Phenotypic Characterization of a Diversity Panel of Tomato
Larry D. Robertson, Teri Balch, Susan M. Sheffer, and Joanne A. Labate
UDSA-ARS, Plant Genetic Resources Unit, Geneva, NY 14456
Methods
Plant Materials
45
40
35
Rosa o Monserrat
Zhongza No. 4
Tomate del Lugar
Pomodoro Superselezione di Marmande
AVRDC #6
Flora-dade
"Cherry"
Rinon
Tomate
Merville des Marches
Sao Paulo
Rinon
Abel
na
na
Rumi Banjan
na
Ccoilo-Chuma
na
na
na
na
na
na
na
na
Prospero
Chih-Mu-Tao-Se
na
Vetomold (121 Mass.)
na
Turrialba
na
na
Ailsa Craig
Cotaxtla I
Ponderosa
na
na
na
Kiyosu No. 2
Hong Kong
Devon Surprise
Heinz 1370
na
Chilcarojo
A-1770
A-1771
1091-Chonto 21 (Mataverde) (3-21-2)
Peto 460
Lycopene, Vitamin C, and obrix were recorded for
the 50 tomato accessions in this diversity panel.
Relationships among these traits are shown in
Fig. 11. The accession with the highest Vitamin C
(14.5 ug/ml) and highest lycopene (13.0 ug/g) was
PI 212062 (Fig. 12). There was a very high
correlation between lycopene and vitamin C
(r=0.94**, df=48). The correlation of oBrix and
Vitamin C was also significant (r=0.38*, df=48).
25
25
20
°Brix:
Brix degree data, refractive index at 20°C (Carli et al., 2009), were collected using a Model
DR103L digital refractometer (QA Supplies). Juice from randomly selected cut fruit pieces
was squeezed onto the refractometer. For each sample the °brix was calculated as a mean of
3 readings of separate fruit within each accession. °Brix is a measure of the soluble sugar
content including glucose and fructose in ratios of approximately 1:1 to 1:1.5. Brix degree is
considered a measurement of fruit sweetness; high °brix equates to higher sweetness.
15
10
20
5
0
Red
Orange
Gold
Pink
15
Figure 7. Fruit color for 50 tomato accessions
Brix degree
Lycopene:
Fruit pieces were homogenized in a commercial grade Waring blender (one to ten fruits per
accession). An aliquot of homogenate was transferred to a 5 cm petri dish, and readings
were taken using a Minolta Chroma Meter CR-300 by pointing the sensor close to the
homogenate surface. Values were recorded for L*a*b* (also referred to as CIELAB) color
space. L* indicates lightness, a* (red-green) and b* (blue-yellow) are chromaticity
coordinates (http://en.wikipedia.org/wiki/Lab_color_space). Each L*a*b* value represented
the average of three measurements. Lycopene was estimated using a regression model
based on the transformed a*4 value (Hyman et al. 2004).
Vit C (ug/ml)
25
20
5
0
10
PI 125831…
PI 157993
PI 159198
PI 258474
PI 647566
PI 196297
PI 127820
PI 390510
PI 270206
PI 262995
PI 117563
PI 124035
PI 159009
PI 258478
PI 129084
PI 129128
PI 129033
PI 647305
PI 647486
PI 158760
PI 270408
PI 125831…
PI 121662
PI 129026
PI 128586
PI 129142
PI 99782
PI 128592
PI 647447
PI 406952
PI 294638
PI 270430
PI 109834
PI 118783
PI 124037
PI 505317
PI 452026
PI 268107
PI 98097
PI 98097…
PI 452027
PI 647445
PI 341134
PI 281555
PI 272703
PI 97538…
PI 97538
PI 600920
PI 155372
PI 127825
PI 291337
PI 647556
PI 212062
15
Vitamin C:
Fruit pieces were homogenized in a commercial grade Waring blender (one to ten fruits per
accession). A 100 ul aliquot of homogenate was pipetted into a 1.5 ml eppendorf tube, 500
ul of 6% metaphosphoric acid was added and the tube was vortexed. Samples were
centrifuged at 15K rpm for 10’ at 4°C, 100 ul of clear supernatant was transferred to a 1.5 ml
tube containing 100 ul of 5% metaphosphoric acid. Samples were then assayed using a
Cosmo Bio Co. Ltd. (Japan) Vitamin C assay kit (Prod. No. SML-ROIKO2-EX) according to the
kit protocol. Vitamin C was estimated based on absorbance at 530 nm using a standard
curve of known concentrations.
