**1. Introduction**

Plum is one of the main groups of fruits with about 6000 cultivars, belonging to 19–40 species, originating from Europe, Asia, and the USA [1–5].

Plums are appreciated for fresh consumption and also for dehydration and processing in the different forms (jams, compotes, jellies, candied fruits, frozen fruits, liqueurs, brandy, etc.) [6].

Plums are the fruits with the highest nutritional value, having a high content in carbohydrates, minerals, and vitamins that stimulate the body's health [3, 7].

Fresh fruits contain sugar (16–20%), proteins (0.7%), lipids (0.28%), pectins and tanoid substances, etc. Dehydrated fruits have a high content in sugar in competition with figs and jujube (**Table 1**).

Recent studies at Tuft University, Boston, have shown that dehydrated plums have the highest antioxidants content, contributing to the neutralization of free radicals and thus to the prevention of cancer.

The therapeutic and prophylactic value of plums has been known since ancient times; they have alkalizing, mineralizing, laxative, diuretic actions.

Plum genetics and breeding have been reviewed over time by different specialists: Cullinan (1937), Weinberger (1975), Ramming and Cociu (1991), Okie and Weinberger [8], Okie and Ramming [9], Okie and Hancock (2008), Hartmann and Neumuller (2009), Neumuller (2010), Topp et al. [5], Butac et al. [10], Milosevic and Milosevic [3]. During the time, in the plum breeding programs, these researchers change different knowledge, breeding techniques, biological material, etc.


#### **Table 1.**

*Chemical composition of plums.*

#### **2. Economic importance**

Currently the world area planted with plum is 2,619,471 ha, which is up from the 1980s. Of the continents, the largest plum growing are Asia (2,125,006 ha) and Europe (353,919 ha) (**Figure 1**).

The situation in the countries is as follows: China 1,987,284 ha; Serbia, 72,024 ha; Romania, 66,680 ha; and the USA. 25,500 ha (**Table 2**).

In the world production, plum has about 2%, practically a modest place. As a temperate species, it still occupies the fourth place, after the apple, pear and peach, in this area. Plum production increased to 11,758,135 tons in 2017 (**Figure 2**). Due to the main contribution to this growth, Asia has practically become the largest producer of plums (8201 million tons, respectively, 69.75% of the world production), followed by Europe (2199 million tons, respectively, 18.70% of the world production), the USA (423 million tons), etc. (**Table 2**). It should be noted that while the average plum yield in Asia increased, the one in Europe has decreased by 5%.

According to data reported in December 2019 by FAO Yearbook, the largest producing countries (in thousand tons) are China (6804), Romania (434), the USA (423), Serbia (330), Turkey (292), Italy (207), France (205), Ukraine (200), Spain (172), the Russian Federation (146), the Republic of Korea (83), the Republic of Moldova (76), Bosnia and Herzegovina (74), Poland (58), Hungary (43), Bulgaria (49), and Germany (24) (**Table 2**).

China is the country with the fastest development in the plum production, but the major producers of plums, from *Prunus domestica* and *Prunus insititia* species, are Romania, Serbia, the Republic of Moldova, Spain, Russia, Poland, France, Germany, and Bulgaria alarming declines in plums production. These decreases are due to the competition of the citrus, peaches, bananas, and other fruits but especially to the viral diseases that have destroyed the plum orchards and depreciated fruit

*Production/yield quantities of plums and sloes in the world (total): 1994–2017. Source: [11].*

*Area and production of plums in the world and in major growing countries.*

**World/country Surface (ha) Production (thousand tons)**

**Total 2,619,471 11,758** Asia 2,125,006 8201 Europe 353,919 2199 SUA 25,500 423 China 1,713,600 5664 Romania 66,680 434 Serbia 72,024 330 Turkey 21,385 292 France 16,958 205 Italy 12,676 207 Ukraine 18,000 200 Spain 15.199 172 Russian Federation 36,442 146 Republic of Korea 7495 83 Republic of Moldova 15,955 76 Bosnia Herzegovina 38,081 74 Poland 14,344 58 Bulgaria 6805 49 Hungary 7980 43 Germany 4191 24 United Kingdom 640 13

quality in those countries.

