Maximizing productivity of wheat and barley under dry-land systems HYBRIDIZATION. Faddel Ismail NCARE June,

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1 Maximizing productivity of wheat and barley under dry-land systems HYBRIDIZATION Faddel Ismail NCARE June,

2 Hybridization Hybridization is the process of crossing two genetically different individuals to create new genotypes (organism). Parent 1 with BB and parent 2 with bb, produces progeny with Bb, which is a hybrid (F1 generation).

3 Cross identical parents X X

4 Cross different parents X X

5 Hybridization It is a common way of generating genetic variability. Hybridization of plants occurs in nature through various mechanisms. insect-pollination (oil palm), wind-pollination (corn). Such plants are referred to as cross-pollinated plants. Natural hybridization is the norm in cross-pollinated plants.

6 Hybridization Hybridization: mixing (fusion) male genetic material with female genetic material. - Production of gametes - Transfer of male gametes - Mixing (merging) genetic material - Forming zygote (new organism) These occur in the reproduction organ The flower

7 Flower structure

8 Non-reproductive organs Petals flower organs that are often brightly colored to attract pollinators Corolla group of petals Sepals leaf-like organs outside the corolla; help protect the unopened flower bud. Calyx group of sepals in a flower

9 female organs Carpel or pistil female reproductive organs; contains: Stigma is where pollen sticks to Style is the long tube that connects stigma to ovary Ovary enlarged structure at the base of carpel/pistil where the ovules are located; it will become the fruit. Ovules contains female gametophyte, becomes the seed Ovary مبيض ميسم قلم carpel or pistil المتاع

10 male organs Stamen male floral organ, consists of: Anther part of the stamen that produces pollen Filament stalk-like structure that holds anther Pollen immature male gametophyte متك خيط سداة

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14 Plants - Flowers types Perfect- bisexual-hermaphrodite: Both pistil and stamen. Staminate flower: contain stamen no pistil Pistillate: contain pistil no stamen

15 Flowers types - reproductive Monoecious plant/crop: plant has staminate and pistillate flowers Dioecious crop: plants having either only male or only female flowers

16 pollination The transfer of pollen from the anther (male) to the stigma (female) Self-pollination (Autogamy) : Pollen from one flower pollinates the same flower or other flowers of the same plant. Self-pollination may include autogamy, where pollen moves to the female part of the same flower (this). geitonogamy, when pollen is transferred to another flower on the same plant.

17 Cross-pollination (allogamy): Pollen from one flower pollinates flower of another plant. Pollinator: The agent (vector) that moves the pollen Biotic: bees, flies, bats, moths, or birds. Abiotic: wind, water Pollinizer: The plant that serves as the pollen source for other plants.

18 Advantages of self pollination Insures seed set in absence of pollinators. Overcomes sterility. Selectively advantageous by transmitting both sets of genes to offspring. Well-adapted genotypes preserved. Only single colonizing individual needed.

19 Disadvantages of self pollination Decreases genetic variability. Inability to adapt to changing conditions. Increases inbreeding depression. Reduces heterozygosity and increases homozygosity of deleterious alleles. More uniform populations.

20 Factors affect pollination Perfect flowers have both male and female organs Cleistogamy : Flowers never open and only capable of self-fertilization. Chasmogamous: flowers that open and are then pollinated. Timing: Male and female organs mature at different times Temporal separation of reproductive parts (Dichogamy) Protandry(anther first). Protogyny

21 Factors affect pollination Biochemical: chemical on surface of pollen and stigma/style that prevent pollen tube germination on the same flower (Gametophytic and Sporophytic incompatible) Physical separation of reproductive parts Morphological: Heterostyly: Distyly (Trum and pin flowers). Tristyly Separation of flowers: Unisexual flowers. Monoecious and Dioecious. Trum Pin

22 Self vs. cross Self compatible Small flowers (few) Unscented flowers Nectaries & nectar guides absent Maturation of reproductive parts Anthers near stigma Style included All fruits mature Low pollen/ovule ratio Self compatible and incompatible Large showy flowers (many) Scented flowers Nectaries & nectar guides present Differential maturation of reproductive parts Anthers far from stigma Stigma well-exserted Only some fruits mature High pollen/ovule ratio

23 Pollination and Fertilization pollen delivered to the stigma (pollination). Pollen sticks to the stigma, starts growing a pollen tube Fertilization begins when tube begins to grow toward the egg Double fertilization.

