Wheat is one of the oldest cultivated plants and one of the most important sources of food. Under this name, different species are included, two of which are the most commonly grown: Triticum aestivum, also known as bread wheat, because mostly used for bread and leavened products, and Triticum turgidum ssp. durum (also known as T. durum or durum wheat), mostly used for pasta or typical Mediterranean foods such as bulghur, couscous, and, in some cases, flat and leavened bread as well.

The genome composition of T. aestivum is AABBDD, namely, hexaploidy, whereas that of the tetraploid T. durum is AABB. Moreover, T. durum, other subspecies of T. turgidum, share the same genomic composition, among which there are T. turgidum ssp. polonicum and T. turgidum ssp. turanicum, also known, respectively, as T. polonicum (or Polish wheat) and T. turanicum (or Khorasan wheat, from the Iranian Region where it was first described). They are free-threshing with tough rachis that are easy-harvest wheats, because they have soft glumes and non-hulled seeds (Yang et al., 2022). T. turanicum and T. polonicum are closely related, and it has been suggested that the first originated from the hybridization with T. dicoccon (Michalcová et al., 2014).

The importance of the two subspecies has increased in the last decades, as a consequence of the introduction in the market of KAMUT^® brand wheat, an ancient variety of grain (Triticum turgidum ssp. turanicum) that has reached a high popularity because of its suggested positive effects on human health (Bordoni et al., 2017; Spisni et al., 2020). In the wake of KAMUT^® brand wheat, any Khorasan wheat is acquiring importance because it is considered healthy (Geisslitz and Scherf, 2021), with some accessions sold under registered names and others simply described as such, sold as semolina or processed foods, with a wide market, especially in Western Countries where they can be found even in the large-scale distribution.

Furthermore, both Polish and Khorasan wheats, being able to be grown organically and adaptable to different environments, represent attractive and alternative crops for the marginal areas of Mediterranean basin, which were no longer widely cultivated due to the low grain yields compared with modern wheat cultivars. However, traditional (mostly local) farmers have continued to grow them to use in low-input agriculture, and they are a source of genetic diversity (Ganugi et al., 2021). Moreover, they are important for economic reasons, because heritage wheats respond to the demand of a specific niche of consumers, careful to the need of conserving cultural habits, often associated by people with the concept of a healthier lifestyle.

Heritage wheats are typically consumed as whole wheats, and this contributes to their healthiness. In general, they have poor technological properties. This is due to the poor-quality gluten proteins and to the presence of fibers, mostly present in the outer pericarp. Because heritage wheats are mostly consumed as whole-wheat leavened products, this affects gluten formation and gas-retention capacity, because they absorb most of the water available (Li et al., 2014; Cappelli et al., 2019; Cappelli and Cini, 2021).

Regarding health-related compounds, the situation is rather controversial and strongly dependent on the specific genotype taken into consideration (Shewry and Hey, 2015; Prandi et al., 2017; Ozuna and Barro, 2018; Lovegrove et al., 2020; Shewry et al., 2020), rather than to their belonging to a specific historical period. There is a strong need for further research on this matter, along with a standardization of evaluation procedures, in order to make reliable comparisons (Shewry, 2018).

Khorasan wheat is by far the most known, but Polish wheat has similar characteristics. It is highly adaptable, especially to Mediterranean climates, and, despite the name, it is mostly grown in Andalusia (Rodríguez-Quijano et al., 2003), Italy, Western Ukraine, Southern Asia, Algeria, and Ethiopia (Eticha et al., 2006). It is characterized by a high content of microelements (Bieńkowska et al., 2019) and by a higher amylose content (Rodríguez-Quijano et al., 2003) that accounts for a higher amount of resistant starch that increases the nutritional quality of derived foods.

The aim of this work is the characterization of accessions of Khorasan and Polish wheats, in comparison to durum wheats, grown for 2 years in the same environment, in terms of technological properties and factors affecting nutritional quality, such as fiber amount and the content of micro- and macro-nutrients in grains. This latter aspect will be also related to the root morphological traits of the different genotypes.

On the basis of the growing interest of consumers in wheats present before the Green Revolution, collectively named “ancient wheats,” parallel research is increasing to analyze them more in detail both from the nutritional and technological points of view (Cabas-Lühmann et al., 2023; Roumia et al., 2023).

In this paper, we have analyzed accessions of the T. turgidum group, including the subspecies T. durum or durum wheat, T. polonicum or Polish wheat, and T. turanicum or Khorasan wheat, grown in the same environment for 2 years, in terms of technological and nutrition-related aspects. Moreover, the same accessions have been hydroponically grown to test root morphology in order to possibly associate some of the characteristics that have been identified.

As regards the technological analyses, although protein and gluten contents were comparable among the accessions and in the 2 years and coherent with the average Italian cultivars (De Santis et al., 2017), the modern variety Svevo, as expected, had the best performance followed by Khor1. It is important to underline that Khor1 corresponds to the local field cultivation of KAMUT^® brand wheat; thus, it was not possible to use this name for locally produced kernels because they were obtained out of the official KAMUT^® food chain. KAMUT^® brand wheat has been selected also because of its better yield and technological performance; thus, it is expected that some of the qualitative parameters here measured are very good for Khor1 compared with that for other Khorasan or Polish wheats.

