**1. Introduction**

Often considered a central argumen<sup>t</sup> in the scientific debates at a local or global scale, the biodiversity loss issue is becoming a critical challenge that needs to be carefully considered in future years. Following this debate, the newly launched EU Biodiversity strategy has put forward measures to address the biodiversity loss across the European Union [1]. Within this issue, a lively interest has been addressed towards the agro-biodiversity, which includes cultivated species and landraces, wild flora, soil microorganisms, pollinators, and the relative interconnections between plant and environment or genetic resources and agricultural management/practices [2]. Furthermore, local knowledge and culture also have an important role and should be considered part of agro-biodiversity [2].

Localized in the central part of the Mediterranean area, Italy offers a wide variety of ecological, pedoclimatic, and orographic conditions. The Italian flora is characterized by rare and endemic plants, with many domesticated crops and vegetables showing high genetic and phenotypic variability [3]. In the Italian territory, particularly South Italy, small family-owned farms and rural areas are rich in vegetable germplasm, represented by wild flora, different landraces, and plant species closely linked to the local historical memory [3].

The neglected and underused plant species (NUS) are cultivated varieties, semidomesticated, or wild plant species that tend to be underutilized locally or globally, due to their relatively low value for the global production and marketplace, since they most often do not meet the modern standards of uniformity [4] as major cultivated varieties [4–7]. Indeed, starting from the Green Revolution, we assisted the decline of many local/traditional species and varieties, which were less competitive compared with commercial cultivars, and, therefore, they have been replaced by high-yielding and uniform cultivars developed by modern breeding programs [2,7]. This genetic erosion has been also amplified by urban

**Citation:** Scarano, A.; Semeraro, T.; Chieppa, M.; Santino, A. Neglected and Underutilized Plant Species (NUS) from the Apulia Region Worthy of Being Rescued and Re-Included in Daily Diet. *Horticulturae* **2021**, *7*, 177. https:// doi.org/10.3390/horticulturae7070177

Academic Editors: Rosario Paolo Mauro, Carlo Nicoletto and Leo Sabatino

Received: 4 June 2021 Accepted: 28 June 2021 Published: 3 July 2021

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spreading, changes in socio-economic conditions, and destruction of natural environments due to increased human activities [3].

As a source of vitamins, micronutrients, and other phytochemicals, NUS have the potential to play a strategic role for addressing nutritional security challenges [6]. A wider use of NUS would also enhance adaptability and resilience to biotic and abiotic stress factors and ultimately might lead to a more sustainable supply of diverse and nutritious foods [8]. In fact, many autochthonous plant species are characterized by a high nutritional value compared to cultivars or similar species belonging to the same family.

Furthermore, landraces and wild relatives can provide genetic traits that are useful for increasing biotic resistance and tolerance to abiotic stress in future breeding programs, especially when creating more sustainable and resilient production systems [9–12].

In this review, we focus on some examples of NUS from the Apulia Region (Southern Italy), either cultivated landraces or spontaneously growing as a part of the local flora, that are worthy of being rescued and enhanced for their interesting nutritional properties and economical potential.

### *1.1. Multicolored Carrots*

Carrot (*Daucus carota* L.) is one of the most popular and consumed root vegetables worldwide and it is especially known in Western dietary regimes as an important source of dietary carotenoids, such as α-carotene and β-carotene, which are also known as provitamin A [13]. In fact, the popularity of carrots is mainly linked to their nutritional value, which makes them an economically important horticultural crop.

Carrot is consumed as a fresh vegetable, used in many traditional dishes or soups, commercially transformed into juices and concentrates, canned, or dried powdered [14]. Although the most common genotypes are orange-colored, in some countries, such as those in southern Europe, Turkey, China, or India, multicolored carrots are also well known [15]. In fact, the primary genotypes of carrots were yellow or purple and they originally spread from Afghanistan across the Middle East, North Africa, Europe, and China. During the domestication processes, yellow carrots have been preferred, leading to the final development and cultivation of orange carrots, the most prevalent at present [15–17]. On the other hand, black/purple carrots (*Daucus carota* ssp. *sativus* var. *atrorubens* Alef.), deriving from the primary domestication center and pigmented both in the epidermis and the inner central core of the taproots, are still cultivated and highly appreciated in some countries and represent one of the most used anthocyanin sources as food colorant, due to the high stability of the processing conditions and storage [18].

In Italy, some documents report the presence of multicolored carrots through 13th and 14th centuries [16]. In the Apulia region, multicolored carrot landraces (Figure 1) are cultivated from local farmers in different villages, and they have been officially inserted in the list of species at risk of genetic erosion, according to the Apulian Rural Development Program (2007/2013). In particular, only three different landraces related to the area of production (Polignano, Tiggiano, and Zapponeta) have been described. In the case of Polignano landrace, these carrots are currently cultivated in an area of about 20 ha, with cultivation practices at risk due to the age of elder farmers and the difficulty for farmers to collect reproductive material/seeds. The Polignano and Tiggiano carrots have been the subject of several studies in recent years, particularly due to the anthropic cultural heritage associated with them and their high nutritional value [16–21]. In fact, their typical yellow-purple color has been associated with increased levels of some classes of polyphenols compared to the commercial orange varieties. Among the multicolored carrots, the yellow carrots have showed a slight reduction in the content of carotenoids and phenolic compounds, whereas the purple-yellow and purple-orange carrots ensure high levels of polyphenols, mainly chlorogenic acid and anthocyanins, maintaining, at the same time, a carotenoids content similar to orange carrots (Table 1) [16,18,22–24]. Due to the presence of high levels of phenolic compounds, the extracts from yellow-purple carrots have shown to be high in vitro antioxidant capacities compared to the orange carrots, but

1 their nutritional significance can be also extended to other molecular properties, since a body of evidence has associated polyphenols dietary administration to anti-inflammatory, anti-aging, and anti-tumoral effects, thus providing a preventive effect against chronic and inflammatory human diseases [23,24]. Based on these nutraceutical features, multicolored carrots represent important horticultural species that can be valorized in breeding programs aimed at biodiversity preservation and sustainable agriculture.


**Figure 1.** Scheme of the main features of multicolored carrots.

**Table 1.** Some examples of phenolic compounds, anthocyanins, and carotenoid content in multicolored carrots.


GAE: Gallic acid equivalents; 2 CGA: Chlorogenic acid; 3 KE: Kuromanin equivalents; 4 C3GE: cyanidin-3-glucoside equivalents.
