Reproduction and plant Breeding B K Auti Radhabai

Reproduction and plant Breeding B K Auti Radhabai Kale Mahila Mahavidyalaya, Ahmednagar. 1

Flowering and Pollination n n Two major plant classifications are the Gymnosperms and the Angiosperms. These include flowering plants, grasses, and cereals. 2

Flowering and Pollination n n All angiosperms develop flowers which contain one or more ovules that are enclosed in an ovary or carpel. The flower is the reproductive structure for the angiosperms. 3

Flowering and Pollination A flower is complete if it has all four of the following structures: Sepals, Petals, Stamens, and a Carpel (pistil) n 4

Flowering and Pollination n An incomplete flower lacks one or more of the before mentioned structures. 5

Flowering and Pollination n n A flower that has both stamens (male reproductive tissues) and a carpel (female reproductive tissues) is a perfect flower. Imperfect flowers have either stamens or a carpel, but not both. 6

Flowering and Pollination n The sepals and petals help to attract insects to the plant by producing a sugary solution called nectar. 7

Flowering and Pollination n n An incomplete flower is one which has no sepals or petals. Most cereal and grass plants have incomplete flowers, which makes the flowers less visible. 8

Flowering and Pollination n n Flowering is initiated by: Length of uninterrupted darkness (photoperiodism) Exposure to low temperatures (vernalization) Morphological maturity (able to produce seed) 9

Flowering and Pollination n n The majority of food-producing plants induce flowering without external stimulation. As long as they are actively growing, they initiate flowers at almost any temperature or day length. 10

Flowering and Pollination n n The Stamen, consists of the Anthers and their supporting filament. The development of pollen grains (microspores) occurs in the Anthers. 11

Flowering and Pollination n As the Anther matures, they break open and pollen grains are spread by the wind and insects. 12

Flowering and Pollination n The Carpel, includes the Stigma, Style, and Ovary. The Stigma is the swollen end of the Style, is colorful and allows for the pollen to stick. Pollen grain must land on the Stigma in order for pollination to occur. 13

Flowering and Pollination n n Self-pollination occurs when the anther and the stigma are from the same flower. From different flowers on the same plant. From different plants of the same cultivar or variety. Cross-pollination involves different flowers on plants or different cultivars. 14

Flowering and Pollination n n Some plants are self-fertile and produce fruit and seed without the transfer of pollen form another cultivar. Most monocot plants. 15

Flowering and Pollination n A plant is considered self-sterile if it requires pollen from another plant in order to set fruit. Sterility is due to the protien composition of the cell of wall of pollen grains. The protein sends a signal to the stigma indicating whether the pollen is from its 16 own species or the same plant.

Flowering and Pollination n n Each pollen grain contains a tube cell and a generative cell. When the pollen lands on the stigma, germination occurs. 17

Flowering and Pollination • The tube cell forms a pollen tube that grows through the stigma and style. n The pollen tube enters the nucleus of the ovule by passing through the Micropyle 18

Flowering and Pollination n The generative cell has produced two male gametes through the process of Mitosis. 19

Flowering and Pollination n One gamete unites with the egg cell to form the Zygote, which form the embryo. The other male gamete unites with the polar nucleus in the ovule to form the endosperm. The endosperm the seeds food reserve for germination. 20

Flowering and Pollination n n The time between pollination and fertilization in most angiosperms is 24 to 48 hours. Once fertilization has occurred, the ovule becomes the seed and the ovary becomes the fruit. 21

Plant Breeding n n n Hybridization: the crossing of two plants that have different genotypes. Crossbreeding usually produces a plant that is more vigorous in growth that either of its two parents. Hybrids do not pass many of their traits to their offspring, so parent stocks must be crossed each year to produce new 22 seed.

Plant Breeding n n n The production of hybrid seed is managed by production organizations. Growers are under contract to grow the parent lines and make the hybrids. Seed production fields must be isolated from other fields to prevent unwanted cross-pollination. 23

Plant Breeding n n When tassels begin to emerge, the female plants are detassled to prevent selt-pollination. The wind then cross-pollinates the male parent with the female to produce hybrid seed. 24

Plant Breeding n n Single Cross Inbreeding: the Inbred parent A x Inbred Parent B process of Single cross Ax. B crossing two similar parents. After inbreeding Three Way Cross five to seven Inbred parent A x Inbred Parent B generations, Single Cross Ax. B x Unrelated Inbred C certain Three-way cross (Ax. B) x C phenotypes will be expressed. 25

Plant Breeding n Backcrossing: offspring are continously crossed with one of the parents. 26

Biotechnology Techniques n n n Biotechnology: the management of biological systems for the benefit of humanity. Biotech uses molecular biology and molecular genetics for developing plant breeding methods. These include: tissue culture, protoplast fusion, embryo manipulation, 27 recombinant DNA.

Biotechnology Techniques n n Micropropagation: the propagation (asexual) of plant cells or tissues in a closed container. Cell culture: modifying the genetic makeup of the cell and then regenerating plants with desired traits. 28

Biotechnology Techniques n n Microinjection: the mechanical insertion of genetic material into a single, living cell. Cell walls can be dissolved using enzymes. This exposes the cells protoplast. This allows the genetic makeup of different plants to be fused together. 29

Biotechnology Techniques Recombinant DNA or genetic engineering involve; 1. Gene splicing 2. Replication 3. Transfer of genes to other organisms Transgenic organisms would carry in their cells a foreign gene. n 30

Biotechnology Techniques 1. Starts with cutting gene with an enzyme. 2. The sliced gene is then removed and inserted into a circular DNA molecules called plasmids found in bacteria. 31

Biotechnology Techniques 3. An enzyme is used to seal the spliced ends. 4. The DNA plasmid is inserted into a cell selected for alteration. 5. The result is a new sequence of DNA. 32