Biodiversity Data Journal :
General research article
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Corresponding author:
Academic editor: Lyubomir Penev
Received: 20 Feb 2015 | Accepted: 11 Aug 2015 | Published: 14 Aug 2015
© 2015 Paolo Laino, Margherita Limonta, Davide Gerna, Patrizia Vaccino
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Laino P, Limonta M, Gerna D, Vaccino P (2015) Morpho-physiolological and qualitative traits of a bread wheat collection spanning a century of breeding in Italy. Biodiversity Data Journal 3: e4760. https://doi.org/10.3897/BDJ.3.e4760
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Evaluation and characterization are crucial steps in the exploitation of germplasm collections. The Sant’Angelo Lodigiano unit of the Consiglio per la ricerca in agricoltura e l’analisi dell’economia agraria (CREA) maintains a broad collection of Triticum spp, including more than 4000 genotypes of T. aestivum. Such collection represents a wide source of genetic variability for many agronomic and qualitative traits, extremely useful in modern breeding programs. The collection size, however, makes very difficult its management as a whole. A reduced subset, representing the process of wheat breeding in Italy during the last hundred years, was hence identified for an in-depth characterization. The lines were cropped in two locations over two growing seasons, and analyzed using 16 morpho-agronomic and qualitative descriptors. Most of the analysed characters showed a broad variation throughout the collection, allowing to follow the plant ideotype changes across the breeding progress in Italy during the 20th century.
Triticum aestivum; phenotyping; genetic resources; Italy; wheat breeding
Wheat is one of the most important crop worldwide, occupying 17 percent of the total cultivated land in the world and providing the staple food for 35 percent of the world’s population (http://www.idrc.ca/EN/Resources/Publications/Pages/ArticleDetails.aspx?PublicationID=565). In Italy, during 2013, wheat was cultivated on approximately 1.9 million hectares, 632,000 of which devoted to bread wheat, the remaining to durum (ISTAT 2013).
Although wheat breeding started some years later in Italy than in other European countries such as Germany, France and Sweden, a great effort was soon dedicated to it. As far as bread wheat is concerned, at the beginning of the 20th century its cultivation in Italy relied mainly on landraces (Gentil Rosso, Cologna, Rieti, Solina) and some French genotypes (i.e. Inallettabile); breeding consisted only in the selection of their best variants. Nazareno Strampelli (1866-1942), rightly considered the pioneer of wheat breeding in Italy, started his remarkable career by selecting the best genotypes from the rust-resistant wheat landrace “Rieti”. Nevertheless, despite his early success, he quickly realized that it was difficult to obtain significant improvement by selecting only within population. Unaware of Mendel’s laws of inheritance (rediscovered only in 1900 by De Vries, Correns and Von Tschermak), he started a deliberate crossing program involving Italian and foreign varieties (
Once the superiority of hybridization over within-population selection was established, wheat breeding was carried on using hybridization. This led to the constitution of several important cultivars. In the 50s and 60s cvs S. Pastore, Autonomia, Mara and Funo dominated the seed market, S. Pastore being the most widespread cultivar until mid-70s. The 70s saw Marzotto and Irnerio taking the leading positions, while in the next decade Centauro, Pandas and Mec got the leadership of the market. Centauro, in particular, was the most diffused cultivar until 2000, when it was displaced by Serio. Serio, together with Bolero and Mieti, had an outstanding spread until the half of the first decade of the 21st century, when a quicker turnover, mainly based on foreign varieties, started to be observed. Nowadays the six most cultivated varieties (Bologna, Aubusson, Blasco, PR22R58, Altamira and Solehio) cover more than 30% of the total area, according to estimates based on the distribution of certified seed, which represent more than 90% of the seed annually sold in Italy.
CREA-SCV maintains a collection of Triticum sspp. including more than 4000 genotypes of T. aestivum. Such collection represents a wide source of genetic variability for many agronomic and qualitative traits, extremely useful in modern breeding programs. Thanks to the funding of the project RGV-FAO (started in 2004 in order to implement the FAO International Treaty on Plant Genetic Resources for Food and Agriculture) financed by the Italian Ministry of Agriculture (MIPAAF), the collection is maintained, catalogued and characterized by passport and specific descriptors, such as pedigree, country of origin, plant height, glume and seed colour, etc. The huge size of the collection, however, makes very difficult its management as a whole; as a consequence, we decided to focus on a reduced subset made of 226 accessions representing the bread wheat breeding process in Italy during the last hundred years. The evaluation of the genetic variation of such collection for several morpho-physiological and qualitative traits is the objective of the present study.