**Table 2.**

*Plum Breeding*

*DOI: http://dx.doi.org/10.5772/intechopen.92432*

**Figure 2.**

**5**

**Figure 1.** *Production share of plums and sloes by region: average 1994–2017. Source: [11].*

#### *Plum Breeding DOI: http://dx.doi.org/10.5772/intechopen.92432*


#### **Table 2.**

**2. Economic importance**

*Chemical composition of plums.*

**Water content %**

Dehydrated fruits

Prunus

Dehydrated fruits

**Table 1.**

**Figure 1.**

**4**

**Pectic substances (%)**

Flesh fruits 87 0.7 0.28 16-20 75

**Fat substances (%)**

28 2.1 0.6 65-70 255

Flesh fruits 350 0.03 0.03 0.5 10 12 18 0.5 0.1 170

**Carbohydrates (%)**

A B1 B2 B6 C Ca P Fe Na K

1600 0.09 0.17 0.2 3.0 51 79 3.9 8.0 604

**Vitamins (mg %) Mineral substances (mg %)**

**Calories**

Europe (353,919 ha) (**Figure 1**).

(49), and Germany (24) (**Table 2**).

Romania, 66,680 ha; and the USA. 25,500 ha (**Table 2**).

*Production share of plums and sloes by region: average 1994–2017. Source: [11].*

Currently the world area planted with plum is 2,619,471 ha, which is up from the

The situation in the countries is as follows: China 1,987,284 ha; Serbia, 72,024 ha;

In the world production, plum has about 2%, practically a modest place. As a temperate species, it still occupies the fourth place, after the apple, pear and peach, in this area. Plum production increased to 11,758,135 tons in 2017 (**Figure 2**). Due to the main contribution to this growth, Asia has practically become the largest producer of plums (8201 million tons, respectively, 69.75% of the world production), followed by Europe (2199 million tons, respectively, 18.70% of the world production), the USA (423 million tons), etc. (**Table 2**). It should be noted that while the average plum yield in Asia increased, the one in Europe has decreased by 5%. According to data reported in December 2019 by FAO Yearbook, the largest producing countries (in thousand tons) are China (6804), Romania (434), the USA (423), Serbia (330), Turkey (292), Italy (207), France (205), Ukraine (200), Spain (172), the Russian Federation (146), the Republic of Korea (83), the Republic of Moldova (76), Bosnia and Herzegovina (74), Poland (58), Hungary (43), Bulgaria

1980s. Of the continents, the largest plum growing are Asia (2,125,006 ha) and

*Area and production of plums in the world and in major growing countries.*

*Production/yield quantities of plums and sloes in the world (total): 1994–2017. Source: [11].*

China is the country with the fastest development in the plum production, but the major producers of plums, from *Prunus domestica* and *Prunus insititia* species, are Romania, Serbia, the Republic of Moldova, Spain, Russia, Poland, France, Germany, and Bulgaria alarming declines in plums production. These decreases are due to the competition of the citrus, peaches, bananas, and other fruits but especially to the viral diseases that have destroyed the plum orchards and depreciated fruit quality in those countries.

### **3. Origin and history of plum**

Plums belong to the genus *Prunus* L., subfamily Amygdaloideae (syn. Prunoideae), and family Rosaceae Jussieu [3, 12]. The basic chromosome number of plum is 8 (x = 8). Plum is a member of *Prunophora* subgenus, which itself is subdivided into the sections Prunocerasus and Euprunus. The Prunocerasus section contains the following species: *P. americana*, *P. angustifolia*, *P. hortulana*, *P. munsoniana*, *P. mexicana*, *P. nigra*, and *P. maritima*. The Euprunus section contains the following species: *P. domestica*, *P. spinosa*, *P. cerasifera*, *P. salicina*, *P. cocomilia*, *P. insititia*, *P. simonii*, and *P. ussuriensis* (**Table 3**).

Plum has a large spreading area. According to Vavilov's research, there are three spreading centers for plum species: Euro-Asian, North American, and East Asian [13].

