2010 Annual Report
United States Germplasm Enhancement of Maize Project
Margaret Smith
Department of Plant Breeding and Genetics, Cornell University
Project Title: Anthracnose Stalk Rot Resistance from Exotic Maize Germplasm
Justification:
Anthracnose stalk rot (ASR), caused by Colletotrichum graminicola (Ces.) G.W. Wils., causes
stalk rot problems and contributes to increased lodging in New York and throughout many U.S.
maize-producing areas. The only economically feasible control of ASR is through resistant
varieties and cultural practices that reduce disease incidence. Recent research has focused on
exotic sources for improved ASR resistance, given the limited resistance available in temperate
maize germplasm. This project aims to develop new maize inbreds with excellent resistance to
ASR (derived from the tropical germplasm sources used) and good agronomic quality, yield
potential, and temperate adaptation (derived from the proprietary temperate inbreds crossed to
the exotic populations).
General Objective:
To develop temperate-adapted inbreds with both anthracnose stalk rot resistance and good yield
potential from GEM germplasm.
Specific Objectives for Current Project Year:
1) Conduct stalk rot resistance and yield evaluations in experimental hybrids from the 75%
temperate:25% tropical GEM population CH05015:N1204.
2) Complete S2 by tester crosses from the 75% temperate:25% tropical GEM population
UR10001:N1702.
3) Select best S1 families from GEM NSS ASR Synthetic testcross evaluations and advance to
S2 under stalk rot inoculation and selection.
4) Release Cycle 0 of the new population formed from the best non-stiff stalk inbreds derived
from GEM work to date (GEM NSS ASR Synthetic) as a new stalk rot resistant source
population.
Materials and Methods:
The procedures described herein represent a brief past history and the current year’s activities in
what are multi-year inbred development projects. In 2005, we began selfing and testcrossing in
two GEM populations (CH05015:N1204 and UR10001:N1702) that performed well in our
original anthracnose evaluation and have proven useful for other traits (CH05015 has shown
promise for yield potential and aflatoxin resistance; UR10001 has shown promise for yield
potential and corn borer resistance). Also in 2005, we initiated a population from the best nonstiff stalk inbreds identified through our project (seven inbreds from three GEM populations:
AR01151:N0406, FS8B(T):N1802, and GOQUEEN:N1603) by making all possible crosses
among these inbreds and then random mating for two generations. We have designated this
1
population GEM NSS ASR Synthetic. Our current year’s objectives are designed to move each
of these breeding populations forward.
Objective 1:
From the 75% temperate:25% tropical GEM population CH05015:N1204, 150 seeds were sown
at high density (about 40,000 plants/acre) in 2005 and individual plants with good nick and
reasonable flowering date were self pollinated to generate S1 families. In 2006, 44 S1 families
from CH05015:N1204 were grown in two separate blocks. In one block, per se ASR rating and
selfing were done on families with reasonable agronomic performance. In the second block,
testcrosses were made to an ASR-susceptible tester (B37) for ASR evaluations and to an elite
tester (LH198) for yield trials. Progenies of S1 by tester crosses from CH05015:N1204 were
evaluated in two replications for ASR resistance in Aurora NY (B37 tester) and in three
replications at two NY locations for yield potential (LH198 tester) in summer 2007. A rank sum
index was used to select the top performing families for both ASR resistance and yield. The S2
ears from selected families were planted out ear-to-row and crossed to B37 for future ASR
evaluation and to LH198 for future yield testing, with initial S2 testcrosses from the
CH05015:N1204 population made in 2008 and missing crosses completed in 2009. In 2010, we
evaluated this next set of testcrosses for yield (LH198 tester) in three-replication trials at two NY
locations and for stalk rot resistance (B37 tester) in two replications at Aurora, NY. The best
families for yield and stalk rot resistance will be selected for advancement.
Objective 2:
Inbred development from the UR10001:N1702 population has paralleled that described above.
In 2006, 60 S1 families from UR10001:N1702 were grown in two separate blocks. In one block,
per se ASR rating and selfing were done on families with reasonable agronomic performance. In
the second block, testcrosses were made to B37 for ASR evaluations and to LH198 for yield
trials. Progenies of S1 by tester crosses were evaluated in two replications for ASR resistance in
Aurora NY (B37 tester) and in three replications at two NY locations for yield potential (LH198
tester) in summer 2008. A rank sum index was used to select the top performing families for
both ASR resistance and yield. The S2 ears from selected families were planted out ear-to-row
and crossed to B37 for future ASR evaluation and to LH198 for future yield testing in 2009.
Missing testcrosses were completed in 2010.
Objective 3:
Population development for the GEM NSS ASR Synthetic was initiated from the best new nonstiff stalk inbreds developed in our previous GEM breeding effort by making all possible F1
crosses among seven GEM-derived inbreds from three different GEM populations [five from
FS8B(T):N1802 and two each from AR01150:N0406 and GOQUEEN:N1603]. The resulting
F1s were random mated in winter 2005-2006 and again in summer 2006 to constitute the original
cycle (Cycle 0) of this population. Inbreeding and stalk rot resistance selection was initiated in
GEM NSS ASR Synthetic by selfing in winter 2006-2007 to generate 115 S1 families. These
S1s were evaluated for ASR resistance in single row, unreplicated plots in 2007, and
simultaneously testcrossed to B37 (for stalk rot evaluation) and LH198 (for yield evaluation).
