Hort 1001 Lecture 12

Sexual reproduction: Seeds or spores are used

Asexual (vegetative) reproduction: Manipulation of various plant parts, including cuttings from leaves, roots and stems or grafting.

Results in offspring that are an exact genetic copy of the parent plant that donates the vegetative parts in propagation. Exceptions through mutations are very rare. Environmental conditions can play a role in differences between parent and offspring.

Phenotype: The way the plant looks and performs in an environment.

Genotype: Collection of genes the plant contains.

True

True

Apomixis: Form of asexual reproduction disguised as sexual reproduction. It occurs when an embryo develops solely from maternal tissue with no fusion of egg and sperm. Male and female gametes fuse together. Progeny are identical still since it is asexual reproduction.

Propagation of the plant: Done by embryo, which is the young plant resulting from combination of genes from male sperm transmitted by pollen to the female egg in an ovule.

Nutrient storage: Nutrients fuel growth of the embryo.

Protection: Embryo and nutrient source have a tough covering for protection from the environment and predators (called a seed coat or testa).

Eggs in ovule (located inside ovary) are fertilized by sperm in the form of pollen.

Embryo Axis: Mature seeds have linear arrangement of parts comprised of root and shoot.

Plumule

Point of Attachment

Epicotyl

Hypocotyl

The first true leaves seen. They emerge from the seed and rise above the soil surface to collect energy from the sun.

Location where cotyledon attaches.

Portion of the embryo axis above the point of attachment.

Hypocotyl: Portion of the embryo axis below the point of attachment.

Radicle

Embryonic root tissue.

At the tip of the epicotyl, an apical meristem produces new nodes and internodes.

If you count nodes on the embryonic axis, the first node on the stem starting from the point of transition of root to shoot is the point where cotyledons attach. The second node is where the plumule attaches.

Double fertilization: When angiosperm pollen grains can hold two sperm cells; one of which fertilizes the egg and one of which forms the endosperm.

Endosperm: Forms when sperm cells unite with maternal nuclei (polar bodies).

Coleoptile: Sheath covering the plumule and epicotyl.

Coleorhiza: Sheath covering the radicle.

Coleoptile and coleorhiza are terms used specifically with plants in the grass family and not in other families.

Coleotile and Coleorhiza

Embryo: Propagates new plant.

Endosperm: Provides energy and nutrition.

Pericarp: Protects everything inside.

Carbohydrates: Provide energy from breakdown of molecules made of carbon, hydrogen and oxygen (ex: starch and sugar).

Protein: Sources of amino acids for production of enzymes and nitrogen rich compounds.

Amino acids: Building blocks of proteins.

Vitamins

Lipid: Plant oils in the form of triglycerides are more compact ways to store energy than starch and sugar. Solid lipids are fats.

Fatty, saturated fatty and unsaturated fatty

Fatty acids: Long chains of carbon atoms with two hydrogen atoms attached to each carbon, except when double bonding occurs. In the case of a double bond, each carbon involved in the double bond has only one hydrogen attached.

Saturated fatty acids: No double bonds in chain and all carbon atoms in the interior have 2 attached hydrogen atoms.Animal fats tend to be saturated and solid at room temperature.

Unsaturated fatty acids: One or more double bonds between carbon atoms. They lack hydrogen atoms and therefore are not saturated (unsaturated) with hydrogen.Plant oils tend to be unsaturated and liquid at room temperature as a result.

CIS Fatty Acids: Hydrogens attached to the carbon atoms participating in the double bond are both on the same side of the carbon change (kinked at site of double bond).

Trans Fatty Acids: Hydrogens attached to opposite sides of the carbon atoms participating in the double bond with no kink.

FALSE:Trans fats are NOT naturally occurring and they are the product of hydrogenation. This causes CIS double bonds to transform into trans double bonds and can cause heart disease.

Oilseeds: Legumes with high protein, high lipid and low carbs that can be squeezed (ex: soybean and peanut).

Pulse: Legumes with high protein, low lipid and high carbs. Very important in developing regions where meat is scarce or expensive.

Dicots have cotyledons whose function is storage (especially protein).

In monocots, the cotyledon is primarily used for absorption (high amounts of starch and sugar, low amounts of protein and oil).

Legume seeds are high in protein while cereal grains like corn and rice are high in starch.

Omega 3: The first double bond occurs at the third carbon atom.

Omega 6: The first double bond occurs at the sixth carbon atom.

Seed Coat

Pericarp

Seed coat: Originates as ovule wall tissue.

Pericarp: Originates as ovary wall tissue.

Ovary is at the base of the carpel and holds ovules. Ovules are protected by ovary and hold the egg.

True

Results in sperm uniting with egg and resulting zygote forms embryo and the other sperm pairs with polar nuclei to form endosperm. Cells in ovule multiply and grow.

Integument tissue: Ovule wall made up of maternal cells that mature to become seed coat (like the tan skin on a peanut).

Pericarp: Ovary wall matures into protective cover called pericarp (like the shell of a peanut).