Figure 11. Brix content, Lycopene, and Vitamin C for 50 tomato
accessions, sorted by Vitamin C
0
slight flat
flat
pear
plum
heart
globe
blocky
Figure 8. Fruit shape for 50 tomato accessions
25
Summary
20
15
General Observations
These accessions exhibited many traits not
seen in modern cultivars of tomato. Variation
in foliage color was observed (Fig. 2). Modern
tomato has non-exserted stigmas (Fig. 3).
However, many of these accessions expressed
exserted stigmas (Fig. 4). Several accessions
expressed floral
abnormalities, with multiple
ovules (Fig. 5), which resulted
in multiple fused fruit with a
spherical, fasciated shape
Figure 2. Variation of
foliage color in tomato
(Fig. 6).
Lycopene (ug/g)
10
Frequency
Name
Nutritional Traits
30
10
5
0
3
4
5
6
7
Figure 9. Fruit uniformity for 50 tomato accessions; 1=no
uniformity, 9=completely uniformity.
This diversity panel of 50 PGRU tomato accessions
represents only a small fraction of the available diversity
preserved in the National Plant Germplasm System. There
was a large variation expressed for all traits. Fruit size, color,
shape and uniformity were as expected in landraces and
vintage cultivars. Variation in the nutritional traits is
potentially useful for crop improvement. PI 212062
was an outlier for both lycopene
and Vitamin C (Figs. 11 and 12).
This accession deserves further
investigation.
Fruit Size
Size of the fruit of this tomato diversity panel was
measured using average perimeter (cm) and average fruit
weight (g). Fruit weight ranged from 1.2 to 37.2 g and
perimeter ranged from 9.8 to 32.4 cm (Fig. 10). Fruit
weight and perimeter of fruit were highly correlated
(r=0.93**, df=48).
landraces
Figure 12. PI 212062
Literature Cited
Carli, P, Arima S, Fogliano V, Tardella L, Frusciante L, Ercolano MR (2009). Use of network analysis to
capture key traits affecting tomato organoleptic quality. Journal of Experimental Botany 60: 3379–
3386.
Gonzalo T., M.J. Brewer, M.T., Anderson, C., Sullivan, D., Gray, S., van der Knaap, E (2009). Tomato
fruit shape analysis using morphometric and morphology attributes implemented in tomato analyzer
software program. J. Am. Soc. of Hort. Sci. 134: 77-87.
40
Hyman J.R., J. Gaus, and M.R. Foolad (2004). A rapid and accurate method for estimating tomato
lycopene content by measuring chromaticity values of fruit puree. J Amer Soc Hort Sci 129:717-723.
35
30
Labate JA, Robertson LD, Baldo AM (2009). Multilocus sequence data reveal extensive departures
from equilibrium in domesticated tomato (Solanum lycopersicum L.). Heredity 103: 257-267.
25
20
Figure 3. Non-Exserted stigma
Figure 4. Exserted stigma
Mean Perimeter (cm)
15
Mean Fruit Weight (g)
Robertson LD, Labate JA (2007). Genetic resources of tomato (Lycopersicon esculentum Mill.) and
wild relatives. In: Razdan MK,Mattoo AK (eds). Genetic Improvement of Solanaceous Crops. Science
Publishers: Enfield, NH. Vol. 2: Tomato, pp 25–75.
