**2. Origin of potato**

Bengal, Punjab, Bihar, Haryana, Madhya Pradesh, Gujarat and Maharashtra. Total potato production is about 320 million tonnes (Mt) globally, of which about 66% is used as food, 12% as feed and 10% as seed [2]. At the highlands of Ethiopia, the potato holds great promise for improving the livelihoods of millions of smallholder farmers. The potential for high yield, early maturity and excellent food value give the potato great potential for improving food security, increasing household income and reducing poverty [3]. Potato is grown in India in almost all the states except Kerala. It is possible to see the crop in field round the year in one part of the country or the other. About 82% of the area under potato crop lies in the plains where the crop is grown during short-days of winters from October to March. About 10% lies in the hills where the crop is grown during long-days of summer from April to September in

Cultivated potato and its wild relatives belong to the genus *Solanum*, the largest genus with 1500–2000 species [4]. Within the genus *Solanum*, over a 1000 of species have been recognized [5]. The genus *Solanum* comprises 8 cultivated species and 2000 wild relatives out of which

The tuber-bearing *Solanum* species are grouped in the *Petota* section. This section is divided into two sub-sections, *Potatoe* and *Estolonifera* [6]. The sub-section *Potatoe* contains all tuberbearing potato species, including common potato (*S. tuberosum*, belonging to series *Tuberosa*). Two non-tuber bearing series (*Etuberosa* and *Juglandifolia*) are placed in sub-section *Estolonifera*. However, a number of molecular studies suggest that the series *Etuberosa* and *Juglandifolia* do

The cultivated potato (*S. tuberosum*) is divided into two sub-species: *tuberosum* and *andigena*. The sub-species *tuberosum* (**Table 1**) is the cultivated potato originated from Peru and widely in use as a crop plant in, for example, Asia, North America and Europe. The sub-species *andigena* is also a cultivated species, originated from Andean mountain (South America) and cultivation is restricted to Central and South America [6, 9]. The subsp. *andigena* forms tubers under short day conditions at high altitudes (>2000 msl.) while in the subsp. *tubersoum,* tuber formation is under long days in temperature climate and short days in the tropics at lower altitudes (500–2000). The cultivated potato (*S. tuberosum* subsp. *tuberosum*) is crossable with other cultivated species

tropical and sub-tropical parts of the world.

235 *Solanum* species tuberize.

38 Potato - From Incas to All Over the World

not belongs to the *Petota* section [7, 8].

**Taxonomic rank Latin name** Family Solanaceae Genus *Solanum* Section *Petota* Subsection *Potatoe* Series *Tuberosa*

Species *Solanum tuberosum*

Sub-species *tuberosum*

**Table 1.** Taxonomic position of *S. tuberosum* subsp. *tuberosum*.

Potato is an auto-tetraploid species (2n = 4× = 48) which was first introduced into Europe, and spreads as a botanical novelty and as fodder crop for livestock. Initially people treated the potato as suspicion relative of the toxic nightshade (*S. nigrum*).Eventually potato was adopted as a human food source and gradually gained popularity and then it introduced to the rest of the world, from the Andes of South America in the late sixteenth century. By the end of the eighteenth century, it was found that it is well adopted under long-day photoperiod then further selection of early tuberization cultivars and high-yielding clones were done from the derived seedlings from naturally occurring berries, the consequence of uncontrolled, largely self-pollination. Potato is an Andean tuber crop that was originally domesticated in South America and started its worldwide dissemination after Columbus voyages brought to Europe in the late sixteenth century some years after the discovery and conquest of Peru. It is believed that cultivated potato originated from its wild ancestors near the lake *Tritica* basin in Peru Bolivian region in high mountains. This plant was selected as article of food by the oldest civilizations of Mayas and Incas. There are strong evidences that potato was widely distributed throughout the Andes, from Colombia to Peru and also in southern Chile. Potatoes are said to have been taken to India and to China by British missionaries in the late seventeenth century and were known in Japan and parts of Africa by about the same period.

