Correlation Between Early Phenotypes and Survival Rate for Commercial Maize

Lines and Fusarium graminearum

Objectives

1. We will evaluate if the maize genotype and/or fungal genotype determines the plant’s level of resistance to F. graminearum infection.

2. We will determine if seedling height, sheath elongation, third leaf emergence, or root length is correlated with survival rate and can be used as a predictor of disease severity.

Methods

D9:• Total root length is the sum of the primary

root length and length of all lateral roots, measured with the RootReader 2D software.

D3, D5, D7,D9:• Sheath length is the distance

between the crown root emergence point and band marking where the cotyledon splits off from the stalk.

• Seedling height is the distance between the crown root emergence point and tip of the seedling.

• Third leaf emergence is the age at which the distance from the band marking to the tip of the second true leaf exceeds 4 cm.

D14:• Survival rate is the proportion of healthy

seedlings to total seedlings. Healthy seedlings are defined by three criteria:

1. The first and second true leaves are upright and green.

2. The stem is straight and rigid.3. The roots are generally white and do

not show the signs of decay (ex. browning, shrinkage).

third leaf emergence

seedling height

sheath length

Survival rate vs. maize and fungal genotypes

• survival rate vs. fungal isolate (absolute values of data) => discuss general pattern that survival rate heavily affected by fungal isolate’s aggressiveness (supported by NOVA analysis’s p-value) => we need to transform data into numerically ranked– compare Gz & Maize columns for same phenotype (less variation within each fungal isolate)

fungal genotype & maize genotype both contribute to “health”/survival rate, but fungal genotype is more important in determining phenotype

• Excel graph of survival rate vs. fungal isolate (data numerically ranked for each fungal genotype) =>

• Excel graphs of survival rate vs. early phenotypes => discuss potential predictors (supported by R2)

0.80 1.00 1.20 1.40 1.60 1.80 2.000.00

0.20

0.40

0.60

0.80

1.00

R² = 0.197856696444336R² = 0.114489016388204

Seedling Height 3 DPI

Heal

th R

ate

-1.00 -0.80 -0.60 -0.40 -0.20 0.00 0.20 0.40 0.60 0.80 1.000.00

0.20

0.40

0.60

0.80

1.00

R² = 0.211251269018694

Third Leaf Emergence 7 DPI (%)

Heal

th R

ate