10
5
0
PI 390510
PI 129084
PI 647556
PI 127820
PI 129142
PI 155372
PI 127825
PI 270408
PI 97538
PI 99782
PI 452027
PI 272703
PI 258478
PI 98097
PI 128586
PI 117563
PI 129128
PI 125831
PI 294638
PI 452026
PI 129033
PI 505317
PI 262995
PI 118783
PI 129026
PI 196297
PI 125831
PI 121662
PI 600920
PI 159198
PI 212062
PI 109834
PI 270430
PI 406952
PI 159009
PI 291337
PI 124035
PI 281555
PI 647447
PI 157993
PI 341134
PI 158760
PI 258474
PI 268107
PI 124037
PI 647486
PI 647445
PI 647566
PI 270206
PI 128592
Year
1905
1905
1989
1992
2001
2002
1905
1932
1932
1935
1936
1936
1937
1937
1937
1937
1938
1938
1938
1938
1938
1938
1938
1938
1938
1946
1947
1947
1947
1947
1951
1954
1959
1959
1960
1960
1960
1960
1960
1961
1962
1963
1964
1969
1974
1976
1980
1980
1986
2003
50
cm or g
Table 1. Tomato accessions used in this study
Country
Spain
China
Bolivia
Italy
Taiwan
United States
Argentina
Cuba
Peru
France
Brazil
Venezuela
Canada
Peru
Chile
Afghanistan
Bolivia
Peru
Chile
Chile
Ecuador
Ecuador
Colombia
Panama
Ecuador
Peru
Italy
China
Peru
United States
Nicarragua
Costa Rica
Ecuador
Peru
Netherlands
Mexico
United States
Mexico
Mexico
Guatemala
Japan
China
United Kingdom
United States
Ecuador
Nicarragua
Mexico
Mexico
Colombia
United States
Fruit shape, uniformity and color:
Fruit shape, uniformity and color were determined based on descriptors presented by the
Tomato Crop Germplasm Committee (CGC) (http://www.arsgrin.gov/npgs/descriptors/tomato). Fruit shape was determined via visual selection between
the following shapes: flat, slightly flattened, round, plum, blocky, pear, oblong, high round
and heart. Uniformity was based on a sliding scale of 1 through 9 with 1 indicating no
uniformity and 9 indicating very high uniformity. Color was determined using visual selection
of colors as presented by the Tomato CGC report (red, orange, yellow, gold, white and
green).
Fruit color, fruit shape and fruit uniformity
are shown in Figs. 7-9. Most accessions
were red fruited and most were slightly flat
to flat. Fruit uniformity was low, as
expected from less-improved populations.
5
The 50 diverse accessions of tomato grown in this study are listed in Table 1. These included a
landrace panel of 30 PGRU tomato accessions assembled based on results of RAPD analyses
including 14 accessions from the primary center of diversity and 12 accessions from countries
contiguous with the primary center previously reported (Labate et al., 2009). This set was
expanded by selection of additional accessions based on geography and time of collection or
date of cultivar release.
ID
G 29393
G 29883
G 29886
G 30627
G 32403
G 32414
PI 97538
PI 98097
PI 99782
PI 109834
PI 117563
PI 118783
PI 121662
PI 124035
PI 124037
PI 125831
PI 127820
PI 127825
PI 128586
PI 128592
PI 129026
PI 129033
PI 129084
PI 129128
PI 129142
PI 155372
PI 157993
PI 158760
PI 159009
PI 159198
PI 196297
PI 212062
PI 258474
PI 258478
PI 262995
PI 268107
PI 270206
PI 270408
PI 270430
PI 272703
PI 281555
PI 291337
PI 294638
PI 341134
PI 390510
PI 406952
PI 452026
PI 452027
PI 505317
PI 600920
Tomato Analyzer:
Tomato Analyzer is a software application which demonstrates objective quantitative
measurements of fruit shape, size and color (Gonzalo et al., 2009). Mid-height, longitudinal
dissections were made on each of 10 to 15 fruit per accession. The halves were placed on a
Microtek Scanmaker 9800XL 11” x 17” scanner bed and scanned with a black background at
300 dpi (pixels per inch). The images were saved as .jpg files and analyzed using Tomato
Analyzer 2.2.0.0, manual adjustments were made for boundary and proximal and distal end
shape. Mean perimeter and mean area were extrapolated from the data.
Frequency
Thousands of open-pollinated populations and
inbred lines of domesticated tomato (Solanum
lycopersicum L.) are conserved in germplasm centers
such as the USDA, ARS Plant Genetic Resources Unit
(PGRU) (Robertson and Labate, 2007). These
collections provide a publicly available resource for
experimentation and breeding to a broad
community of users around the world. Landrace
germplasm from the center of origin is expected to
have a higher diversity than modern cultivars. Such
germplasm can provide a source of novel alleles.
This study reports on
an evaluation of a set of
50 geographically
diverse PGRU
accessions (Fig. 1) for
fruit morphological
Figure 1. Fruit of 50 tomato
traits, size and
accessions evaluated for this study
nutritional traits.
Fruit Morphological Traits
Frequency
Background
Figure 10. Fruit weight (g) and perimeter (cm) for 50 tomato accessions,
sorted by fruit weight
Figure 5. Flowers of PI 258474
Figure 6. Fruits of PI 258474
Acknowledgements
We thank William Garman III, John Oughterson, Paul Kisly, and Jonathan Spencer for
excellent technical support. This study was funded by CRIS Project 1910-21000-01900D and the Tomato CGC.