In the Euro-Asian center, the following species are present: *Prunus domestica*, *Prunus insititia*, *Prunus spinosa*, and *Prunus cerasifera*, which are widespread in South Europe, Western Asia, around the Caucasus Mountains, and Caspian Sea, but also in the Balkans, as well as in the Mediterranean countries.

In the North American center which starts from the Gulf of Mexico and the West coast of the USA to Canada in the North, the following species are spreading: *Prunus nigra*, *Prunus americana*, and *Prunus munsoniana*.

The third center, East Asian, includes the following species: *Prunus ussuriensis*, *Prunus salicina*, and *Prunus simonii*.

From this large diversity, the most important species in commercial orchards are European or domestic plum (*Prunus domestica* L.; hexaploid species with 2n = 6x = 48) and Japanese plum (*Prunus salicina* Lindl.; diploid species with 2n = 4x = 16) [4, 5, 8, 14, 15]. European and Japanese plums belong to the same taxonomic section, but they are differentiated by origin and requirements to environmental factors.

The European plum is the most important plum in Europe, but it is also grown on other continents. The origin place of this species is Caucasus Mountains near the Caspian Sea [3]. These species grown in cooler areas can be divided into several groups considering the fruit characters: plumes, prunes, greengages or reineclaudes and mirabelles [16].

Crane and Lawrence [17] suggested that *Prunus domestica* (2n = 6x = 48, genome formula CCSSSS) is genetically a hybrid between diploid cherry plum (*Prunus cerasifera* Ehrh. 2n = 2x = 16, genome formula CC) and tetraploid sloe or blackthorn (*Prunus spinosa* L., 2n = 4x = 32, genome formula SSSS) based on the fact that these species grow together in the Caucasian forests and can naturally hybridize with each other [3, 14, 18]. The same idea was supported by Rybin and Jukovsky, but later Georges Salesses questioned this hypothesis [18]. The origin of *P. domestica* remains somehow mysterious. There are three subspecies within *P. dome*stica: ssp. *insititia* (mirabelles and the so-called spilling), ssp. *oeconomica* (prunes), and ssp. *italica* (plums, reineclaudes, and all other kinds of plum fruits) [18].

For European plum, the plum fruits are round to oval, in different sizes and colors; the flesh is juicy, soft, and mostly clingstone; and the ripening time is earlier than those of prunes, but there are also some exceptions [16]. *Prunus domestica* is a very good source of genes for high sugar content, fruit flavor, late blooming, and high productivity but must be improved for frost and disease resistance (especially virus diseases) [14, 19].

various, mostly large and firm with yellow base color overlaid by red and purple,

*P. nigra* Aiton Canadian plum Canada, USA 16 *–*

*Plum species with their common name, origin, and chromosome number. Sources: [5, 6, 19–21].*

**Species Common name Origin Chromosome**

Cherry plum, Myrobalan

*DOI: http://dx.doi.org/10.5772/intechopen.92432*

European plum

mirabelle, reineclaude (gage plum)

(Chinese) plum

Apricot plum, Simon plum

Ussurian (Manchurian) plum

Common wild plum

*P. spinosa* L. Blackthorn, sloe Europa, North Africa, West

*P. domestica* L. Garden plum,

*P. insititia* L. Bullace, damson,

*P. salicina* Lindl. Japanese

*P. cerasifera* Ehrh.

*Plum Breeding*

*P. monticola* Koch

*P. simonii* Carriere

*P. ussuriensis* Kovalev and Kostina

*P. americana* Marshall

*P. angustifolia* Marshall

Bailey

*P. maritima* Marshall

*P. mexicana* S. Wats.

*P. munsoniana* Wight and Hedrick

**Table 3.**

**7**

*P. hortulana* L.H.

