Domestication 4 Flashcards
Maize branching
Gene responsible is TB1 on chr1
TB1 expression reduced branch formation
Encodes a bHLH trans factor that is part of TCP trans factor family
Mutation in TB1 70,000bases upstream from TB1 gene
Maize domestication
Done 9000 years ago in Mexico
Has 13QTL 6 are responsible for change to maize
Teosinte and maize can still be crossed even though they look different
Teosinte has hard outer case that cannot be digested by animals
Architecture in maize
Controlled by TGA1 gene on chromosome 4
TGA1 encodes an SLP trans factor
Point mutation K6N- lys- arg which is charged-uncharged
K6N mutation enhanced by L5F mutation - lys-phe
Western blot showed K6N caused lower TGA1 levels in maize, thought to make protein unstable
Turns out that NOT-1 is another trans factor 98% similar to TGA1 and both appear in the western bot
TGA1 represses NOT-1 and K6N makes TGA1 a better depressor
Less protein in maize due to less NOT1, TGA1 levels stay the same
QTL
Quantitative trait loci
How to conduct QTL
Self f1 population, mosaic chromosomes form due to recombination
Parental polymorphisms between mother and father act as markers
Genes of interest should link to marker 100%
Peaks on a graph show the level of linkage of the marker and the trait
Male flower gametes
Formed by meiosis of mother cell forming 4 haploid megaspores
Each megaspores is a pollen grain
Pollen lands on stigma and forms a pollen tube if compatible
Female flower gametes
Mother cell undergoes meiosis to produce 4 haploid cells
3 haploid die and 1 megaspores survives
Megaspores undergoes meosis to form 8 nuclei in 1 cell
Cell compartmentalises into 7 and the central cell is diploid
Flower fertilisation
Double fertilisation event
First fertilisation, sperm meets egg forms an embryo
Second fertilisation, second sperm enters endosperm which provides nutrients to embryo
Flower whorls
1- sepals
2-petals
3-stamen
4- carpels