Two hundred and twenty six bread wheat varieties representative of wheat breeding in Italy from the beginning of XX century up to the present, were selected from the germplasm bank of CREA-SCV. The complete list of the accessions tested, with their pedigree, year of release/registration and collection code is presented in Suppl. material
Mean, minimum and maximum values and standard deviations for nine continuously variable descriptors measured on the bread wheat accessions under study. The reported data are the average values from two locations (SAL and LO) and two growing seasons (2011-12 and 2012-13).
Descriptor |
Code |
Mean |
Minimum |
Maximum |
Standard deviation |
Heading date (days from 1st April) |
HD |
37.0 |
24.8 |
55.0 |
5.99 |
Plant height excluding awns (cm) |
PH |
103.8 |
58.0 |
153.5 |
27.29 |
Spike length (cm) |
SL |
10.0 |
6.5 |
16.0 |
2.08 |
Spikelets/spike (n°) |
Sp/S |
19.0 |
15.0 |
23.8 |
1.46 |
Seeds/spike (n°) |
Se/S |
49.2 |
30.5 |
66.9 |
7.59 |
Seed length (mm) |
SeL |
7.1 |
6.0 |
9.9 |
0.52 |
1000-kernel weight (g) |
TKW |
43.0 |
27.1 |
67.5 |
5.89 |
Protein content (% dm) |
PC |
14.1 |
11.3 |
17.4 |
1.30 |
SDS sedimentation volume (mL) |
SSV |
39.9 |
17.5 |
61.7 |
7.85 |
Specific SDS sedimentation volume |
sSSV |
2.9 |
1.2 |
4.3 |
0.60 |
Frequency distribution (%) for the discontinuously variable descriptors measured on the bread wheat accessions under study. The reported data are the average values from two locations (SAL and LO) and two growing seasons (2011-12 and 2012-13).
Descriptor |
Code |
Class |
1 |
2 |
3 |
4 |
Growth habit, juvenile |
GH |
1. Erect 2. Semi-erect 3. Prostrate |
62.0 |
31.0 |
6.9 |
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Spike shape |
SS |
1. Fusiform 2. Clavate 3. Oblong |
26.5 |
9.6 |
63.8 |
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Spike density* |
SD |
1. Very lax (<16) 2. Lax (16-25) 3. Intermediate (26-30) 4. Dense (31-40) |
18.5 |
70.3 |
10.4 |
0.8 |
Awnedness |
AW |
1. None or <10 mm long awns 2. 10-40 mm long awns 3. Awns longer than 40 mm 4. Awns longer than spike |
41.6 |
4.2 |
48.2 |
5.9 |
Glume colour |
GC |
1. Red to brown 2. White/amber |
25.5 |
74.5 |
||
Seed colour |
SeC |
1. Red to brown 2. White/amber |
83.4 |
16.6 |
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Kernel hardness |
Ha |
1. Soft 2. Medium 3. Hard |
50.4 |
40.7 |
8.9 |
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*n° spikelets per 10 cm length of spike |
The data obtained by the morpho-physiological and qualitative analyses are reported in Suppl. material
Mean, minimum and maximum values and standard deviations for nine continuously variable descriptors are reported in Table
Radar chart of the average heading date (A) and plant height (B) of the lines under study across two locations (SAL and LO) and two growing seasons (2011-12 and 2012-13). The data behind the graphs are reported in Suppl. material
Radar chart of the average spike lenght (A) and seed lenght (B) of the lines under study across two locations (SAL and LO) and two growing seasons (2011-12 and 2012-13). The data behind the graphs are reported in Suppl. material
Radar chart of the average thousand kernel weight (A) and specific sedimentation volume (B) of the lines under study across two locations (SAL and LO) and two growing seasons (2011-12 and 2012-13). The data behind the graphs are reported in Suppl. material
As far as the spike is concerned, the most common shape was oblong, present in 63.8% of the lines, followed by fusiform (26.5%), while only 9.6% of the lines were clavate (Table
The correlations among some analysed variables are reported in Table
Correlations among traits measured on the bread wheat accessions under study.