Potato was originated from the wild species *Solanum leptophyes* some 10,000–7000 years ago, and the first domesticated species was *Solanum stenotomum.* The evolution of *Solanum stenotomum* was only the beginning of potato evolution. In addition to first wild species *S. leptophyes*

which gave rise to domesticated diploid species, *Solanum stenotomum*, three otherswild species, namely *S. sparsipilum, Solanum acaule* and *Solanum megistacrolobum* were instrumental in evolution of present day cultivated potatoes. Some authors believed that *S. tuberosum* is a straight tetraploid of *S. stenotomum*but there are stronger evidences in support of the allotetraploid origin of *S. tuberosum* by hybridization between *S. stenotomum* and *S. sparsipilum* [11].

which enhance colon health and lower the risk of colorectal cancer and diverticulosis. The diploid potato species adapted to long-day growing conditions, the concentration of amylose in starch ranged from 25 to 36%. Greater variations for amylose content were present in wild potato species, which ranged from 22 to 43%. There is considerable interest in the potential of potato to lessen micronutrient malnutrition, particularly for iron and zinc. About 40% of the world's population is iron deficient, however, no reliable estimate is available for the number of people with zinc deficiency. The iron content of potato ranges from 15 to 20 μg/g DW. However, iron concentrations ranging from 9 to 158 μg/g DW in Andean potato cultivars

Breeding Potato for Quality Improvement http://dx.doi.org/10.5772/intechopen.71482 41

Breeding of potato is a cumbersome task due to inherent genetic and biological factors. To understand the genetics, we will first outline some important genetic and reproductive aspects of the potato. Potato has basic chromosome number as 12 and right from diploid to hexaploid species. Majority (about 73%) of the species are diploid followed by tetraploids (about 15%), hexaploids (about 6%), triploids (about 4%) and pentaploids (about 2%). The tuber-bearing *Solanum* species include several diploids (2n = 24), triploids (2n = 36) and a few tetraploids (2n = 48), and hexaploids (2n = 72). Many wild species of the series *Tuberosa* are diploid (*S. berthaultii, Solanum canasense, S. sparsipilum, S. vernei,* etc.) and the cultivated diploid (2n = 2× = 24) species*, S. stenotomum*, *S. phureja and S*. *ajanhuri*, of which former two are sexually fertile and the later one is less fertile and does not breed true. Triploid potato species are *S. chaucha* and *S. xjuzepczukii* derived from spontaneous crosses between diploid and tetraploid species. There are 3 cultivated diploid species, *S. stenotonomum, S. phureja* and *S.ajanhuri*. The cultivated potato *S. tuberosum and S. demissum* are autotetraploid species with chromosome number, 2n = 4× = 48 are usually fertile except in a number of highly bred clones outside South America. There is only one pentaploid species (2n = 60), that is, *S. curtilobum* which is reasonably fertile in crosses with *S. tuberosum*, but not in selfings. Nearly all the diploid species are self-incompatible while all the tetraploids and hexaploids are self-compatible [11].

Genetic diversity is a prerequisite for an effective plant breeding program. It is a useful and essential tool for parent's choice in hybridization to develop high yield potential cultivars and to meet the diversified goals of plant breeding [15]. The cultivated potato have narrow genetic base due to limited introduction of germplasm from their natural range in South America [16]. Most of the potato cultivars are auto-tetraploid (2n = 4× = 48), highly heterozygous and out breeding species, which suffer from inbreeding depression. Cultivated potato species have a base chromosome number of n = 12 and may be diploid (2n = 2× = 24), triploid (2n = 3× = 36), tetraploid (2n = 4× = 48) or pentaploid (2n = 5× = 60). There are 7 cultivated potato species [6], whereas only 9 species and 141 intra-specific taxa have been identified [17]. Recent studies suggested that, genotyping of 742 landraces of all cultivated and wild species have been completed with SSR and chloroplast markers [18]. Based on these studies,

and 18–65 μg/g DW in recent American potato cultivars.

