable for cigarettes. High nicotin content for bidi, hookah & chewing & low for cigarettes are preferred. High sugar content is also preferred.

PotatoAttractive shape, size & colour of tubers, taste, cooking quality, thin skin, keeping quality & high starch content.VegetablesHigh vitamin & mineral contents, good taste, keeping quality & cooking quality .Forage cropsGreater nutritive value, more palatability & freedom from toxic substances. : 

PotatoAttractive shape, size & colour of tubers, taste, cooking quality, thin skin, keeping quality & high starch content.VegetablesHigh vitamin & mineral contents, good taste, keeping quality & cooking quality .Forage cropsGreater nutritive value, more palatability & freedom from toxic substances. 14 Medicinal plants High content of active substance. Jute, kenef & sunnhemp length, strength, fineness, colour, luster & freedom from knots & specks.

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15 Four major goals for breeding for improved nutritional quality. These are breeding for high content & quality of protein, (2) high content & quality of oil, (3) high vitamin contents, & (4) low toxic substances which are harmful for human health.

NUTRITION & NUTRIENTS : 

NUTRITION & NUTRIENTS 16 The scientific study of food in relation to health is referred to as nutrition. Various chemical components of food which provide nourishment to the body are called nutrients. These are carbohydrates, fats, proteins, vitamins, minerals & water. Good nutrition refers to adequate intake of well balanced diet, which supplies all essential nutrients required by the body. Malnutrition may result from deficiency, excess or imbalance of nutrients. Hence all the nutrients should be taken in adequate quality.

Protein content & Quality : 

Protein content & Quality 17 Proteins are an essential component of the diet. Protein are organic macromolecules consisting of a long chain of amino acids linked with each other by peptide bonds formed by carboxyl(-COOH) group of one amino acid with amino group(-NH2) of other amino acid The nutritional properties of proteins are determined by their amino acid composition There are 21 amino acids which are important in human nutrition. These can be classified into two groups, viz. (1) essential amino acids & (2) non essential amino acids.

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18 EAA can’t be synthesized in human body & their requirement has to be met through dietary intake. There are ten EAA (methionine, isoleucine, leucine, lysine, threonine,tryptophan, valine, phenylalanine, histidine, & arginine). Out of these arginine & histidine are considered non essential for the adult. The non EAA can be synthesized in human body & they need not be supplied through diet. These are cystine, cysteine, proline, glycine, serine, alanine, aspartic acid, hydoxyproline, glutamic acid, norleucine & tyrosine. The quality of protein is determined by the content of essential amino acids. The sulphure containing amino acids (Tryptophan, Threonine, Isolecine, Lysine, Valine & Methionine) are referred to as limiting amino acids.

Table 1: EAA deficient in some vegetarian foods: : 

Table 1: EAA deficient in some vegetarian foods: 19 Singh,2002

Vitamins : 

Vitamins 20 A vital substance which is required in very small quantity & is essential for proper growth & good health is called vitamin. Vitamins are essential for body growth, maintenance & reproduction. Based on their solubility, vitamins are of two types. Viz. (1) fat soluble (A, D, E & K) & (2) water soluble: (B group vitamins & vitamin C). Vitamin D & folic acid can be partly synthesized in the body. Rest of the vitamins has to be supplied through diet. Vitamin D is found in fats other vitamins are found in fleshy fruits & green vegetables.

NUTRITIONAL QUALITY OF CEREALS & PULSES : 

NUTRITIONAL QUALITY OF CEREALS & PULSES 21 Cereals are important sources of carbohydrates. The contribution of cereals is 70% to the total calories in human diet. They contribute 50% to the global protein requirement, while grain legumes contribute only 20 %. Remaining 30% comes from animal products. The average protein content in the cereals ranges from 10 to 13%. However, the cereal protein is deficient in lysine, tryptophan & threonine.

Cereal Protein Quality : 

Cereal Protein Quality 22 Cereal proteins are classified in to four groups based on their solubility: 1)albumins 2)globulins 3)prolamines & 4)glutelins Major protein fraction of cereal proteins Singh,2002

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23 In all cereals, Prolamines are relatively rich in proline & glutamine but low in basic amino acids including lysine. Therefore, they have poor nutritional value. Generally, prolamin content in cereals is negatively associated with total protein content. Cereals contain about 70% prolamine & glutelin and 30% albumin & globulin. Several mutants with improved protein quality have been identified in cereals like maize, jowar & barley (Table 2).

