Close-up of the ears of the TB2018 wheat variety near Lecce, Italy. Credit: Salvatore Colecchia.
A variety of durum wheat has been discovered in Southern Italy by a group of researchers led by Fernando Tateo, a food chemist at the University of Milan.
After studying it, the researchers concluded that the wheat is related to the renowned Senatore Cappelli, a variety obtained in 1915 and widely used in Italy until the 1960s, when it was replaced by more productive ones. The new variety, labelled TB2018, probably derived spontaneously from the old one, but developed some traits that could make it more productive1.
“I noted a bunch of durum wheat ears in an abandoned field in the Lecce province” explains Tateo, “their grains resembled those of Senatore Cappelli, but the stems were shorter”. Reduced height is a desired feature because it prevents the stems from bending over to ground level, thus facilitating harvesting and reducing the risk of contamination.
The authors grew TB2018 in controlled conditions for two years, measuring an average stem height of 110 centimeters, lower than Senatore Cappelli’s average of 135cm. Both the morphological analyses and the analysis of soluble proteins extracted from flour made from TB2018 confirmed the similarity to Senatore Cappelli. On the other hand, the roots emerging from the seeds in the early stages of growth were shorter than those of Senatore Cappelli. Longer roots allows rapid exploration of deep soil, optimizing nitrogen and water uptake.
“To study the TB2018’s genome, we decided to re-sequence it, rather than using methods based on molecular markers which explore only specific positions in it”, explains Filippo Geuna, a geneticist at the University of Milan, who led this part of the study. Re-sequencing is possible when a reference genome for the species is available and allows the identification of genetic variations with respect to the reference one. For durum wheat, the reference genome is the one of the Svevo variety, sequenced for the first time in 2019.
Re-sequencing the new variety allowed a look at associations between genes and physiological features. For example, the authors identified a mutation in a regulatory gene that could be responsible for plant or root elongation. “Re-sequencing also allowed us to compare TB2018 with a set of 259 varieties that were genetically characterized in previous works and confirm the genetic proximity to Senatore Cappelli”, Geuna adds.
Durum wheat breeding programs started in Italy in the early 1900s and intensified after World War II, leading to a reduction of genetic diversity of this cereal. In recent years, climate change has led to a new interest in local varieties as a source of genetic inspiration for durum wheat breeders.
