G y n o e c i o u s a n d p a r t h e n o c a r p i c c u c u m b e r b r e e d i n g

Mahesh DK, Sr. Breeder,

Rasi hyveg Pvt Ltd. Bangalore

INTRODUC TION Cucumber (Cucumis sat ivus L . ) belongs to fami ly Cucurbitaceae, which d istr ibuted throughout the warmer par ts of the wor ld (Gopala k r ishnan, 2007) . This i s commercia l ly grown a l l over the wor ld in open f ie lds and smal l gardens, even under polyhouses or g lasshouses. Cucumber f rui t i s charac ter ized by low energy, h igh f iber and high water containing vegetable. I ts immature f rui ts are k nown as good appet izer to have cool ing ef fec t . Cucumber is a lso a good source of Vi tamin B and C, carbohydrates, ca lc ium and phosphorus ( Yawalk ar, 1985) . Cucumber i s both a leading commercia l crop Exploitat ion of Gynoecious L ines in Cucumber (Cucumis Sat ivus L . ) for Heterosis Breeding.

Hybrid varieties of cucumber are predominantly used in the production system of many developed and developing countries. The proportion of hybrid varieties is continuously increasing and thus, gynoecious hybrids for open field cultivation and parthenocarpic cucumbers for polyhouse culltivation are important for commercial cultivation.Sex inheritance plays an important role in cucumber hybrid breeding. Several researchers have worked on sex expression of cucumbers and reported that it was genetically determined but could be modified by growth substance application and also environmental factors (Krishnamoorthy, 1975; Lower and Edwards, 1986; Kalloo, 1988). Considering the above factors many combinations of hybrid seed production have been proposed and recommended using gynoecious parents. Despite of all efforts, sex expression variation of commercial hybrids is still a problem in cucumber cultivation (Lower and Edwards, 1986).At present, interesting in stabilizing the gynoecious character and development of stable parthenocarpic & gynoecious inbred parents have been intensified and become a common goal of numerous hybrid breeding programs. Therefore this study was conducted with the following objectives.

a) Breeding parthenocarpic cucumber lines and to develop F1 hybrids adapted to green-house/plastic house cultivation. b) Understand and familiarize breeding Gynoecious cucumber lines and F1 hybrids suitable for open field condition

M ajor Types/S egments of

Cucumbers for breeding

Slic ing cucumber

Pick l ing cucumber B eit Alpha

Sl ic ing cucumber & traits of interest

Plant: Very strong, high branching & longevity Fruit type: Mottle green, white with light green tinge & dark green colour with cylindrical uniform fruits Quality: High keeping quality, transportability, hallow & bitter free

Sex type: Gynoecious, Predominantly female & monoecious types

Parthenocarpic bearing habit

Disease resistance: DM, PM, GSB, CMV & ZyMV

Pick l ing cucumber & traits of interest

Plant: Very strong, less branching & high plant longevity

Fruit type: Mottle green to dark green & glossy green colour with cylindrical uniform fruits, intermediate cluster bearing type

* Market potential

* Types / segments to work on

* Clearly defined objective/ market requirment

* Germplasm base

* Traits of inheritance

* Application of breeding methods with respect to traits of improvement

* Breeding and testing locations etc

Cucumber breeder should

have following knowledge

Slicing cucumber & traits of interest

Quality: Crispy taste, processing quality, hallow & bitter free

Sex type: Gynoecious & predominantly female types

Parthenocarpic or Non parthenocarpic bearing habit Disease resistance: DM, PM, GSB, CMV & ZyMV

Beit alpha cucumber & traits of interest

Plant: Very strong, medium branching & high plant longevity Fruit type: Dark green to glossy green colour with cylindrical uniform fruits, intermediate cluster bearing type Quality: Good keeping qlty & transportability, hallow & bitter free