**1 2 3 45**

*P. cocomilia* Ten. Italian plum Italy, Serbia 16 –

West Asia, Balkans (Serbia, Romania, Bulgaria, Greece), Caucasus

Taurus plum Asia 16 –

Asia

East USA, to the Rocky Mountains

Florida); Illinois, Texas

to the Iowa, Oklahoma, Texas, Louisiana); Alabama

Kentucky)

Beach plum USA (Virginia) 16 *flava* (with

Big-tree plum USA, Mexico 16 *polyandra*,

Chickasaw plum USA (New Jersey to the

Hortulan plum USA (Kentucky, Tennessee

Wild Goose plum USA (Texas, Ohio,

**number**

Europe, West Asia 48 –

Europa, West Asia 48 *subsylvestris*,

China 16 (32) –

North China 16 *purpurea*

China 16 –

32 (16, 24, 48) –

16 *mollis*, *lanata*

16 *watsonii*, *varians*

16 *mineri*, *pubens*

16 –

yellow fruit)

*fultonensis*

16 (24, 32, 48) *atropurpurea*,

**Subspecies/ varieties**

*pissardi, pendula*, *elegans*, *divaricata*

*italica*, *syriaca*

Breeding new plum cultivars needs to anticipate the future requirements from

very attractive, designated for the fresh market [1, 14].

**4. Breeding objectives**

the growers, market, and consumers.

Japanese plum has its origins in China (Yangtze River Basin), but for about 2000 years, it has been cultivated in Japan [1]. This species grew in warmer areas. It was imported to California in North America by Hough in 1870. The famous plum breeder Luther Burbank started his breeding in 1875 using all species available and produced thousands of seedlings and selected a lot of varieties [16]. The fruits are


*Plum Breeding DOI: http://dx.doi.org/10.5772/intechopen.92432*

**3. Origin and history of plum**

Prunus

*Prunus salicina*, and *Prunus simonii*.

environmental factors.

and mirabelles [16].

virus diseases) [14, 19].

**6**

*P. insititia*, *P. simonii*, and *P. ussuriensis* (**Table 3**).

in the Balkans, as well as in the Mediterranean countries.

*Prunus nigra*, *Prunus americana*, and *Prunus munsoniana*.

Plums belong to the genus *Prunus* L., subfamily Amygdaloideae (syn.

plum is 8 (x = 8). Plum is a member of *Prunophora* subgenus, which itself is

contains the following species: *P. americana*, *P. angustifolia*, *P. hortulana*, *P.*

Prunoideae), and family Rosaceae Jussieu [3, 12]. The basic chromosome number of

subdivided into the sections Prunocerasus and Euprunus. The Prunocerasus section

*munsoniana*, *P. mexicana*, *P. nigra*, and *P. maritima*. The Euprunus section contains the following species: *P. domestica*, *P. spinosa*, *P. cerasifera*, *P. salicina*, *P. cocomilia*,

Plum has a large spreading area. According to Vavilov's research, there are three spreading centers for plum species: Euro-Asian, North American, and East Asian [13]. In the Euro-Asian center, the following species are present: *Prunus domestica*, *Prunus insititia*, *Prunus spinosa*, and *Prunus cerasifera*, which are widespread in South Europe, Western Asia, around the Caucasus Mountains, and Caspian Sea, but also

In the North American center which starts from the Gulf of Mexico and the West coast of the USA to Canada in the North, the following species are spreading:

The third center, East Asian, includes the following species: *Prunus ussuriensis*,

From this large diversity, the most important species in commercial orchards

The European plum is the most important plum in Europe, but it is also grown on other continents. The origin place of this species is Caucasus Mountains near the Caspian Sea [3]. These species grown in cooler areas can be divided into several groups considering the fruit characters: plumes, prunes, greengages or reineclaudes

Crane and Lawrence [17] suggested that *Prunus domestica* (2n = 6x = 48, genome

For European plum, the plum fruits are round to oval, in different sizes and colors; the flesh is juicy, soft, and mostly clingstone; and the ripening time is earlier than those of prunes, but there are also some exceptions [16]. *Prunus domestica* is a very good source of genes for high sugar content, fruit flavor, late blooming, and high productivity but must be improved for frost and disease resistance (especially