The test weight, a physical quality characteristic desirable because of its positive influence on market grade and price (Troccoli and Di Fonzo, 1999), showed a significant difference during the two crop years, with the first with significantly lower values probably due to three-fold more rainfall than in the second year. As reported in Kuzmanović et al. (2021), the 2019 season, at Nello Lupori experimental farm in Viterbo, was characterized by a high amount of rainfall and lower temperatures during the grain filling and the authors hypothesized that these conditions led to greater plant tiller number with less seed weight (meteorological data relative to the same location and years).

The yellow index was highly different among accessions, but not between the two growing seasons. This also is expected on the basis of the great heritability of this character (Colasuonno et al., 2019). In this case, also, Svevo and Khor1 showed the highest value.

The micro- and macro-nutrient amounts were measured because of their great nutritional importance (Khalid et al., 2023) and for their healthy beneficial effects such as antioxidant, anti-cancer, and anti-viral properties (Welch and Graham, 2004; Hansch and Mendel, 2009; Abbaspour et al., 2014). Furthermore, there is a common belief that ancient wheats contain a higher amount of these minerals (Shewry et al., 2016; Lovegrove et al., 2020; Shewry et al., 2020).

In our case, by considering the single accessions, the ANOVA analysis indicated that selenium variance was mostly explained by the genotype. In contrast, Lyons et al. (2005) reported that the amount of selenium in the kernels of wheat cultivars from Australia and Mexico is primarily determined by its availability and concentration in the soil. In fact, although higher concentrations of selenium, zinc, lithium, magnesium, and phosphorus were found in hulled wheat (Triticum spelta L. and Triticum dicoccum Schrank) grown together with modern bread wheats (Piergiovanni et al., 1997), several studies found no evidence for genetic variability among wheat cultivars for selenium accumulation in grain (Grela, 1996; Tveitnes et al., 1996; Zhao et al., 2009; Souza et al., 2014). However, a considerable genotypic variation and capacity in accumulating selenium, at least in root and shoot tissues, by four different tetraploid wheats, have been recently demonstrated (Coppa et al., 2023). In particular, the different selenate uptake ability was mainly explained by the differential expression of genes encoding the two high-affinity transporters (TdSultr1.1 and TdSultr1.3), which are involved in the primary uptake of sulfate (and selenate) from the growth medium (Coppa et al., 2023). In our work, by considering the different subspecies, the selenium concentration was lower in the Khorosan wheat in both growing seasons, but the differences were only partially explained by subspecies, year, and subspecies × year.

Our analyses highlighted that the accumulation of zinc among different accessions is mostly influenced by the genotype and interaction between genotype and year. This observation agrees with previous studies that reported a wider genetic variation for iron and zinc concentrations in diploid and tetraploid species such as T. monococcum, T. turgidum ssp. dicoccoides, T. boeoticum, Aegilops tauschii, T. spelta, T. turgidum spp polonicum, and some landraces (Cakmak, 2007; Velu et al., 2014).

The concentration of cadmium among different accessions is mostly influenced by the genotype and interaction between genotype and year, whereas, by considering the different subspecies, its concentration was significantly higher in durum and Khorasan wheat. This heavy metal, in recent years, has become one of the major and widespread soil pollutants due to intensive agricultural practices, unsustainable industrialization, and urbanization. Being highly toxic for plants, animals, and humans (Sarwar et al., 2010), there is growing interest in the selection of varieties that accumulate low cadmium levels. Cadmium accumulation in plants is determined by several genes that regulate mechanisms underlying its uptake, translocation, and accumulation (Tao and Lu, 2022). A class of metal transporters called Natural Resistance-Associated Macrophage Proteins (NRAMPs) was first reported in the model plant Arabidopsis thaliana involved in cadmium transport. Recently, three genes (TpNramp3, TpNramp5, and TtNramp6) encoding plasma membrane proteins involved in cadmium concentration and accumulation in the whole plant were found in T. polonicum and T. durum. Furthermore, Maccaferri et al. (2019) found that the modern durum wheats possessing the non functional copy of the TdHMA3-B1A gene accumulated higher amount of cadmium. Together, these results suggest that there are allelic variants in these genes in the different subspecies that regulate cadmium accumulation.

In general, by considering the different subspecies, the effect of the year among the three groups of subspecies was significant for all the minerals.