Table 2:The list of mutants affecting protein quality in cereals. : 

Table 2:The list of mutants affecting protein quality in cereals. 24 Source: Pirman et al.,1997

Legume Protein Improvement : 

Legume Protein Improvement 25 Legumes contain protein from 18 to 28% which is almost double of cereals (exception,soybean:43%). In pulses, two types of proteins, viz. albumin & globulin are found. The major storage protein in grain legumes is globulin which constitutes about 80% of the total seed protein. In chickpea, globulin is of three types, viz. alpha, beta & gamma. The alpha globulin accounts for more than 80% of the total protein. In faba & pea, globulin is of two types, viz. legumin & vicilin. Legumin is less soluble in salt solution than vicilin. Moreover, legumin does not coagulate at high temperature (950C) while vicilin coagulates.

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26 Proteins legumes are deficient in methionine & tryptophan. Moreover, they contain several toxic substances such as protease inhibitors, haemagglutinins, lathyrogens, glucocides, goitrogens, cyanogens, metal binding factors & antivitamin factors. However, many of these toxic compounds are destroyed during cooking. Some of these toxins have to be eliminated through breeding. The mixture of cereals & pulses in 3 : 1 ratio provides nutritionally balanced diet.

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27 Table 3 :Protein fractions present in legume seeds. Pirman et al.,1997

GENETICS OF NUTRITIONAL TRAITSThe quality traits may be governed by (1) Oligogenic Inheritance, (2) Polygenic Inheritance, & (3) Maternal Effects : 

GENETICS OF NUTRITIONAL TRAITSThe quality traits may be governed by (1) Oligogenic Inheritance, (2) Polygenic Inheritance, & (3) Maternal Effects 28

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29 Oligogenic inheritance Inheritance is governed by one or few major genes Each gene has large & easily detectable effect on the expression of nutritional quality character. The differences between characters of high & low value is clear cut. In Sorghum, high lysine content is controlled by single gene with incomplete dominanace. In barley, high lysine content is governed by one major gene plus several minor genes. In safflower, fatty acid composition is governed by one major gene with three major alleles. In tomato, high beta carotene content is conditioned by two major genes plus modifires.

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30 Polygenic inheritance Inheritance is governed by several genes each with small additive effect In such inheritance, the variation for a character is continuous from one extreme to another. Classification of plants into clear cut classes is not possible. The protein content in cereals & pulses & seed oil content in oilseed crops are governed by polygenes. Characters which are governed by polygenes are sensitive to environmental changes & generally have low heritability. In carrot, high carotenoid content exhibits complex inheritance pattern.

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31 Maternal Effects: Important/present in case of some quality traits. Usually, such traits are concerned with grain characteristics, eg.,seed size(quite common),protein content,etc. For ex., reported for protein content in chickpea, fatty acid composition in maize, soybean & rapeseed is influenced by genotype of maternal parent. Maternal effects have same effect on genetic advance under selection as other environmental factors, i.e., they confuse correspondence between genotype & phenotype &, thereby, reduce the progress under selection. Therefore, selection schemes must make allowances for maternal effects if & where present.

Table 4: Genetics of nutritional quality characters in some crop plants : 

Table 4: Genetics of nutritional quality characters in some crop plants 32 Gupta,1992

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33 SOURCES OF QUALITY TRAITS: (1) a cultivated variety, (2) a germplasm line, (3) a spontaneous or induced mutant, (4) a somaclonal variant, (5) a wild relative and (6) a transgene

1) A cultivated Variety : 

1) A cultivated Variety 34 most preferred source eg. Atlas 66 & Naphal have been used as sources of high protein content in USA. 2) A Germplasm Line eg. High lysine (3% of total protein) lines of sorghum, viz., IS 11167 & IS 11758, were identified from Ethiopian collections. These lines also have (15%) protein but their seeds are shrivelled & red in colour. They have been extensively used in breeding programmes.

3) A mutant : 

3) A mutant 35 many quality traits have been contributed by spontaneous/induced mutants (Table 2). There are also examples of isolation of desirable mutants from mutant lines for quality traits. eg. P-721 opaque mutant of sorghum has opaque endosperm, which is not liked by consumers. A vitreous endosperm DES-induced mutant was isolated from P-271 opaque line; this mutant has high lysine content.

