Genetics and Plant Breeding

A trait is a specific characteristic or feature of an organism, such as eye color or height, which can vary between individuals.

Gregor Mendel famously used pea plants (Pisum sativum) for his experiments because they were easy to grow, had distinct traits, and could be cross-pollinated easily.

Heredity is the biological process by which genetic information is passed from parents to their offspring, determining their traits.

Heredity is the passing of genetic information from parents to offspring, a fundamental process that occurs in all living organisms, including plants, animals, and bacteria.

Heredity is the biological process by which genetic information is passed from parents to offspring. Photosynthesis is the process plants use to make food, and pollination is the transfer of pollen.

Inherited traits are characteristics passed down through genes from parents to their offspring. They are not chosen by the organism or created randomly.

Germplasm refers to the living genetic resources, such as pollen, seeds, or tissue, that are kept for the purpose of animal and plant breeding, preservation, and other research uses. Thus, it represents both preserved genes and preserved cells.

In a Mendelian monohybrid cross, crossing two heterozygous individuals (Tt x Tt) results in an F2 generation with a genotypic ratio of 1:2:1. This represents 1 homozygous dominant (TT), 2 heterozygous (Tt), and 1 homozygous recessive (tt) offspring.

Male 2n -> gamete n. Female 4n -> egg 2n, polar nuclei 2n+2n. Embryo = 2n (egg) + n (sperm) = 3n. Endosperm = 2n+2n (polar) + n (sperm) = 5n.

Monoecious plants have male and female flowers on the same plant. This arrangement prevents autogamy (self-pollination within the same flower) but does not prevent geitonogamy (pollination between flowers on the same plant).

Continued self-pollination leads to the accumulation of recessive deleterious alleles, resulting in a reduction in fitness known as inbreeding depression.

Polygenic traits are those controlled by two or more genes. Most complex human traits, such as height or skin color, are influenced by multiple genes working in combination.

Homozygous means an organism has two identical alleles for a particular gene. Heterozygous means the alleles are different.

In sexual reproduction, an organism inherits one set of chromosomes (and thus one copy of each gene) from each parent. This results in a diploid state where there are two copies of each gene total.