science

Late-acting self-incompatibility

Late-acting self-incompatibility is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Late-acting self-incompatibility rather than just read about it. In short: Late-acting self-incompatibility (LSI) is the occurrence of self-incompatibility (SI) in flowering plants where pollen tubes from self-pollen successfully reach the ovary, but ovules fail to develop. Mechanisms that might cause late-acting self-incompatibility have yet to be elucidated.

Key takeaways

Late-acting self-incompatibility belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Late-acting self-incompatibility to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Late-acting self-incompatibility from memory before moving on to harder problems.

Reference excerpt

Late-acting self-incompatibility (LSI) is the occurrence of self-incompatibility (SI) in flowering plants where pollen tubes from self-pollen successfully reach the ovary, but ovules fail to develop. Mechanisms that might cause late-acting self-incompatibility have yet to be elucidated. One hypothesis is that the occurrence of LSI is caused by early-acting inbreeding depression where the expression of genetic load causes self-fertilized embryos to abort.

Advantages and disadvantages of LSI The proposed advantages of LSI compared to normal SI mechanisms is that LSI would allow the maternal parent to evaluate the paternal genetic material and allow ovule development depending on the vigor of developing embryos or amount of resources available. On the other hand, plants with LSI may face a disadvantage from seed discounting, which results in a reduction in fecundity. When pollen tubes reach the ovule, they are no longer available to be fertilized by outcrossed pollen, meaning LSI still uses up ovules for potential outcrossing while other SI methods do not.

Evidence supporting LSI Since LSI reactions are said to occur in the ovary and ovules, it is more difficult to researchers to determine where LSI reactions may occur to assess possible LSI mechanisms. Conventional SI reactions are much easier to observe, because they occur in the style or on the stigma. However, research has provided some evidence for the existence of late-acting self-incompatibility. Species noted to possibly have LSI form phylogenetic groupings in a similar fashion to how conventional SI is shared in other phylogenetic groups, suggesting that LSI may be derived from a common ancestor. A study by Lippow and Wyatt reported that species that have LSI create offspring that can be split into different groupings of compatibility and incompatibility based on Mendelian inheritance, which is something that can be demonstrated with plants that have typical SI mechanisms. It is also reported that some plants lack conventional SI mechanisms, yet ovules failed to develop at all, which is unexpected if the mechanism were to be due to lethal alleles.

Evidence against LSI and alternative explanations Studies have reported evidence against LSI and have proposed alternative explanation. For example, some species that are expected to have LSI display abortion at various stages of seed development, indicating that the abortion was due to selective embryo abortion caused by early-acting inbreeding depression. Another explanation for LSI is that it is the occurrence of gametophytic self-incompatibility, but self-pollen tubes are slowed to the point where they do not achieve fertilization prior to ovule abortion.

References

Worked examples

Example 1 — a first encounter with Late-acting self-incompatibility

Start with the simplest possible case. Write down what Late-acting self-incompatibility claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Late-acting self-incompatibility before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Late-acting self-incompatibility ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Late-acting self-incompatibility

In research: Late-acting self-incompatibility appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Late-acting self-incompatibility in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Late-acting self-incompatibility is common in secondary-school and first-year university syllabi. It links to neighbouring topics Plant reproduction, so understanding it makes those chapters shorter.
In everyday life: Look for Late-acting self-incompatibility outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Late-acting self-incompatibility in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Late-acting self-incompatibility means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Late-acting self-incompatibility out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Late-acting self-incompatibility in simple terms?

Why does Late-acting self-incompatibility matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Late-acting self-incompatibility?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Late-acting self-incompatibility.