ASSESSMENT OF GENETIC VARIATION IN BREAD AND DURUM WHEAT VARIETIES USING SSR MARKERS TO ENSURE VARIETAL IDENTITY
Author(s)
Date Issued
2024
Type
conferenceObject
Abstract
Wheat is one of the most important cereal crops in the world and is used to
make a variety of products, including bread, pasta and many others, both
leavened and non-leavened. In Italy, the presence of monovarietal products
on the food market requires accurate varietal traceability to verify seed
purity, which is essential for maintaining high quality standards and
guaranteeing consumers. Genetic purity is traditionally assessed based on
morphological and bio-agronomical traits, but these approaches are highly
sensitive to environmental effects. Alternatively, molecular markers
represent a suitable tool to overcome the drawbacks of morphological and
biochemical markers. Microsatellites or Simple Sequence Repeats (SSRs),
exhibiting multiallelic variation, reproducibility, codominance, relative
abundance and good genome coverage are extensively employed in genetic
fingerprinting. A representative SSR alleles database for wheat varieties
would greatly simplify the protocol for verifying varietal identity, also
resolving cases of homonymy and synonymy among the commercialized
varieties, as well as improving the management of genetic resources. The
present study analysed SSR polymorphisms in 60 bread (T. aestivum L.) and
durum (T. durum Desf.) wheat varieties, including old and new varieties,
some of these marketed as "conservation varieties", to assess their
effectiveness in varietal distinction and genetic purity determination.
Molecular analysis was performed using a set of eight SSR primers
recommended by the International Union for the Protection of New Varieties
of Plants (UPOV). The number of alleles (Na), Effective number of alleles
(Ne), Shannon index (I), Observed heterozygosity (h), were calculated using
GenAlEx 6.5 software. A total of 60 alleles, 4 of which were present only
in bread wheat on the D genome, were detected with an average of 7.5
alleles per locus and a Ne value of 1,35. The polymorphism information
content (PIC) of each SSR marker ranged from 0.44 to 0.84 with a mean of
0.72, confirming the discriminatory power of selected markers. Molecular
data were also used to obtain Nei’s genetic distance and a dendrogram that
showed two distinct clusters including durum and bread wheat, respectively,
as also confirmed by Principal Coordinate Analysis (PCoA). Among the two
Triticum species considered, T. aestivum L. had the highest number of total
alleles (45 vs. 43) and a mean Shannon index of 0,37, ranging from 0,14 to
0,69. Moreover, molecular variance analysis (AMOVA) revealed 79%
intraspecific and 21% interspecific variation, attributed to private
alleles detected: 14 in durum and 16 in bread wheat. In conclusion, the
eight molecular markers allowed unique identification of each sample,
highlighting similarities and differences among samples, supporting the
effectiveness of SSR markers to perform a varietal high throughout
fingerprinting for wheat varieties, traceability and variety identification.
Conference(s)
LXVII SIGA Annual Congress