This document summarizes research investigating genomic regions that control maturity in maize (Zea mays L.) using an advanced backcross-derived population. Key findings include: 1) A quantitative trait locus (QTL) on chromosome 8 was found to be strongly associated with days to pollen shed, days to silk emergence, and grain moisture at harvest. 2) Additional QTL for plant height and node number were also mapped to chromosome 8. 3) Evidence of epistatic interactions was observed between the QTL on chromosome 8 and other regions on chromosomes 1 and 5, influencing the traits of interest.

1. INVESTIGATION OF GENOMIC REGIONS CONTROLLING
MATURITY IN MAIZE (ZEA MAYS L.) USING AN
ADVANCED BACKCROSS-DERIVED POPULATION

2. Maturity in Maize
Several definitions of maturity:
-Days from planting to anthesis (pollen shed)
-Days from planting to silk emergence
-Percent grain moisture at harvest
-Physiological maturity of the kernel (black layer formation
and attainment of maximal kernel dry weight)

3. E
E
E
N
N
N
N E
G 1 25
26 39
1 26
27 41
Early F2s
Late F2s
EcoRV
Selective Genotyping
PG7- RAPD derived marker
Chromosome 8
G=Gaspe Flint
E=N28E
N=N28

4. What is a Quantitative Trait Locus (QTL)?
Genes whose phenotypic effects are influenced by other genes (epistasis) and the environment.
Phenotypes are scored on a scale (flowering time, height, weight, etc.)
Importance extends to agriculture, medicine, evolution, environment
How does the use of QTL methodology change how quantitative genetics is done?
Traditional: Study combined effect of ALL genes affecting a quantitative trait (en mass).
Partition variance into E and G
Partition G into A and D/E
Predict H2 (effect of selection)
With the help of molecular techniques:
Allows one to map individual genomic regions controlling the trait of interest.
Enables one to estimate the position of gene(s), size of effect,
and type of gene action.
With different types of populations, faster PCR based methods, and better
biochemical information, possible biological implications can result
Perhaps better suited for planning schemes in plant breeding sense (Caution!)
Summary:
Just about any gene can be thought as a QTL

5. Quantitative Trait Loci (QTL) Analysis Using
Molecular Markers (RFLPs) in an F2
Population
P1 P2 F2s
Locus A: Associated with maturity
Locus B: Not associated with maturity
B1
B2
A1 A1 A1 A2A2 A2
A1
A2
B1 B1 B1 B2B2 B2
Marker Class Means

6. Backcross Derived Line (BDL) Method
for Detecting QTLs Influencing Maturity
DP RP BDLs
Key:
DP- Donor Parent
RP- Recurrent Parent
BDL- Backcross
Derived Line
DP RP BDLs
High probability of
marker linkage with QTL
Unlinked marker
Marker A
Marker B

7. Fig. X Chr. 1, 6, 8. Arrow Indicates Centromere Above. Chr. 6 note- not mapped in this pop-
cM distances from BNL map 1995. NP- not polymorphic but maps to this region.
Telomere
UMC124
DGG9
UMC89
CSU31
PIC6
CSU66c
CSU66b
BNL8.26
UCBanp1
PGE11, Mu2
PG7
ZmHox1a
UMC12
CSU33b
UMC84
UMC160a
NPI280
Chr.1 Chr. 6 Chr. 8
ZmHox1a (NP)
5 cM

9. Average Height Data
N28 X N28E F3
1994 and 1995
0
5
10
15
20
25
30
123.5
127.5
132.5
137.5
142.5
147.5
152.5
157.5
162.5
167.5
172.5
Centimeters
Frequency
N28E
136.52 +/-5.94 cm
n=40
F1
158.31 +/-7.09
cm
N28
170.48 +/-7.00 cm
n=37

10. Average Node Number
N28 x N28E F3
1994 and 1995
0
5
10
15
20
25
30
35
10.5 11 11.5 12 12.5 13 13.5 14 14.5 15 15.5 16
N28E
11.74+/-0.75
F1
13.20+/-0.92
N28
14.54+/-0.73

11. Qualitative Trait- Single recombinant on either side of the gene
defines location.
Quantitative Trait- Recombination helps to define a support interval
but with the rest of the genome segregating and with influences of epistastic
interactions, precise gene locations are not possible. (Show lod curve)
Complex traits do not show perfect cosegregation with any single locus:
incomplete penetrance/phenocopy/genetic heterogenity/polygenic inheritance
(Lander and Schork, 1994)
Fig. Kriglyak and Lander, Am. J. Hum. Genet.
56:1212-1223, 1995

12. Chromosome 8L
LOD Score Distribution for DPS
IM Method
UMC124
DGG9
UMC89
CSU31
PIC6
CSU66c
UMC12A
CSU66b
BNL8.26
UCBanp1
PGE11,Mu2
PG7
LOD
1994
1995
0
5
10
15
20
25
30
35
40
45
50
Zmhox1a