Sex type: Gynoecious type

Parthenocarpic bearing habit

Disease resistance: DM, PM, GSB, CMV & ZyMV

Conventional Breeding methods

Routine pedigree breeding

Routine back cross breeding

Use of sex inheritance & chemicals in breeding

Use of MAS in line development

Use of DH tech in line development

Cucumber gynoecious line development

Gynoecious cucumber

Breeding for higher yields is an important objective of cucumber breeding programmes (Wehner, 1987). Yield of cucumber can be improved through breed-ing to develop resistance against pest-diseases (Peterson, 1975); improvement in cultural practices (Cargill et al., 1975); qualitative traits improvements like gynoecious sex expres-sion, colour of fruit and yield (Wehner, 1987) or development of high yielding varieties or hybrids. Moreover, cucumber crop is predomi-nantly monoceious in nature but gynoecious sex form has also been reported (Pati et al., 2015) which facilitates hybridization by reduc-ing labour cost for crossing. The gynoecious hybrid cultivars often bear a high proportion of female flowers, resulting in earliness, good yield and give many fruits in a single harvest. Exploitation of Gynoecious Lines in Cucumber (Cucumis Sativus L.) for Heterosis Breeding.

Flowers Male Staminate

Female Staminate

G enetics of sex expression:

Acr acr

A or a A a

M: Gynoecious Monoecious Androecious

m: Hermaphrodi te Andromonoe -

ciousAndroecious

Sex expression is greatly influenced by environmental factors like nutrition, day length, light intensity &

stress factors

Gyno plant grown

M ale f lower appeared in Gyno plant

S elfed fruit Rever t back to gyno plant

Gynoecious f ruit sett ing

Pedigree Breeding

% Homozy-gosity

GenerationCycles YearsGeneration

50

75

87.5

93.75

96.875

F2

F1

F3

F4

F5

F6

S eason -1 DC

F2

F3

F4

F5

F6

S eason -2

Season -3

S eason -1

Season -1

Season -1

Year1

Year2

Populat ion s ize

Pl No. to selectPlant No. to growGeneration

10-20

20-30

BulkF1

F2

F3

F4

F5

F6

200-300

50-100

50-100

30-50

15-20

10-15

8-10

5-8

5-8

Procedure to develop gynoecious cucumber

inbreds

S elec t best Gyno F1 or DCF1

or ?

Grow F2 100-200 Populat ion, ( i t segregates to Gyno, M ono, PF, Andro. . etc) S elec t gyno plants at 3-5 leaves stage, tag them, spray

GA3 than self

Grow ear ly generat ion mater ia l /populat ion at d i fferent tem-perature and day length to conf i rm stable gynoecious nature

Simi lar ly grow F3, F4 , F5 & so on, depends on background of or ig in i t wi l l get f ix at d i f -ferent genera-t ion (F4 to F8)

DOUBLE CROSS ME THOD for Gynoecious LDP

Gynoecious X Fruit uniformit y Plant longevit y X DMR

(L ine -1) (L ine -2) (L ine -3) (L ine -4)

F1 X F1

No. of generations wi l l be cut shor ted i f

DH technology is avai lbale

DH (Andro or Gynogenesis

Progenies of doubled chromosomes

Check & screen for Gynoecious, Par thenocarpic &

CMV resist .

S elec t gyno plant with other desirable traits

DCF1

P yhtopathology scoring at ever y generation

S elec t gyno plant with other desirable traits at ever y

generation

DCF2

IPS upto F6-F8

Colchicine

BACK CROSS ME THOD (Gynoecious, par thenocarpic & CMV resist . )

Gynoecious & par thenocarpic

CMV resist

(L ine -1) (L ine -2)

(L ine -3)

F1

X

X (Line -1)

BC1F1

BC1F2

S creening for resistance

BC2, BC3, BC4, BC5F2,F3

Final ly l ine with Gynoecious & Par thenocarpic with CMV resistance

BACK CROSS ME THOD (Gynoecious, par thenocarpic & CMVR)

CMV resist

(L ine -1) (L ine -2)X

F1

No. of generations wi l l be cut shor ted

i f DH technology is avai lbale

DH (Andro or Gynogenesis

Progenies of doubled chromosomes

Applicat ion of molecular markers to speed up programme

Check & screen for Gynoecious, Par thenocarpic &

CMV resist .

