Lecture 16: Adapting Development to the Environment Flashcards
Seed germination promoted by
red light (670 nm)
seed germination inhibited by
far-red light (700nm)
flowering is responsive to length of darkness
Short day plants need long night to flower. Long day plants need short night to flower. Plants can integrate time in dark.
Red light can interrupt long night. Far-red is ineffective and can counteract the red light
A phytochrome consists of
two identical proteins joined to form one functional molecule. Each of these proteins has two domains.
- chromophore
- photoreceptor activity
- kinase activity
response to Red/Far-red light depends on
Phytochrome
plants also have photoreceptors sensitive to other wavelengths than red
e.g. cryptochrome
starch-based statoliths at the root tip mediate
gravity response. Feedback to auxin transport cha PIN proteins
Plants respond to signals & produce signals - trophic interactions
caterpillar:
1) wounding
1) chemical in saliva
2) signal transduction pathway
3) synthesis & release of volatile attractants
4) recruitment of parasitoid wasps that lay their eggs within caterpillars
how are signals transducer into a response in plants?
- hormone or environmental stimulus received by receptor (RECEPTION)
- reactions produce second messengers (SIGNAL TRANSDUCTION) -> activated cellular responses (RESPONSE)
signal response involves
both rapid changes in ion channel activity & altered gene expression
Identifying developmental genes using molecular genetics:
- Create mutants with altered phenotype.
- Clone mutated gene responsible for phenotype.
- Examine where and when gene is expressed and what type of protein the gene encodes.
how to make a mutant plant:
-Libraries of seeds are available in which foreign pieces of DNA (called T-DNA) have been inserted throughout the plant genome.
Insertion of T-DNA will probably stop/alter gene function.
-Screen T-DNA library of plants and identify abnormal phenotype.
-The sequence of the T-DNA is known.
It is possible to sequence out of the T-DNA and identify the flanking genomic sequence of the plant
sequence alignment programs allow you to
find your gene in a known genome, or find a similar genes in other genomes
Bioinformatic tools allow you to
find out the likely function of the protein encoded by the gene
Identifying a gene is trivial, identifying the ____ is the challenge for 21st century
Identifying a gene is trivial. Identifying the function of
a gene and how it influences plant growth, development, response to environment, etc. is the challenge for 21st century.