HD |
PH |
SL |
Sp/S |
Se/S |
SeL |
TKW |
PC |
SSV |
|
PH |
0.68** |
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SL |
0.69** |
0.73** |
|||||||
Sp/S |
0.33** |
0.11 |
0.40** |
||||||
Se/S |
-0.30** |
-0.51** |
-0.26** |
0.40** |
|||||
SeL |
0.37** |
0.59** |
0.50** |
-0.12 |
-0.56** |
||||
TKW |
0.28** |
0.56** |
0.44** |
-0.07 |
-0.52** |
0.75** |
|||
PC |
0.51** |
0.67** |
0.52** |
-0.02 |
-0.46** |
0.43** |
0.29** |
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SSV |
-0.11 |
-0.24** |
0.03 |
0.06 |
-0.05 |
-0.10 |
-0.07 |
0.07 |
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sSSV |
-0.31** |
-0.51** |
-0.19** |
0.07 |
0.15* |
-0.27** |
-0.19** |
-0.37** |
0.90** |
Level of statistical significance: * P<0.05; ** P<0.01 |
A broad variation for several morpho-physiological and qualitative traits was observed in the bread wheat collection under study, allowing to follow the plant ideotype changing across the breeding progress in Italy during the 20th century.
A strong reduction of plant height was achieved as early as 1914, with the first cultivars released by Nazareno Strampelli. Plant size reduction was mainly achieved by using the short-straw bread wheat Japanese variety Akakomugi, adopted by Nazareno Strampelli in his very first crosses. Strampelli obtained a free sample of seeds in 1911 from the Ingegnoli company in Milan and soon realised it had no agronomic value (
The spike, over time, became shorter and denser, with more and smaller seeds. All over continental Europe, in the late 19th and early 20th century, the density of the spike was improved by crossing local winter wheat landraces with square head wheats from England (
In our collection, the prostrate growth habit of young plants was far less common than the erect growth habit, and was spotted only in the landrace Solina and in two selections from the landrace Inallettabile. The same situation is reported by
The majority of the genotypes had red seeds. White wheat usually shows a higher tendency than red wheat to pre-harvest sprouting (
As far as the “bread making” quality is concerned, a reduction of the protein content (one of its key factors) was observed going from the landraces to the more recent cultivars. Nevertheless, the quality progressively increased over time, as shown by the increase of the SDS sedimentation volume and of the specific SDS sedimentation volume. Protein content alone, in fact, does not necessarily lead to good bread making quality. In fact, this trait is strongly affected by the allelic composition of the endosperm storage proteins (gliadins and glutenins), which largely influence strength and elasticity of the dough. In particular, by the middle of the 80s, the results of extensive genetic and biochemical studies clearly demonstrated that differences in the number and type of HMW glutenin subunits strongly affect the breadmaking properties through effects on the amount and size distribution of glutenin polymers. More recently, the contribution of LMW glutenin subunits both per se and for their interactions with HMW through additive and epistatic effects became also evident (a thorough dissertation on gluten proteins and their role in breadmaking is present in
Along with quality improvement, a sharp increase in kernel hardness can be observed among the cultivars released since 1970, which show values typical of medium and hard classes. Nevertheless, such trend cannot be ascribed to a precise breeders’ intent, but is a by-product of the selection for high breadmaking quality. In fact wheats with higher kernel texture, although requiring more energy and time for milling, produce flours with optimal technological characteristics for the production of bread and leavened baked products (
The significant positive correlation of heading date with plant height clearly derived from the close linkage between Rht8 and Ppd-D1 gene above discussed. On the other end, most of the significant correlations are probably linked to the germplasm composition: the oldest varieties are taller than the most recent ones, and have longer but lax spikes which bear less seeds per spike. As a consequence, the photosynthates accumulation leads to bigger, heavier seeds. Additionally, the oldest varieties have higher protein content but show lower bread making quality, in term of sedimentation volume: hence the significant negative correlation with the specific sedimentation volume.
Research carried out within the project “Implementation of the FAO International Treaty on Plant Genetic Resources for Food and Agriculture” of the Ministry of Agriculture, Alimentation and Forestry Policies, aimed at research and experimentation supporting the collection, characterization and evaluation of plant genetic resources. Publication no. 277.
P. Vaccino planned and coordinated the work and wrote the manuscript text; P. Laino, D. Gerna and M. Limonta performed the data collection and carried out the statistical analyses.