Summary
Summary Course 9 Plant Biology term 2
- Module
- Institution
- Book
Summary of the Biology theoretical lessons in term 2 of course 9. Books iGenetics and Plant Biology are used for additions.
[Show more]
Connected book
Book Title:
Author(s):
- Edition:
- ISBN:
- Edition:
More summaries for
-
RNA, transcription and processing
-
Gene expression and post-transcriptional modification
-
Genomes and recombination
Seller
Follow
kimjon
Reviews received
Content preview
Plant biology course 9 term IILecture 1 classical & modern breeding
Main breeding goals
- Increased biomass accumulation
- Increased harvestable yield
- High nutritional quality
- Resistance to pests
• Not allowed to use all chemicals → environment
- Performance in high stress environments
- Plant architecture
- Photoperiod response
• Plant producing tubers or flowering
- Processing characteristics
• Starch quality in potato
- Dormancy suppression
• Cold treatment induces flowering → reducing time period for more yield
Basic steps in plant breeding
1. Creation of variation
2. Selection
• Can take long time
3. Evaluation
4. Release
• Private producer/ firm for further commercial testing
• Quality criteria = DUS (distinctness, uniformity and stability)
5. Multiplication
6. Distribution of the new variety (formal release)
1 to 10.000 species to come to evaluation will pass next steps
Creation of variation
1
,Finding variation
- Centers of origin of crop
• Lot of variation in one crop
• 8 major centers
Polyploid crops
- More sets of chromosomes than 2 → polyploid
- Plants have bigger cells, bigger organs so bigger plants
• Also bigger fruits so favourable
- Polyploid crops can be sterile (useful in seedless fruits like banana)
2
,Allopolyploidy vs autopolyploidy
- Allopolyploidy
• Mating of 2 different species
- Autopolyploidy
• n chromosome sets from the same species
Hybrid vigour/ heterosis
- 1908: Shull, plant breeder, reported results of crossing maize plants from 2 different inbred
lines
• Inbred lines: 20 bushels of maize per acre, outbred offspring produced about 80!
• This strength in the heterozygous outcross is called hybrid vigour
- Heterosis is the superior performance of hybrid organisms compared with either of their
parents
• In colour, in mass, in flavour etc.
Genetic basis of heterosis
- Suppose that the gene combination AaBb is desirable for a hybrid F1
• Can be achieved by crossing 2 inbred lines: aaBB x AAbb
- AaBb is sold to farmers
- Which percentage of F1xF1 offspring has the desirable gene combination?
3
, - Bad news for farmers, but good news for seed supplying companies!
Hybridization
- Self-incompatibility
• Many angiosperms have mechanisms that make it difficult/ impossible for a flower to
self-fertilize
▪ Unisexual flowers → dioescious species
▪ Containing stamens and carpels that mature at a different time
Pollination systems for crops
- Self-pollinating crop
• Primarily homozygous
• Initial hybridization can be difficult
• Varieties: pure line/ inbred line → 1 genotype
- Cross-pollinating crop
• Heterozygous
• Hybridization: difficult to prevent unwanted pollen from fertilizing the parent
• Varieties: hybrid or populations (mixtures of heterozygous plants)
Self-pollination consequences
- Self-fertilization can lead to inbreeding depression (= antithesis of hybrid vigour)
• Reduction or loss in vigour and fertility as a result of inbreeding (e.g. self-fertilization)
- Many plant species can prevent self-fertilization:
• Pollen separated from stigmas in space or time
• Self-incompatibility (SI)
4
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller kimjon. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for £4.05. You're not tied to anything after your purchase.
Can Stuvia be trusted?
4.6 stars on Google & Trustpilot (+1000 reviews)
83637 documents were sold in the last 30 days
Founded in 2010, the go-to place to buy revision notes and other study material for 14 years now