13. UMC124
DGG9
UMC89
CSU31
PIC6
CSU66c
UMC12A
CSU66b
PGE11,Mu2
PG7
Zmhox1a
Ucba11
BNL8.26
1994
1995
DPS QTL Mapping Results
CIM 1994 and 1995
Chromosome 8
0
2
4
6
8
10
12
14
16
18
0
4
8
12
16
20
24
28
32
36
40
44
48
52
56
60
64
LODScore
1994
1995

14. LOD Score Distribution for GDU ‘95
Chromosome 1L
UMC84
CSU33b
LOD
0
0.5
1
1.5
2
2.5
3

15. Height QTL Mapping Results
CIM Combined Data 1994 and 1995
Chromosome 8
0
5
10
15
20
25
0
4
8
12
16
20
24
28
32
36
40
44
48
52
56
60
64
LOD
UMC124
DGG9
UMC89
CSU31
PIC6
CSU66c
UMC12A
CSU66b
PGE11,Mu2
PG7
Zmhox1a
Ucba11
BNL8.26

17. Node Mapping Results
sCIM Combined Data 1994 and 1995
Chromosome 8
0
2
4
6
8
10
12
14
16
0
5
10
15
20
25
30
35
40
45
50
55
60
LODScore
UMC124
DGG9
UMC89
CSU31
PIC6
CSU66c
UMC12A
CSU66b
PGE11,Mu2
PG7
Zmhox1a
Ucba11
BNL8.26

18. Threshold for a 5% experiment-wise error rate
Twelve Nonsense DPS Data Permutations
95% of Data Scans Remain Below the 2.4 LOD
Score (Experiment wise)
0
0.5
1
1.5
2
2.5
3
3.5
0
5
10
15
19
22
27
32
37
42
47
51
56
61

19. Epistatic Genotypic Values
GDU 1995
-10
-5
0
5
10
15
ZmHOX1a E ZmHOX1a H ZmHOX1a N
Marker Class
GDU
CSU33b E
CSU33b H
CSU33b N
Total Genotypic Values
GDU 1995
730
740
750
760
770
780
790
800
810
820
830
ZmHOX1a E ZmHOX1a H ZmHOX1a N
Marker Class
GDU CSU33b E
CSU33b H
CSU33b N

20. Total Genotypic Values
Combined Height Data '94 and '95
130
135
140
145
150
155
160
165
UMC89
E
UMC89
H
UMC89
N
Marker Class
Centimeters
CSU33b E
CSU33b H
CSU33b N

21. Maturity QTL Regions
with Related Duplicated Loci
Probes Originating from the Chr. 8L region
Chr. 1L*
Chr. 3L*
Chr. 6L*
Chr. 8L*
UMC89b
UMC89a
UMC160a
UMC160b
Bnl12.30b
Bnl12.30a
Zmhox1a Zmhox1b
UMC2c
UMC2a
Pic6b
Pic6a
MWG645j
MWG645a
Bin 1.06
Bin 3.08-9
Bin 6.06
Bin 8.04-5
uiu(pog1a)
UMC184c
uiu(pog1c)
UMC184d
Reference-
*Chr.1.06-Ragot et al. 1995 and 3 others
*Chr.1.11- Present plus 4 others
*Chr.5-Kim,1992; Mori, 1995
*Chr.3-Ambler et al. 1991
*Chr.6-Veldboom et al. 1994; Koester et al. 1993
*Chr.8-Kim,1992; Vladutu,1996
CSU33b
Bin 5.00-Height
CSU33a
Bin 1.11

22. Epistatic Genotypic Values
Combined Height Data '94 and '95
-2
-1.5
-1
-0.5
0
0.5
1
1.5
2
2.5
UMC89 E UMC89 H UMC89 N
M arker Class
Centimeters
CSU33b E
CSU33b H
CSU33b N

23. Mapping of Maturity QTLs
UMC5
UMC139
CDO1328
UMC160
ZmHox1
RZ776
BNL12.30
Sorghum* MaizeBin
Chr. 2
Chr. 7
Chr. 2
Chr. 10
Chr. 6
Chr. 8
Chr. 3
Chr. 8
2.05
10.05-6
2.06-8
7.02-4
6.06
8.04
3.07-9
8.05-7
LG B
LG D
LD G
Reference- *Lin et al. 1995
Koester et al. 1994
Ragot et al. 1995
Veldboom et al. 1994
Beavis et al. 1994
Koester et al. 1994
Koester et al. 1994
Ragot et al. 1995
Koester et al. 1994
Not significant

24. Acknowledgements
Dr. Ronald Phillips
Cristian Vladutu
Mike Olsen
Naoki Mori
Roberto Tuberosa
Shahryar Kianian
Oscar Riera
Jonathan Shaver
Suzanne Livingston
Jayanti Suresh
Lisa Gulbranson