Based on per se stalk rot evaluations, 27 S1 families were selected. Testcrosses involving these
families that were missed in summer 2007 were completed in 2008, to generate a complete set of
S1s crossed to B37 and LH198. In 2009, B37 testcrosses of these S1s were grown for stalk rot
2
evaluations in two replications at Aurora, NY. Yield evaluations were done in three-replication
trials at two NY locations (Kingston and Pittsford) for the LH198 testcrosses. A rank sum index
was used to select the eight families with the best combined yield and stalk rot resistance. These
families were grown out ear-to-row in 2010, self pollinated (eight per family), and inoculated
with anthracnose stalk rot. At harvest, stalks were split and S2 ears from the most resistant
plants were kept for future testcrossing and evaluation.
Objective 4:
In 2009 and 2010, we increased seed of Cycle 0 of the GEM NSS ASR Synthetic by chain
sibbing among 200 plants. Trait values for numerous descriptive traits were assessed, including
stalk rot rating in comparison to known resistant and susceptible check inbreds, in preparation
for release as a source population. In 2010 we are preparing a manuscript for the Journal of Crop
Registrations describing this population to accompany its release.
Progress to Date:
Objective 1:
Inbreeding and selection for ASR resistance and yield potential in CH05015:N1204 was initiated
in summer 2007. From the 44 S1 families evaluated from this population, 26 were selected as
having good ASR resistance. Testcrosses to B37 from 23 of these S1s had sufficient seed for
ASR evaluation in summer 2007 (two replications at Aurora NY). Testcrosses to LH198 from
25 of the 26 S1s had sufficient seed for yield evaluations in summer 2007. Eight families were
selected based on their rank sum for yield and ASR resistance, and one additional family (for
which seed supply was inadequate to test for yield) was kept based on its ASR resistance alone.
The 35 S2 ears from plants with the best ASR resistance in these nine S1 families were planted
out ear-to-row in summer 2008 and crossed to B37 for ASR evaluation and LH198 for yield
evaluation, with missing testcrosses completed in summer 2009. B37 testcrosses were planted in
two replications in Aurora NY in summer 2010, inoculated with ASR shortly after flowering,
and stalks have recently been split and rated. Stalk rot resistance data will be analyzed and
summarized in the coming weeks. LH198 testcrosses were yield tested at Kingston and Pittsford
NY, with three replications at each location. Plots at both locations looked good this year.
Harvest is complete and yield data will be analyzed and summarized over the coming weeks.
Objective 2:
Inbreeding and selection for ASR resistance and yield potential in UR10001:N1702 was begun
in summer 2008. From the 60 S1 families evaluated, 29 were selected for ASR resistance.
Testcrosses to B37 from 22 of these had sufficient seed for ASR evaluation (two replications at
Aurora NY), and testcrosses to LH198 from 27 of them had sufficient seed for yield evaluations
(Kingston and Pittsford, NY). These evaluations were completed in summer 2008. A few
entries were lost at Kingston due to poor stand establishment (a problem specific to the Kingston
location in that year). Seven S1 families were selected based on the rank sum for testcross yield
and ASR resistance, two based on rank for ASR resistance alone (there was insufficient seed to
yield test them), and one additional family based only on rank sums for yield and maturity (B37
testcross seed was not available for ASR evaluation). All 40 S2 ears from these ten families
were planted out ear-to-row in summer 2009. A number of the S2s from this population showed
3
undesirable agronomic traits, including buggywhip or snarled whorl, smut, a tendency to snap at
the ear, and various forms of leaf burn. Eight families were eliminated in 2009 for these
problems. The rest were crossed to B37 for ASR evaluation and to LH198 for yield evaluation.
In summer 2010, we aimed to complete missing testcrosses and produce more seed of a few that
were in short supply. Seed has been harvested and is ready for shelling and processing to go into
2011 evaluations.
Objective 3:
In 2005, all possible crosses were made among the lines chosen to contribute to the GEM NSS
ASR Synthetic. The goal of this effort is to allow recombination among a diverse group of the
most promising non-stiff stalk inbreds derived from our GEM work to date, and then be able to
extract a new set of inbreds with excellent stalk rot resistance and improved yield potential and
standability. The lines included in this new synthetic are FS8B(T):N1802-derived inbreds
NY212 and NY215 and unreleased lines 222, 259, and 263 from this same population;
AR01150:N0406-derived inbred NY266 and unreleased line 218; and GOQUEEN:N1603derived lines 233 and 239 (both unreleased at present). Two generations of random mating were
done in this material and then 115 S1 families generated in winter 2006-2007. These S1s were
evaluated for ASR resistance in single row, unreplicated plots in Aurora 2007, and
simultaneously testcrossed to B37 (for ASR evaluation) and LH198 (for yield evaluation).
Based on per se ASR resistance, 28 families were selected for advance to testcross evaluations.