Final ly, The l ine with Gynoecious & Par thenocarpic with CMV resistance

Colchicine

Gynoecious & par thenocarpic

(L ine -1)X

BC1F1

BC1F2

S creening for resistance

BC2, BC3, BC4, BC5F2,F3

M olecular M arkers L inked to Gynoecious Loci

Based on different ecological type materials of cucumber, F1, F2, BC1 and BC2 population were constructed, and the inheritance law of sex was study; RAPD and AFLP markers linked to gynoe-cious loci were attained, these markeres could be utilized for marker assist selecting (MAS) of cucum-ber gynoecious lines.

Use of DH tech in l ine development

Gynoecious

Culture of unpollinated ovaries and ovules rep resent an alternative for the production of haploid plants in species for which anther culture has failed

Not used as much as androgenic methods: Problems in dissection of unfertilized ovules/ ovaries

Successful in Onion, melon, cucumber and sugar beet

Homoz ygous frequenc y

X X

F 1

F 2

F 8

F 7

F 6

F 5

F 4

F 3

F 1

Frequenc y of homoz ygous

0%

50%

75%

87.5%

93.75%

96.88% 98.44%

99.22%

DH l ines100% homoz ygous

Melanie Caffe - 2015, Wheat Double haploid PPT

M ain features of DH: Double haploids are completely homozygous & homogeneous population, hence is highly uniform

DH can be produced both in auto and allogamous species

It’s a rapid method of producing pure lines from heterozygous parents in one generation, conventional takes 3-5 years

DH helps fixation of hybrid vigour or heterosis in hozygous lines. Example: genotypes; AAbb X aaBB Haploid ; AB AB genotye fixed as DH ; AABB

Growing Condit ions of Do -nor Plants

Should be grown under good conditions without stress Must be healthy and vigorous

location, season, soil and water quality is important, esp. if plant material is grown in GH/field

Pesticides/insecticides/fungicides can also cause stress or reduction in embryogenesis!

Improperly controlled growth of donor plants could lead to inconsistent DH plant production efficiencies

Gynogenesis (Female G amete culture)

Donor plant growth O var y culture

Embr yogenesisRooting

Ploidy analysis &diplodizat ion

Hardening &S elf ing

Obser vations: Qualitative Parameters:

1. Plant vigour (Strong, medium and week)

2. Plant Branching habit : (High, medium, poor)

3. Sex type (Monoecious, Gynoecious , PF, Androecious, Gynomonoecious, Andromonoecious, Gynoandromonoe- cious, Hermaphrodite)

4. Parthenocarpy: Parthenocarpic or non parthenocarpic

5. Fruit colour: (Dark green, Mottle green, White with light green tinge & White)

6. Spine colour on fruit: (white, brown, black, nonspiny)

7. Fruit shape: (Cylindrical, tapering end, elliptical, globular round)

8. Fruit Bitterness: (free, little, severe)

9. Hollowness / Cavity:free, little, severe)

Obser vations:

Qualitative Parameters:

1. Days to 50% female flower after planting

2. Days to first harvest after planting

3. Length & Diameter (Cm)

4. Yield (Kg/plant)

Disease Interpretation:

1. Downy mildew incidence score (1-9 scale, 1=immune 3 = high resistance 5=intermediate 7= susceptible)

2. Powdery mildew

3. Cucumber mosaic virus (CMV)/ZYMV/PRSV (Based on prevalence)

4. Gummy stem blight (GSB)

Cucumber gyno & par the -nocarpic l ine development

breeding

Par thenocarpic cucumber futures:

The tendency to produce parthenocar- pic fruit in response to controlled variations in photo-period, temperature and nutrient uptake differed according to variety Must be healthy and vigorous

Parthenocarpic variety must be gynoe- cious and solitary to multi-pistillate flowering habit

Tendency to set fruit without pollination will have no seed in fruit and must have seed with pollination.

Usually cultivated in controlled condition , its ability to bear more number of fruits per plant but needs high management

Its very succulent and susceptible to pest, disease and harsh weather.