4) A Somaclonal Variant : 

4) A Somaclonal Variant 36 Somaclonal variants may sometimes show an improvement in a quality trait. eg., a somaclonal variant of sweet potato had deeper & more stable root colour, which is preferred by consumers; this variant was released as a new variety called ‘ Scarlet’ 5) A wild Relative There are several instances where genes for improved quality were contributed by a wild relative (Table 5) In many cases, the quality trait is not expressed as such in the wild species, but it is detected only in the segregants recovered from its cross with the cultivated relative; such traits are called latent traits. eg., L.hirsutum, a wild relative of tomato, produces small green fruits. Yet some of the lines extracted from a cross between tomato & L. hirsutum showed enhanced red colour, while some others showed considerably higher carotene content.

Table 5: Wild relatives from which quality traits have been/can be transferred.(Chopra ,1989) : 

Table 5: Wild relatives from which quality traits have been/can be transferred.(Chopra ,1989) 37

6) A Transgene : 

6) A Transgene 38 A gene from any organism, including the species into which it is transferred, that is introduced into the genome of an organism using the techniques of genetic engineering is called transgene. Transgenes provide a powerful means for modification of quality traits. In order to use transgenes effectively & successfully, biosynthetic pathway, or at least key enzymes involved in biosynthesis, leading to production of concerned trait should be known. eg., ‘Laurical’ ( B. napus variety having high lauric acid) & B. napus variety producing ‘hirudin’(antithrombin protein of high pharmaceutical value) Production of hirudin & similar other novel proteins/ biochemicals in plants may be regarded as a novel quality trait, which drastically changes the end use pattern of crop produce.

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39 BREEDING APPROACHES: 1)Evolution of germplasm. 2)Mutagenesis. 3)Hybridization. 4)Interspecific hybridization. 5)Somaclonal variation. 6)Genetic engineering

1) Screening of Germplasm : 

1) Screening of Germplasm 40 important for such traits that are not obvious, viz.,traits related to chemical composition. eg.,The lysine germplasm lines of sorghum Further breeding effort will be required to combine the quality trait with good agronomic features &/or yield since the germplasm line is expected to be inferior in yield & agronomic characteristics. 2) mutagenesis A desired quality trait may be present in spontaneous/induced mutant (Table 2).

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41 Varieties release for quality through mutation breeding

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Contd………. Source:Vijaykumar ,2002 42

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43 Contd……

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44 Source:Vijaykumar ,2002 Contd……

3) Hybridization : 

3) Hybridization 45 Most widely used breeding approach to develop high yielding varieties with desirable quality traits. The breeding methods used to handle segregating generations derived from appropriate crosses depend mainly on the type of parents involved in the cross. If both parents of a cross are high yielding varieties having good agronomic features, pedigree method will be the most suitable . If one of the parents has inferior agronomic features, backcross scheme will be the most appropriate; only a limited number (2-3) of backcross may be made, if the inferior parent has some desirable features as well (in addition to the quality trait). The segregating generation may be subjected to sib-mating, in place of selfing, & selection in an effort to break undesirable linkages with the gene controlling quality traits. These considerations apply when quality trait is governed by oligogenes (Table 6 ).

Table 6 :Selected examples of breeding for improved protein/lysine content : 

Table 6 :Selected examples of breeding for improved protein/lysine content 46 Singh, 2002 Quality traits governed by polygenes may be improved by subjecting the segregating generations to a form of recurrent selection Recurrent selection for two cycles increased seed protein content of rajna (french bean) from 21.9% to 24.6%. In case of soybean, there was an increase of 3.3% (from 42.8 to 46.1 per cent) in seed protein content in response to 5 cycles of recurrent selection.

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47 4) Interspecific Hybridization When individual from two distinct species of the same genus are crossed. Wild relative often contribute useful quality genes, eg.,fruit colour, fruit size, pro- vitamin A & vitamin C content in tomato etc.(Table 5) In any case, the high quality lines derived from such crosses will usually serve as parents in hybridization programmes; it is unlikely that they will be used directly as varieties. 5) Somaclonal Variation Genetic variation present in tissue culture-raised plants (somaclonal variation) has been exploited for crop improvement & several somaclonal variants are being used as commercial varieties. eg., ‘Scarlet’ variety of sweet potato has improved & more stable root colour.

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48 BREEDING METHODS Breeding methods used for improvement of quality do not differ from breeding methods used for any other character. Breeding methods that are extensively used for improvement of quality traits include backcross, pedigree method, single seed descent, recurrent selection, progeny selection & mutation breeding. In common bean (Phaseolus vulgaris), pedigree, single seed descent & recurrent selection methods have been used for improvement of protein content. Two cycles of recurrent selection increased seed protein from 21.9% to 24.6%. In soybean, five cycles of recurrent selection increased seed protein from 42.8 to 46.1 per cent. In Sorghum, pedigree breeding procedure was used for developing high lysine lines.

