evolution description and importance of tomato previous next end

Evolution description and importance of

tomato

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Evolution description and importance of tomato

Origin

The first reference of tomato appears in 16th Century herbalistis, but

they are brief and only identify it as newly introduced into Europe.

Two hypotheses have been put forward with regard to its place of

origin.

Mullar (1940a, 1940 b) and Luckwill (1943) suggested that tomato

was transported to Europe from Peru sometime in 1535.

Only two areas have received attention as potential sites of

domestication, namely Peru and Central Mexico.

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The critical evidence cited by them is that the early names ‘Male

peruviana’ and ‘Pomi del Peru’ indicate a Peruvian origin.

On the other hand, some authors mentioned the possibility of a

Mexican origin.

Von Humbloldt (1821) mentioned tomato among a list of plants that

may probably be considered as Mexican.

Both hypotheses have been frequently quoted.

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In 1544, Mathiolus gave the common name ‘Pomi d’oro’ with its latin

equivalent ‘Mala aurea’ for the first time.

Furthermore, the name ‘Pomi d’ oro’ has persisted in Italy as the

common name of tomato.

Dodonaeus, in his Flemish edition of Herbal in 1544 described

tomato in a separate chapter entitled ‘Of Amorous apples or Golden

apples’.

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Anguillara, Semplici (1561) there is a short note entitled

‘Lycopersico di galeno’. On Anguillaras edition two new names

‘pomic del Peru’and ‘ Lycopersican’ were introduced into the

synonymy and because firmly established through repetition in

subsequent works.

infact the later name has persisted as the scientific name of the

genus for quite a long time.

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Whatever may be the geography of domestication of the tomato, its

immediate ancestor was probably var. cerasiforme as concluded by

Jenkins (1948) and still widely accepted.

He also suggested that it is reasonably certain that Mexico and not

Peru was the source of the cultivated tomatoes of the old world and

probably and only centre of domestication of the tomatoes as there

is a wide spread distribution of var. cerasiforme in Mexico.

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The var. cerasiforme also bears greater genetic resemblance to the

cultivated tomato than L. pimpinellifollium which is probably a by-

product rather than a member of the stem line of the crop.

Robert Gibbon Johanson (1820) demonstration its edibility.

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Taxonomy Class : Asteridae Super Kingdom : Eukaryota Super Order : lamiids Kingdom : Viridiplantae Order : Solanales Phylum : Streptophyta Family : Solanaceae Sub Phylum : Embryophyta Sub Family : Solanum Division : Tracheophyta Subdivision : Spermatophyta Genus : Lycopersicon Super Class : Magnoliophyta Species : esculentum


Tomato belongs to the family Solanaceae and genus Lycopersicon.

The genus includes 12 species, all native to South America. The

genus differs from Solanum by the absence of spines in the

pinnatifid leaves and anther tips are narrow and exhibit longitudinal

dehiscence.

According to Mullar (1940a) and Luckwill (1943), the genus is

further subdivided into two subgenera.

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Based on fruit colour(Mullar 1940)

Eulycopersicon : Characterized by red fruited edible species with

carotenoid pigmentation and annual. Cultivated tomato esculentum

and pimpinellifolium species are included in this group.

Eriopersicon: Green fruited species with anthocyanin pigmentation

and the following species are in this group.

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Later, Rick and Lamm (1955) emphasized the importance of

recognizing chilense as a separate species.

Two distinct species, L. esculentum and L. pimpinellifolium are

recognized by most authorities, with 4 or 5 botanical varieties in the

former(Thompson and Kelly,1957)

Based on fruit shape

Bailey (1949) classified tomatoes in to two species, L. esculentum

and L. pimpinellifolium with 5 botanical. The chromosome number of

all the species are 2n=2x=24.

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pissisi (Luckwill, 1943)

peruvianum (Mullar, 1940a)

hirsutum (Mullar, 1940a)

glandulosum (Mullar, 1940a)

cheesmanii (Mullar, 1940a)


Based on growth habit and fruit characters, five forms of L.

esculentum are identified.

Commune - Common tomato

Cerasiformae - Small fruited cherry tomato

Pyriforme - Pear shaped tomato

Grandifolium - Potato leaved tomato

Validum - Erect and upright tomato

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Rick (1976) divided genus Lycopersicon into following two

groups based on their ability to cross with cultivated tomato:

1.Esculentum complex (crossable with cultivated tomato)

L. esculentum, L. pimpinellifolium, L. cheesemani and L.

Hirsutum

2.Peruvianum complex (Not crossable with cultivated tomato)

L. peruvianum, L. chinense

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Rick (2007) of Tomato Genetic Resource Centre (TGRC) gave Solanum equivalents for the different Lycopersican species that are being maintained at this centre.

1. L. esculentum – solanum lycopersicum

2. L. esculentum var. cerasiforme – solanum esculentum var cerasiforme.

3. L. pimpinellifolium – S. pimpinellifolium

4. L. cheesmanii – S. cheesmaE

5. L. cheesmanii f.minor – S. galapaganse

6. L. chmielewskii – S. chmielewskii

7. L. parviflorum – S. neorickii

8. L. preuvianum f. humifusum - L. preuvianum

9. L. previanum f. glandulosum – S. corneliomulleri

10.L. hirsutum includes L.hirsutum f. glabratum

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New species of tomato relatives in which

the name of the species under

Lycopersicon genus is not available are

S.lycopersicoides, S.sitiens,

S.juglandifolium, S.ochranthum.

Plant Characteristics

Tomatoes are short-lived perennials

cropped as annuals.

Although killed by frost outdoors,

in greenhouses, plants can be cropped

for 24 months or longer.