Most missing testcrosses were completed in 2008 and evaluations for ASR and yield done in
2009. ASR resistance ratings and yield data for these families are presented in Table 1. Seven
families were selected based on rank sums for yield and ASR resistance in testcross
combinations, and one based on its rank for ASR resistance only (there was insufficient seed to
yield test this family). Selected families are shaded gray in Table 1. These eight S1 families
were planted out ear-to-row in summer 2010, self pollinated, inoculated with ASR, and rated by
splitting stalks at harvest. S2 ears from the most resistant plants in each family were kept for
2011 testcrossing.
Objective 4:
Seed increase and characterization data were collected for release of Cycle 0 of the GEM NSS
ASR Synthetic in 2009 and 2010. This year’s stalk rot resistance and descriptive data needs to
be summarized. Once data summarization is complete and a germination test has been done on
the seed, this population will be ready for release as a broadly-based non-stiff stalk source of
anthracnose stalk rot resistance. A germplasm release manuscript is in preparation.
Summary of Accomplishments:
Selection and inbreeding has been initiated in one new GEM-derived synthetic population and
two new GEM populations to begin producing new ASR resistant inbreds from this project. A
first generation of yield and stalk rot resistance evaluation in parallel sets of testcrosses was
completed in 2007 on S1 families from CH05015:N1204, in 2008 on S1 families from
UR10001:N1702, and in 2009 on S1 families from the new GEM NSS ASR Synthetic. Second
cycle testcrosses from CH05015:N1204 were similarly evaluated in 2010, testcross seed is ready
to evaluate those from the UR10001:N1702 in 2011, and we are developing such seed for GEM
NSS ASR. The original cycle of GEM NSS ASR is ready for release as a source population. All
populations will continue to be advanced, pending adequate funding.
4
Table 1. Results from evaluation of S1 families from GEM NSS ASR Synthetic in summer 2009
for ASR resistance (B37 testcrosses, two reps, Aurora NY) and yield (LH198 testcrosses, three
reps, Kingston and Pittsford NY), and rank sum data. Selected families are shaded in gray.
9574
Entry
No.
ASR Rating (%)
Inter- Internodes 2-8
node
Mean Maxi1
Means from Kingston and Pittsford
Grain
Mois- Yield/ Stalk
Root
ture
Mois. Lodge Lodge
Yield
(%)
Ratio
(%)
(%)
(bu/A)
27
65.3
7.3
14.2
174
23.7
7.3
12
48.6
6.3
17.4
168
25.8
6.7
6
72.9 10.7 23.3
174
25.5
7.0
26
69.0 13.5 28.0
183
25.5
7.3
16
59.9 12.8 24.2
176
25.6
7.0
18
64.4
6.5
17.5
157
25.0
6.4
4
59.8 11.2 20.7
171
26.4
6.6
25
69.0 14.3 30.3
154
24.6
6.5
20
59.8 10.8 22.9
167
27.7
6.1
19
75.2 19.6 38.1
184
25.6
7.3
11
59.8 17.7 28.0
180
26.0
7.0
15
73.6
8.5
27.2
141
26.0
5.5
14
66.7 16.4 30.6
166
26.1
6.6
9
66.7 14.7 40.5
160
26.3
6.3
1
64.4 14.7 40.4
151
25.7
6.0
22
62.1 11.4 29.9
132
26.5
5.0
8
59.8 20.5 39.7
171
26.9
6.5
17
65.2 14.9 31.1
159
27.5
5.8
13
57.4 16.2 33.0
140
25.3
5.7
5
62.2 15.2 30.5
140
26.4
5.3
2
62.2 23.7 37.5
160
26.1
6.3
7
74.4 19.5 32.7
154
26.2
5.9
23
77.5 24.2 51.3
164
26.6
6.3
10
70.6 22.1 42.1
159
26.1
6.2
3
71.3 15.3 28.4
157‡ 28.4‡ 5.6‡
21
63.6 17.2 31.7
131‡ 28.0‡ 4.7‡
24
73.8 21.9 36.9
189‡ 26.4‡ 7.2‡
31
73.6
3.6
9.4
*
*
*
* Insufficient testcross seed available for evaluation.
‡ Yield data from Pittsford location only.
5
3
0
3
7
4
2
2
2
2
1
3
1
2
2
3
10
2
2
5
9
4
4
5
3
2‡
4‡
1‡
*
3
0
2
1
0
0
2
1
0
0
0
2
0
0
1
2
1
0
0
6
1
7
4
0
0‡
0‡
0‡
*
ASR
Rating
Rank
Sum
Yield/
Mois.
Rank
Sum
Total
Sum
of
Ranks
4
2
6
11
10
3
8
12
7
23
21
5
19
13.5
13.5
9
24
15
18
16
27
22
28
26
17
20
25
1
2
7
5
2
5
12
8.5
10.5
17
2
5
22
8.5
14
18
24
10.5
20
21
23
14
19
14
16
‡
‡
‡
*
6
9
11
13
15
15
16.5
22.5
24
25
26
27
27.5
27.5
31.5
33
34.5
35
39
39
41
41
42
42
‡
‡
‡
*