Bio 103, Lab 10: Genes, Environment, Selection

Crystal Reed and Eri Koike

In this lab, we selected four characteristics of the plants (height until the first leaf, height of tallest part of plant, amount of buds on the plant and the stem color and thickness of the stem) in order to determine what factors were influenced by genes, environmental conditions and random genetic variations.

In our first of a series of observations, we counted the amount of buds on the tallest part of the plant. We initially predicted that the environmental conditions (in our case fertilizier) would affect the number of buds.

Wild Type LL HF: 21 buds

Wild Type LL LF: 10 buds

Petite LL HF: 15 buds

Petite LL LF: 10 buds

Through these two observations, we can find that the environmental conditions, which was in our case high vs. low fertilizer, drastically influences the amount of buds on the tallest part of a plant.

Wild Type HL HF: 27 buds

Wild Type HL LF: 9 buds

Petite HL HF: 22 buds

Petite HL LF: 8 buds

Through our additional observations, we found that fertilizer has more of an impact than light and the type of seed. We found that although the standard did tend to have a slightly larger number of buds, there were other instances where the standard had less or the same as the petite. Therefore, we found that the environmental factors (specifically the fertilizer) had more of an impact on the bud phenotype than the genetic factors.

In our next set of observations, we decided to look at the height until the first leaf and the height of the tallest plant. We initially predicted that the type of seed (wild vs. petite) and the environment (High/low fertilizer) would influence the height of the plants.

Changes in High/Low Fertilizer in Low Light:

Wild Type LL HF: (Height until first leaf) 2 in.; (Height of tallest plant) 6.75 in.

Wild Type LL LF: 3.125 in.; 6 in.

Petite Type LL HF: 1.75 in.; 5 in.

Petite Type LL LF: .9375 (15/16) in.; 3 in.

Changes in High/Low Fertilizer in High Light:

Wild Type HL HF: .75 in.; 9.5 in.

Wild Type HL LF: .125 in.; 1.75 in.

Petite Type HL HF: .0625 in.; .1825 in.

Petite Type HL LF: .125 in.; 1.75 in.

In this observation, we found that different environmental conditions work well for the growth of different types of plants. In the wild type plants, the best condition for growth was in high light and high fertilizer. Although we predicted that would be the result for both types of seeds, we found in the petite type that in fact low light and high fertilizer helps it to grow the tallest. For the height to first leaf, we found that it is greatly affected by light but also to a lesser degree by genes.

Therefore, we can state that each plant has its own optimal conditions that it can thrive in.

Our next set of observations has to do with the stem color and thickness of the stems. We initially predicted that the seed type would influence the color and thickness as well as the environmental factors.

Wild Type LL HF: Light green; 3/32 in. thick

Wild Type LL LF: Light purple; 1/32 in. thick

Petite Type LL HF: Dark purple; 2/32 in. thick

Petite Type LL LF: Medium Purple; 1/32 in. thick

Wild Type HL HF: Medium Green; 3/32 in. thick

Wild Type HL LF: Dark Purple; 2/32 in.

Petite Type HL HF: Dark Green; 4/32 in.

Petite Type HL LF: Dark Purple; 1/32 in.

Through this set of observations, we found that the petite type plants tended to be darker in stem shade except when high light was applied to the wild type. So therefore, we can state that the genetics had to do more with stem color than the environmental conditions and the stem thickness was heavily influenced by the environmental factors (since the stem was thickest in the high fertilizer)

And finally, our last set of observations has to do with the number of trichomes on the petiola of the first leaf.

Wild Type LL HF: 3 petiolar trichomes

Wild Type LL LF: 6 petiolar trichomes

Petite Type LL HF: 0 petiolar trichomes

Petite Type LL LF: 0 petiolar trichomes

Wild Type HL HF: 4-6 petiolar trichomes

Wild Type HL LF: 1 petiolar trichomes

Petite Type HL HF: 0 petiolar trichomes

Petite Type HL LF: 17 petiolar trichomes

Through these set of observations, we can conclude that generally, the number of petiolar trichomes has to do with seed type (*There is one outlier to this case in the Petite Type HL LF where there were 17 trichomes.*) and that environmental factors don't have any influence on the number of trichomes.

In this lab we chose three characteristics to compare between the different plants. The data we gathered was of the following eight specimens:

1) LL, S, HF (low light, standard, high fertilizer)

2) LL, S, LF (low light, standard, low fertilizer)

3) LL, P, HF (low light, petite, high fertilizer)

4) LL, P, LF (low light, petite, low fertilizer)

5) HL, S, HF (high light, standard, high fertilizer)

6) HL, S, LF (high light, standard, low fertilizer)

7) HL, P, HF (high light, petite, high fertilizer)

8) HL, P, LF (high light, petite, low fertilizer)

The characteristics we looked at were: the number of petriolar trichomes on the first true leaves, height, and foliage (number of leaves).