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49 In barley, backcross method was used for development of high lysine lines. In barley, high lysine line had small seed size & low grain yield. In sunflower, seed oil content was increased from 30% to almost 50% by Russian breeders in 50 years using modified recurrent selection. In safflower, oil content was increased from 37% to 50% through reduction in hull content. In maize, seed oil content increased from 4.7 to 17% & protein from 10.9 to 23.5 after 70 cycles of recurrent selection in USA. But there was a drastic reduction in grain yield. Mutation breeding has been used for development of high lysine lines in Sorghum, barley & maize. Diethylsulphonate (DES) has been used in Sorghum & EMS & EI in barley for induction of high lysine mutants.

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50 SCREENING TECHNIQUES Breeding for enhanced nutritional quality involves lot of chemical analysis. The breeding material has to be screened for protein content, amino acid composition, seed oil content, fatty acid composition, vitamin contents & antinutritional factors. This requires close cooperation of biochemist. The selection of plants with better nutritional quality is done based on chemical analysis should be simple, cheap & rapid. Now rapid chemical analysis methods are available for protein estimation, seed oil estimation, fatty acids & amino acid analysis.

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51 Seed Oil Analysis The seed oil analysis is done with the help of Nuclear Magnetic Resonance (NMR) or Nuclear Infrared Analyser (NIR). This is the non destructive method of oil analysis. After oil analysis the seeds can be used for sowing purpose. Several single plants in segregating populations can be analyzed. This method is quite simple, highly accurate & very fast. By this method, 300- 400 samples can be easily analyzed per day.

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52 Protein Analysis Now analysis of grain protein is done with the help of protein analyser. The analysis is based on the principle of infra-red reflectance measurement. The seed is grouped into flour which is used for the analysis. This method is very fast. By this method 200-300 samples can be easily analysed per day. Individual amino acids can be estimated by colorimetric method or microbiological method. Analysis of antinutritional factors is carried out by chemical method. The old methods of protein estimation (Kjeldahl method) & oil analysis (Soxhlet method) were very much time consuming though more accurate. Now fast methods have been developed.

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53 BREEDING FOR LOW TOXIC SUBSTANCES In some grain legumes, oilseeds. Vegetables, fruits & forage crops toxic substances are found. These toxic substances have adverse effects on human & animal health. Feeding of forage with toxic substance will adversely effect the health of animal. Therefore, it is essential to develop varieties of forage & food crops with low level of toxic substance so that it should not have adverse effect when consumed by animals. Considerable progress has been made in the development of varieties with low toxin content in above crops. Breeding for reduction in toxic substances requires lot of chemical analysis. Hence development of simple, cheap, rapid & reliable methods of chemical analysis is essential.

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54 Antinutritional factors in legumes

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55 Contd…….. Source:Manickam,2002

TABLE 7 . Toxic substances found in different food & fodder crops : 

TABLE 7 . Toxic substances found in different food & fodder crops 56 Singh,2002

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57 PRACTICAL ACHIEVEMENTS Varieties with improved nutritional quality have been developed in several food crops in many countries. In common bean, seed protein has been increased from 21.9 to 24.6, & in soybean seed from 42.8 to 46.1%. In sunflower, seed oil content has been increased from 32% to almost 50% in USSR, & in safflower from 37 to 50%. In maize, seed oil content has been increased from 4.7 to 17% & protein content from 10.9 to 23.5%. In wheat, Atlas-66 is an important source of high protein which is being used in breeding programmes for improvement of protein content.

Varieties with improved quality released in some crop plants in India : 

Varieties with improved quality released in some crop plants in India 58 Singh,2002

Limitations : 

Limitations 59 Most are polygenic Difficult to estimate & evaluate, hence more finance required Low heritability & affected by environment There is negative association of seed protein with grain yield in both cereals & pulses. In some cases, improvement in quality leads to reduction in grain size and yield. For example, in barley selection for high lysine content causes reduction in grain size and grain yield. Sometimes, the quality character is found in wild relatives or species The analysis requires close cooperation of biochemist which sometimes becomes limiting factor in the progress. Biotechnological tools have not been used widely in all crops.

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16-60 THANK YOU

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