24 Pollen contains TWO nuclei: a sperm nucleus and tube nucleus Sperm nucleus is protected in gametophyte tissue

25 Double Fertilization Double fertilization occurs: One sperm nucleus (1n) fertilizes the egg, producing a zygote (2n) which becomes the plant embryo inside the seed Another sperm nucleus fuses with the polar nuclei, resulting in a triploid endosperm (3n) Endosperm is a source of food for the young embryo. Endosperm

26 Hybridization It is a common way of generating genetic variability. As an example of the power of hybridization in creating variability, Cross between hypothetical wheat varieties differing by only 21 genes Capable of producing more than 10,000,000,000 different genotypes in F2 More than 100,000 dunum (10cm*10cm) would be required to grow them. Majority of F2 are heterozygous genotypes for one or more traits Statistically it is possible that 2,097,152 different homozygous genotypes can occur, each potentially a new pure-line variety. These illustrate the importance of efficient techniques in managing hybrid populations.

27 Hybridization technique. Pollinate the female parent flower with pollens from the required male parent and prevent any other source of pollens. Easiest in dioecious crops. Moderate in monoecious. Could be very hard in plants with perfect flowers. o The techniques require skilled hands. o First step in hybridization is to ensure that no pollination takes place before done artificially. o The process involves the bringing of the stigma and pollen of different plants together. They should be combatable and at proper stage of maturity. o Selected parents should be combatable.

28 Hybridization technique. Emasculation of perfect flower and used as female flower: Artificial Pollination: Rising of hybrids: Emasculation of perfect flower: Physical removal of the anthers in self- pollinated plants. The female flower is ready As a rough guide, an experienced person takes a good ten minutes to remove all the anthers from wheat spike.

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30 Bagging: After emasculation, female flowers are enclosed in bags to avoid getting pollens from undesired sources. Bagging is done with special paper or polyethylene Labeling properly the emasculated flowers.

31 Artificial Pollination: Pollens from the selected male plants are collected in suitable containers (paper bags, tubes or dishes) Dusted with a fine brush, on to the receptive stigma of the female parent. Or Direct contact between mature anthers and stigma Female flower is securely sealed in a bag till the time of seed setting.

32 Rising of hybrids: Seeds are collected from the fertilized plants (F1 seeds) Handel the F1 seeds Sell Produce pure line..

33 Emasculation: No emasculation Male sterility Self incompatible Monoecious Dioecious

34 Chemically induced male sterility Male sterility is induced by some chemicals eg. dichlorophenoxy acetic acid maleic hydrazide in wheat Emasculation: Where physical removal of anthers is not possible. Genetic Male Sterility. Cytoplasmic genetic male sterility. Male sterility is controlled by the interaction of a genetic factor (S) present in the cytoplasm and nuclear gene (s). Environment-sensitive genetic male sterility. Male sterility is controlled by nuclear gene expression, which is influenced by environmental factors such as temperature. eg. Dipping panicle in hot water (50 c) for 10 minutes. practiced in Sorghum

35 Timing: Hybridization involves the bringing of the stigma and pollen of different plants together. Synchronize flowering Plant a set of parents at different times photoperiod in photoperiod sensitive species. Delay, Advance Manipulation of temperature Plant density Irrigation Removal of old flowers, induce new flush of flowers Pinching. To induce tillering or branching with new flowers. Store of pollin grains

36 Emasculation and pollination movies: mtc GRU Information Resource 1- Guide to how to cross peas.wmv GRU Information Resource 2- Guide to how to emasculate wheat florets.wmv GRU Information Resource 3- Guide to how to pollinate wheat florets.wmv

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38 HYBRIDIZATION Faddel Ismail NCARE June,