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Growth habits:

determinate vs. indeterminate. The primary shoot of a young

tomato plant produces 5 to 10 leaves, then produces a flower

cluster.

Each flower cluster is referred to as a 'hand'. In indeterminate

cultivars, the shoot continues to grow upward and flower clusters

appear to develop to the side of a main shoot or main stem.

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Although indeterminate plants appear to have a single main stem,

this is actually not the case.

The growth of the primary shoot ends with the formation of the first

flower.

Upward growth continues because the last leaf initiated before the

flower cluster (which actually grows to occupy a position above the

cluster) produces a side shoot.

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This side shoot produces three more leaves before it terminates in a

flower cluster.

The process of initiating new growth from a side shoot of the last

leaf initiated before the flower cluster continues indefinitely, giving

the appearance of a main stem with a flower cluster between every

three leaves.

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Leaf characters

The tomato plant has compound leaves. A

compound leaf is made up of leaflets which are

distributed along the leaf rachis.

While the entire leaf is connected to the stem by

the petiole, the leaflets are connected to the

rachis of the leaf by the petiolule.

Some of the leaflets on this leaf are compound

as well.

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Flower character

Tomato plants have yellow flowers that, in full

bloom, are generally less than an inch in

diameter.

The flowers can occur in a simple or a complex

inflorescence.

Simple flowers can appear as well as simple

cymes and branched cymes.

The number of flowers that occur in an

inflorescence is dependent upon environmental

factors such as temperature.


Flowers are borne in raecmose cyme and flower cluster is known as` truss` and

its position is auxiliary. Flowers are hermaphrodite, pendulous, pentomerous and

hypogynous. Stamens are 6 inserted on throat of corolla tube and anthers are

connivet around style.

Calyx: Gray in colour, 5-7 sepals, alternate with petals, persistent, valvate

aestivation.

Corolla: 5-7 petals, bright yellow in colour, alternate to sepals, valvate aestivation.

Androecium: Stamens 5, greenish yellow, free at the base and united at top. The

anthers dehisce longitudinally.

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The tomato fruit is a classified

botanically as berry.

It is borne single or clusters with persistent

calyx.

Size varies from small cherry types with

only two divisions of the ovary (locules)

to large multi-locular beefsteak types.

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Fruit Characteristics.

Examples are cherry tomatoes and processing (plum or pear) types.

Cherry tomatoes are small and round and grown only for fresh

market. Processing types are usually somewhat larger and can be

pear, plum or 'square-round' in shape.

Although most processing tomatoes are canned or processed into

sauces and condiments, small percentages are also sold fresh or as

'sun-dried' tomatoes.

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Two-locules wild types:



Fruit can be yellow, orange, pink, red, or even white.

The red color comes from the pigment lycopene while

the orange and yellow colors come from betacarotene

pigments.

Yellow and orange tomatoes are equal or higher in

nutrition to red tom atoes because lycopene has no

particular nutritional value while carotenoids are a

source of vitamin A.

Pink tomatoes have the same interior color as red

tomatoes but have a transparent rather than yellow skin.

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Colour:


Fresh market tomatoes range from round to oblate (flat-round) while

processing tomatoes are more elongated (oblong) or pear-shaped.

Breeders of processing tomatoes have developed oblong types with

squarer shoulders (called square-rounds) to resist crushing. Old tomato

cultivars are of many shapes and sizes, including ridged.

Seeds:

Numerous, round in shape, yellowish in colour, with adherence of

mucilaginous substance.

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Shape:


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Nutritive value:

Tomatoes are now eaten freely throughout the world, and their

consumption is believed to benefit the heart, among other organs.

They contain the carotene lycopene,

one of the most powerful natural antioxidants.

In some studies, lycopene, especially in cooked tomatoes, has been

found to help prevent prostate cancer, but other research contradicts

this claim.

Lycopene has also been shown to improve the skin's ability to protect

against harmful UV rays.

Natural genetic variation in tomatoes and their wild relatives has given

a genetic plethora of genes that produce lycopene, carotene,

anthocyanin, and other antioxidants

http://en.wikipedia.org/wiki/Lycopene

http://en.wikipedia.org/wiki/Antioxidant

http://en.wikipedia.org/wiki/Prostate_cancer


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Tomato varieties are available with double the normal vitamin C

(Doublerich), 40 times normal vitamin A (97L97), high levels of

anthocyanin (resulting in blue tomatoes), and two to four times the

normal amount of lycopene (numerous available cultivars with the

high crimson gene).


Nutritional value per 100 g (3.5 oz)

Energy 74 kJ (18 kcal)

carbohydrates 3.9 g

Sugars 2.6 g

Dietary fibre 1.2 g

Fat 0.2 g

Protein 0.9 g

water 94.5 g

VitaminA equiv. 42 μg (5%)

lutein and Zexathien 123 μg

Vitamin C 14 mg (17%)

Vitamin E 0.54 mg (4%)

Potassium 237 mg (5%)

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Medicinal properties

Lycopene has also been shown to protect against oxidative damage

in many epidemiological and experimental studies.

In addition to its antioxidant activity, other metabolic effects of

lycopene have also been demonstrated.

The richest source of lycopene in the diet is tomato and tomato

derived products.

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Tomato consumption has been associated with decreased risk of

breast cancer, head and neck cancers and might be strongly

protective against neurodegenerative diseases.

Tomatoes and tomato sauces and puree are said to help lower

urinary tract symptoms (BPH) and may have anticancer properties.

Tomato consumption might be beneficial for reducing cardiovascular

risk associated with type 2 diabetes.

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