Finally, the results showed that the most interesting accessions were the following: Pol2, which accumulated the largest amount of zinc, magnesium, iron, and copper and had the lowest concentration of cadmium during the two seasons; Tur5, which showed the greatest accumulation of zinc, copper, and cadmium and the lowest accumulation of selenium; Senatore Cappelli, which accumulated a low amount of magnesium and copper but a high amount of cadmium; and Pol304, which showed high accumulation of iron and selenium. Interestingly, Pol2 showed the highest level of iron accumulation in root tissues, most likely suggestive of a significant apoplastic iron pool (Bienfait et al., 1985), but its iron concentration in seeds indicates a low relative efficiency of the “root-to-seed” iron transfer. Nutrient acquisition by roots is a key component of nutrient use efficiency (NutUE), but it is not the only one at least for iron. Indeed, it has been demonstrated that although the supply of iron from soil to the root apoplast should be adequate, the transport from the apoplast to the symplast is often impaired (Mengel, 1994); thus, even if a plant shows high concentrations of iron at root level, it can, however, show iron deficiency symptoms (Kosegarten and Koyro, 2001). High amounts of extraplasmatic iron have been detected in the roots of plants grown in nutrient solution (Bienfait et al., 1985), because, in roots, iron is mainly present as apoplastic pool, and this iron is basically adhering to the outer surface of the epidermis, probably in a particular form, and does not contribute significantly to the nutrition of the plant (Strasser et al., 1999). Furthermore, Grusak and Cakmak (2005) demonstrated that, even at high iron supply, the concentration of iron in shoot and seed could remain relatively low, likely due to limited phloem mobility. Therefore, the promising lines rich in micro- and macro-nutrients and poor in toxic elements such as cadmium identified in this study must be validated in multilocation trails. This study confirmed that a large variation in the concentrations of microelements is present among different accessions and is not solely intra-subspecies, because the environment and soil nutrient status are known to significantly affect these traits (Shewry et al., 2020).

The fibers (that include β-glucan and arabynoxylan) influence the quality of pasta and bakery products, due to their high capacity to bind the water present in the dough and to increase its viscosity. Furthermore, they have numerous beneficial physiological effects for humans, i.e., reduction of blood cholesterol, attenuation of blood glucose levels, and elevated prebiotic activity (Botticella et al., 2021). We found that, by considering the single accessions, the main contribution to the differences in WE-AX and β-glucan content was due to genotype, whereas TOT-AX content was mostly influenced by genotype-by-year interaction, in addition to by genotype. These results agree with the previous studies reported by Marion and Saulnier (2020). In general, Lovegrove et al. (2020), by analyzing 39 wheat cultivars dated between 1790 and 2012, showed that the environment affects the accumulation of health-related components, among which arabinoxylans, to a great extent. Instead, considering the subspecies, only for TOT-AX and β-glucan, there were significant effects, and, only for WE-AX and β-glucan, there were significant effects for the year. No significant effects were found for the interaction subspecies × year. In both growing season, durum wheats showed the highest content of β-glucan and TOT-AX, whereas there are no difference among the subspecies for the WE-AX content.

Root system plays a crucial role in plant fitness as roots are responsible for the efficient uptake of water and mineral nutrients. Therefore, root development and morphology were related to quality parameters (in terms of yield and technological and nutritional quality). In particular, the S/R is a measurement of the amount of shoot biomass (growth function) compared with the amount of root biomass (supportive function) and is generally maintained within a certain balance that is characteristic of the species. However, in this study, only the modern variety Svevo showed a well-balanced S/R, thus an optimal distribution of resources between the aboveground and belowground portions of the plant. This allocation should enable more efficient utilization of water and nutrients. On the other hand, the lowest values of all measured root morphological traits were observed in Svevo. Tur21 and Tur26 clustered together and showed the highest values of all morphological traits, as well as Pol2 and Pol6 clustered together and showed an increase in all roots morphological parameters compared with Svevo. Nutrient uptake in plants is, in fact, closely related to root morphology. In particular, the length and surface area of plant roots, as well as the number of root hairs, are directly related to their capacity to absorb nutrients. Therefore, although Pol2 had a lower root biomass, the particular morphology of the roots is more efficient for nutrient uptake, as evident from the greater accumulation of micro- and macro-nutrients.

In conclusion, the two accessions of Polish wheat Pol2 and Pol6 have a potential good technological quality. Moreover, Pol2 is rich in health- related micro- and macro-nutritients and poor in toxic ones Thus, these two accessions may be taken into consideration for the development of new varieties.

More information about dynamics of iron distribution in shoots and seeds is crucial to guide the exploitation of these findings to possibly improve the nutritional value of grains by increasing iron content. Thus, further experiments will explore the diversity of these wheats, with special interest in their relative efficiency of the “root-to-shoot” and “shoot-to-seed” iron transfer.

Finally, these results confirm that it is not possible to draw general conclusions about the difference between old and modern wheats, but rather a case-by-case approach should be taken into consideration, by including both the different genotypes and growing conditions.

The original contributions presented in the study are included in the article/ Supplementary Material . Further inquiries can be directed to the corresponding authors.

DL, FS, and SM: conceptualization; SP and MB: analysis of mineral and fiber content; AC: quality-related analysis, GQ and SA: root characteristics analyses, SP, MB, AC, GQ, SA, FS, and SM: writing the original draft; SP, MB, AC, GQ, SA, DL, FS, and SM: review and editing. All authors contributed to the article and approved the submitted version.