Petriolar trichomes on the first true leaves (an average):

1) LL, S, HF: 5

2) LL, S, LF: 1

3) LL, P, HF: 2

4) LL, P, LF: 5

5) HL, S, HF: 4

6) HL, S, LF: 8

7) HL, P, HF: none

8) HL, P, LF: 10

--No correlation that we could find. 

Height (on average):

1) LL, S, HF: 14

2) LL, S, LF: 9

3) LL, P, HF: 11

4) LL, P, LF: 4

5) HL, S, HF: 18

6) HL, S, LF: 3

7) HL, P, HF: 11

8) HL, P, LF: 3

--There is a definate correlation between height and fertilizer: the high fertilizer plants are taller. 

Foliage (number of leaves) (on average):

1) LL, S, HF: 7

2) LL, S, LF: 2

3) LL, P, HF: 4

4) LL, P, LF: 3

5) HL, S, HF: 6

6) HL, S, LF: 1

7) HL, P, HF: 5

8) HL, P, LF: 2

--There is also a correlation between foliage and fertilizer: the plants with more leaves were those with high fertilizer. 

Observations:

LL, S, HF and HL, S, HF are both "droopy;" that is, instead of growing vertically they chose to grow outward, or horizontally, in a curve.

Forty-five minutes into the experiment and all of the high-fertilizer plants are drooping.

HL, P, HF had no trichomes on the petrioles because the leaf directly grew from the main stem of the plant.

Low light yielded taller plants in both varieties, but the stems were slimmer than those of high light plants.  

According to our data, the environmental factors, (namely that of fertilizer), made the most difference on the varying characteristics of the plants. The high fertilizer plants grew the tallest and produced the most foliage, where as the low fertilizer plants were smaller and produced only a sparse amount of foliage.

It is obvious that there is a general difference between the standard and petite plants in terms of height, but it seems that genes only play a basic role in height; fertilizer affected the height of the plants more than the genes. 

Vivian Cruz, Eurie Kim

In this experiment, we tested the traits of height, color, number of flowers (per stem), and petiolar trichromes.

Height
STANDARD
LLSLF 14.9 cm
HLSHF 22.8 cm
HLSLF 8.1 cm
LLSHF 16.2 cm

avg. 15.5 cm

PETITE
LLPLF 4.6 cm
HLPHF 9.2 cm
HLPLF 3.4 cm
LLPHF 13.0 cm

avg. 7.55 cm

*From these observations, we can tell that the plants with STANDARD genes were taller than the plants with PETITE genes (on average). However, there was also variation in height within each gene group. For instance, the plants with HIGH FERTILIZER within each genetic group were taller than those with LOW FERTILIZER.
*This shows that both genetics and the environment play a role in determining height, but genetics lays a foundation for the trait (and from that foundation, depending on the environment the plant would grow taller than others, or not).

Color
STANDARD
lighter-colored leaves
HLSLF - lower-level leaves had reddish tint

PETITE
darker-colored leaves
HLPLF - lower-level leaves also had reddish tint

*Seeing that there is a general color difference between the two gene groups, genetics affect color, however, in both gene groups, the HIGH LIGHT, LOW FERTILIZER plants both had reddish-tinted leaves, showing that the environment could also affects the leaves' color.

Petiolar Trichromes
STANDARD
HLSLF 11 hairs
HLSHF 14
LLSLF 5
LLSHF 5

PETITE
HLPLF 0
HLPHF 0
LLPLF 4
LLPHF 0

*The PETITE plants generally don't have hair with the except of LLPLF, which did have 4 hairs. This shows that there is still variation within a gene group. Furthermore, within the STANDARD group of plants, the HIGH LIGHTS generally had more hair than the LOW LIGHTS, which also shows that the environment could affect this trait.

Our Story
Both genetics and environment affect traits.

The first thing that we observed was the height of the plants. It's largely affected by genes (hense the names "standard" and "petite"). They also seem to vary due to environmental factors. For both sets of plants, we noticed that the plants with the lower amount of light, but higher amount of fertilizer were the tallest, high light/high fertilizer was the second tallest, low light/ low fertilizer was third, and high light, low fertilizer was the shortest.

The plants with more light tended to be shorter, but had more flowers. Even with different amounts of fertilizer, high light plants had more flowers than their counterparts. We concluded that environment is the main factor in the flower.

The flowers were more clustered when the plant had the higher amount of fertilizer for both sets of plants.

For the standard group, these are the numbers of petiolar trichomes (we only took one leaf from one of each of these plants):

High light, high fertilizer- 18

Low light, high fertilizer- 15

High light, low fertilizer- 10

Low light, low fertilizer- 10

The only petite group plant that had these tricomes were the low light, low fertilizer plants. The leaf we looked at had 11 petiolar trichomes.

We were really baffled by the fact that only one set of plants for the petites had these "hairs". The rest seemed to be completely "bald" of these hairs.