**4.1. Genetic diversity for quality traits**

**4. Genetics and chromosomal variations of potato**

#### **3. Nutritional content of potato**

Potato tubers contain about 75% water, 21% carbohydrates (of which about 82% is starch), 2.5% protein and less than 1% fat. Often looked upon as primarily a starchy vegetable, potatoes are actually highly nutritious. It is a good source of vitamins C and B6 . About 48% daily values (DV) for vitamin C and 46% for vitamin B6 are provided by a large (299 g) baked potato. They also have fair amount of fibers (26% DV), proteins and minerals. The DVs are varied with different types of cultivars, various authors have been reported DVs of 46% for potassium, 33% for manganese, 21% for magnesium and 21% for phosphorus in large baked potato. Potatoes are rich source of essential amino acids which required for proper growth and development, hence it is considered as balanced and complete diet for adults. The flesh color varies according to genotypes and climatic conditions of cultivated area. The most common flesh color is white but other than this variety of flesh color cultivars evident in different countries. The carotenoids (yellow and orange colors) and anthocyanins (red and purple colors) are the two most valuable coloring pigments in potato. White-fleshed potatoes are low in carotenoids (<100 μg/100 g fresh weight) whereas, the carotenoid content of yellowfleshed varieties are higher (about 560 μg/100 g FW) [12]. Intense yellow to near orange flesh color, associated with carotenoid concentrations >2000 μg/100 g FW, have been reported in diploid *Solanum* germplasm [13]. The primary tuber carotenoids in potato tubers are lutein, zeaxanthin and violanxanthin, although some studies have also reported finding neoxanthin and antheraxanthin [13]. In the macula of the human eye, lutein and zeaxanthin are found and it also plays a role in reducing the risk of age-related macular degeneration. In addition, increased intake of zeaxanthin may improve mental acuity in the elderly. The anthocyanin concentration in tubers is 100-fold greater than carotenoids. The red fleshed of tubers is mainly due to the anthocyanin pigment pelogonidin-3-(p-coumaroyltutinoside)-5-glucoside (200–2000 μg/ g FW) and peonidin-3-(pcoumaroyl-rutinoside)-5-glucoside (20–400 μg/g FW) while, petunidin3-(p-coumaroyl-rutinoside)-5-glucoside (1000–2000 μg/g FW) and malvidin-3-(p-coumaroyl-rutinoside)-5-glucoside (2000–5000 μg/g FW) compounds of anthocyanin pigments are responsible for dark purple-fleshed potatoes [14]. There is increasing interest in anthocyanins in potato tubers because of their perceived higher antioxidant content, and ability to combat both prostate cancer and breast cancers. The potatoes with high glycemic index play important role in the diet of persons suffering from diabetes. During digestion, quick breakdown of food with high glycemic index leads to rapid rise of blood sugar level. The two major components of potato starch are amylose (20–25%) and amylopectin (75–80%). While cooking recrystallization of some portion of amylose leads to formation of resistance starch. Resistant starch acts as a dietary fiber. It passes through the small intestines and once in the large intestines microbial fermentation results in the production of small chain fatty acids, which enhance colon health and lower the risk of colorectal cancer and diverticulosis. The diploid potato species adapted to long-day growing conditions, the concentration of amylose in starch ranged from 25 to 36%. Greater variations for amylose content were present in wild potato species, which ranged from 22 to 43%. There is considerable interest in the potential of potato to lessen micronutrient malnutrition, particularly for iron and zinc. About 40% of the world's population is iron deficient, however, no reliable estimate is available for the number of people with zinc deficiency. The iron content of potato ranges from 15 to 20 μg/g DW. However, iron concentrations ranging from 9 to 158 μg/g DW in Andean potato cultivars and 18–65 μg/g DW in recent American potato cultivars.