Japanese plum has its origins in China (Yangtze River Basin), but for about 2000 years, it has been cultivated in Japan [1]. This species grew in warmer areas. It was imported to California in North America by Hough in 1870. The famous plum breeder Luther Burbank started his breeding in 1875 using all species available and produced thousands of seedlings and selected a lot of varieties [16]. The fruits are

formula CCSSSS) is genetically a hybrid between diploid cherry plum (*Prunus cerasifera* Ehrh. 2n = 2x = 16, genome formula CC) and tetraploid sloe or blackthorn (*Prunus spinosa* L., 2n = 4x = 32, genome formula SSSS) based on the fact that these species grow together in the Caucasian forests and can naturally hybridize with each other [3, 14, 18]. The same idea was supported by Rybin and Jukovsky, but later Georges Salesses questioned this hypothesis [18]. The origin of *P. domestica* remains somehow mysterious. There are three subspecies within *P. dome*stica: ssp. *insititia* (mirabelles and the so-called spilling), ssp. *oeconomica* (prunes), and ssp. *italica*

(plums, reineclaudes, and all other kinds of plum fruits) [18].

are European or domestic plum (*Prunus domestica* L.; hexaploid species with 2n = 6x = 48) and Japanese plum (*Prunus salicina* Lindl.; diploid species with 2n = 4x = 16) [4, 5, 8, 14, 15]. European and Japanese plums belong to the same taxonomic section, but they are differentiated by origin and requirements to

#### **Table 3.**

*Plum species with their common name, origin, and chromosome number. Sources: [5, 6, 19–21].*

various, mostly large and firm with yellow base color overlaid by red and purple, very attractive, designated for the fresh market [1, 14].

### **4. Breeding objectives**

Breeding new plum cultivars needs to anticipate the future requirements from the growers, market, and consumers.

#### Prunus

A large number of breeding programs are developed in many countries from Europe (**Table 4**). Some of plum breeding programs have been reduced or stopped in the countries where production has declined or funding is no longer available. At the same time, some breeding programs became more private with less public funding [22].

**Country Breeding centers Breeder Objectives**

M. Butac M. Botu I. Zagrai

N. Milosevič I. Glisič T. Milosevič

W. Hartmann M. Neumuller H. Jacob

R. Renaud

S. Sansavini E. Bellini V. Nancetti A. Liverani

R. Jones T. Laxton

V. Bozhkova A. Zhivondov

E. Kaufmane I. Gravite L Ikase

V.A. Matveev M. Vasiljeva

T. Jakubowski E. Zurawicz J. Dominikowski E. Rozpara Z. Grzyb J. Szymanski

R. S. Zaremuk E. M. Alekhina G. Eremin

M. Pintea, A. Juraveli - Improvement of old cvs. Tuleu gras, Grase

romanesti, Vinete romanesti
















J. Blazek - Fruit quality



Japanese and European plum breeding program: - Fruit quality - Fresh consumption - Resistance to PPV

Pozegača

**1 2 3 4**

Romania Research Institute for Fruit Growing,

*DOI: http://dx.doi.org/10.5772/intechopen.92432*

Serbia Fruit Research Institute, Cacak Faculty of Agronomy, Cacak

Germany University of Hohenheim, Stuttgart

Bulgaria Fruit Growing Institute, Dryanovo Fruit Growing Institute, Troyan Fruit Growing Institute, Kyustendil Fruit Growing Institute, Plovdiv

Latvia Latvia State Institute of Fruit Growing,

Italy University of Bologna University of Firenze University of Forli Private program

Dobele

United Kingdom

Republic of Moldova

Czech Republic

**9**

Hochschule Geisenheim University

France INRA, Bordeaux R. Bernhard

East Malling Research Station, Kent K. Tobutt

Belarus Institute for Fruit Growing, Minsk Z. Kazlouskaya

Research Institute for Horticulture and Alimentary Technologies, Chisinau

Research and Breeding Institute of

Pomology, Holovousy

Poland Research Institute of Horticulture, Skierniewice

Russia North-Caucasus Zonal Horticulture and

Viticulture Research Institute, Krasnodar Krymsk Experiment Breeding Station,

Fruit Growing Research Station, Valcea Research Station for Fruit Growing,

Pitesti

*Plum Breeding*

Bistrita

The breeding objectives are general and specific. The general objectives include the following:


The special objectives concern the following (**Table 3**):


Eighty percent of all breeding activities are carried on by *Prunus domestica* and only twenty percent by *Prunus salicina* [2, 13, 23–25].