Par thenocarpic cucumber plant

Multi -pist i l late f lower

Procedure to develop par thenocarpic cucumber inbreds

Case -I Case - I I

Par thenocarpic F1Par thenocarpic F1 X

Nonpar thenocarpic F1

Grow F2 200-300 Population in net house or polyhouse (divide of pollinators), Select gynoecious

plant with good fruit setting

F3 100-200 plants, F4 50 plants and so on

Grow F5- F6 plants at d i f ferent temperature and day length to conf i rm stable gynoecious

& Par thenocarpic t ype

Grow F2 300-400 Populat ion at control condit ion. Selec t gyno with good f ruit sett ing with out pol l ina-t ion, i t wi l l be cont inued t i l l atta in

pur i t y

Simi lar ly i t wi l l be cont inued for any k ind of populat ion, i f i t i s

having par thenocarpic or gyno gene

S ome Relat ionships of S eed Produc tion with Par thenocarpy

and Relat ive Humidit y in the Cucumber

Nick E. Fanourakis and Eva E. Tzifaki

Points to keep in mind during selec t ion

CUCUMBER SWOT ANALYSIS

Parthenocarpic plant should be gynoecious in nature

Select plant preferably multi-pistillate type

To induce male flower spray GA3 200ppm (3-4 spray at 2-3 true leaves stage) or AgNO3 400ppm (1-2 spray)

Look for early flowering and high fruit setting plants

Good fruit shape, desirable fruit colour and disease resistant plants (DM, PM, CMV, ZyMV & so on) to be selected

Also select plants bearing fruits free from bitter and hollowness

An important advantage of the cucumber plant that makes it suitable for breeding and genetic studies is its ability to produce many seeds in each pollinated fruit. A mature, hand-pollinated fruit containing more than 150 seeds is not rare. However, with parthenocarpic plants the situation is differ- ent. We have observed that the strong parthe- nocarpic beit alpha type produce generally fewer seeds per pollinated fruit than the non- parthenocarpic. Since commercial seeds of parthenocarpic cultivars are produced by hand pollination, seed cost is dependent on the number of seeds produced per pollination

Strongly parthenocarpic cucumber plants produced much fewer seeds than the non- parthenocarpic. However, wide variation was observed within lines. Cross-pollination of the parthenocarpic flowers did not always provide more seeds than self-pollination. The increase of RH during pollination could affect positively the number of seeds per fruit

STRENGTH

Even though narrow genetic diversity exis- tence in cucumber, we able to maintain maximum diversity of germplasm to breed for all major segments

Use of multi-locations for germplasm & hybrid evaluation for wider adoptability

Strong and Unique cucumber hybrids made easy penetration and establish well in the market in short span of time

Active & kind support from PD & sales team to promote hybrids fast in the market

Systematic, well experienced & dedicated work force in the breeding programme

Best research infrastructure facilities & well established phytopathological team

Limited availability of germplasm for stable fruit colour, multi-pistillate flower, resistance to DM, CMV, GSB

Lack of availability of hybrids for wider cultivation ie throughout the country and season

Limited availability of hybrids for processing (Pickling) type and export (Beit alpha)

Difficult to include number of key traits like Bitter free, hallow free, stable fruit colour, DM and CMV resistance in single hybrid.

OPPORTUNITY

India is richest germplasm reservoir, there is good scope for exploiting the potentiality

In India, still 75 % of cucumber OP varieties exists, It is very good opportunity to convert OP to hybrid market.

Majority of cucumber hybrids sells in India are imported, so we have good scope to breed and develop hybrids indigenously

WEAKNESS

Development of hybrids for stable fruit colour, wider adaptable and resistance to DM & CMV is an opportunity

Development of hybrid for poly house cultivation, as its area is growing.

Use of DH technology to fast track line development program.

References

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for yield attributes in cucumber (Cucumis sativus L.).

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99−108.

Dhillon, N.P.S., 2004. Variation and genetics of tolerance to cull

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Hanchinamani, C.N., Patil, M.G., 2009. Heterosis in cucumber

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Saikia, J., Shadique, A., Bora, G.C., 1995. Genetic studies in cucumber:

2. Heritability and genetic advance of yield components. Haryana

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110−115.

Yadav, J.R., Singh, S.P., Singh, N., Singh, P.B., 2008. Heterosis in

cucumber (Cucumis sativus L.). Progressive Research 3(1), 87−88.

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