male sterilitysystem in vegetables

Male sterility and its utilization in vegetable

improvement

Name of the Student : Mr. HEMANT GHEMERAY

ID No. : UHS14PGM537

Degree Programme and Subject : M.Sc. (Hort.) Dept. of Vegetable Sciences

College : College of Horticulture, Bengaluru.

02/05/2023

What is Male Sterility ?

COH Bengaluru2

Definition : Inability of flowering plants to produce functional pollen. Male sterility is agronomically important for the hybrid seed production.

•Onion crop provides one of the rare examples of very early recognition of male sterility cultivar Italian Red (Jones and Emsweller 1936)

•Its inheritance and use in hybrid seed production (Jonesand Clarke 1943).

•Since then male sterility is reported in fairly large number of crops including vegetables.

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Manifestation of Male sterility

1. Mitochondrial mutation : mutation in mitochondrial bodies (mt DNA) (Shrivastva & Sarkssian, 1969)

2. Barrier of tapetal layer : delayed degeneration of tapetal cells that block the availability of nutrient to microspore (Polowick & Sawhney,1995)

3. Improper timing of callase activity : callase is an enzyme required for breakdown of the callose that surrounds the pollen mother cells, helps in release of pollen ; early or delayed callase activity lead to sterility.(Pritchard & Hutton, 1972; Gottshalk & Kaul, 1974)

4. Role of Esterase : Esterase isozymes play role in the hydrolysis of Sporopollenin, the polymer required for pollen formation. Decreased activity of esterase in male sterile plant has been obeserved in tomato (Bhadula and Sawhney,1987) and in radish (Zhon and Zhang, 1994)

5. Absence or malformation of male organs (stamens) in bisexual flowers: Failure to

develop normal microsporogenous tissue- anther.

6. Abnormal microsporogenesis--deformed or inviable pollen.


Significance of male sterility

• Genetic emasculation of plants.

• Economic & quality hybrid seed production.

• Larger quantity of hybrid seeds.

• As tester genotypes for assessing the combining ability.

Flower of male-fertile onionFlower of male-sterile onion


Classification of Male sterility

On phenotypic basis1. Sporogenous male sterility (eg dry/sticky pollen)2. Structural male sterility (eg exerted stigma, stamenless filower in L.

hirsutum)3. Functional male sterility (failure of anther dehiscence; eg tomato & brinjal)

On non genetic basis4. Chemical male sterility5. Physiological male sterility6. Ecological male sterility

On genetic basis (spontaneous or induced)7. Genetic male sterility

i) Temperature sensitive genic male steriltyii) Photoperiod sensitive genic male steriltyiii) Transgenic male sterilty

2. Cytoplasmic male sterility3. Cytoplasmic genetic male sterility

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Genic Male Sterility (GMS) or Nuclear Male Sterility GMS has been reported in about 175 plant species (Kaul 1988) including important

vegetable crops

Salient points• Usually recessive & monogenic• GMS does not have any undesirable agronomic characters

Limitations of GMS• Less Stable to temperature and photoperiod • 50% of the fertile plants to be removed from the field

Availability of marker gene- closely linked with ms gene

Origin of GMS

Spontaneous mutation

Mutation by ionizing radiation. etc

6


Maintenance of GMS

7


Use GMS for hybrid development

LINE A X LINE C Male sterile Male fertile msms MsMs

COMMERCIAL HYBRID Msms (AXC) (All male fertile)

8

Crops Gene Commercially utilized Variety

Tomato Single recessive gene ps-2 gene -Chilli Single recessive gene ms-12 & ms-3 gene CH-1, CH-3

Muskmelon Single recessive gene ms-1 gene Punjab hybrid-1

Male-sterility through genetic engineering

Many transgenes produce genetic male sterility observed in tobacco, brassica spp. tomato, cauliflower, etc.

If transgenes are utilized for hybrid seed production required effective fertility restorer system. eg. Barnase/Barstar - Barnase/Barstar – transgenic tobacco complete male sterile

Vegetable crops- tomato, Cauliflower.

The barnase-barstar male sterility-fertility restoration system was identified in Cauliflower and Tomato ( Banga and Raman 1998)Cell cytotoxicity


Determined by the cytoplasm

It is the result of mutation in the mitochondrial genome (mt-DNA)

CMS easily transferable trait n Most CMS associated genes are chimeric mitochondrial sequences

(Schnable and Wise 1998)

Advantages of CMS• Highly stable and not influenced by environmental conditions

Limitations of CMS

• Not use where seed is the economic product

• CMS line has inferior agronomic performance10

Cytoplasmic male sterility (CMS) systems



Cytoplasmic genetic male sterility

Male sterility arises due to interaction of nuclear gene(s) conditioning sterility with sterile cytoplasm

RR gene with F cytoplasm

(Fertile; R – line)

Genotypes of CGMS line

RR gene with S cytoplasm

(Fertile; R – line)Rr gene with F cytoplasm

(Fertile)

msms F RR

msms F Rr

msms S RR

msms S Rr

msms F rr

msms S rr

Rr gene with S cytoplasm (Fertile)

rr gene with F cytoplasm (Fertile; B – line)

rr gene with S cytoplasm (Sterile; A – line)


Breeding Strategies Using CGMS lines In Hybridization

100% sterile and stable under diverse condition

Unstable during growing season

Mixture of sterile and fertile plants

100% sterile in some environ. & fertile in other

100% fertile and stable under all environment

If line x tester

Indicates B line (Maintainer line)

Indicates temperature and humidity effect

Indicates R line (Restorer line)

Related to climate(temp. and humidity)

Indicates line is hetero-genous at rf1 locus

Outcome

Conversion programme

Benefit of Seed production

Purification via single plant selection

Hybrid development programme

Should be Rejected

Breeding Strategy


Cytoplasmic genetic male sterility(CGMS) in vegetables crops

Crops Gene Commercially utilized Variety

Chilli Single recessive gene ms-2

Arka Meghana, Arka Swetha, Arka Harita, Kashi Surkh

Onion Single recessive gene - Arka Kirtiman, Arka

Lalima

Carrot Single recessive gene - Pusa Nayanjyothi,

Pusa Vasuda

14


Detection of MS System

By progeny performance or crossing with a few normal (fertile) genotype

Trend I – All the progenies in all the rows may be sterile : CMS

Trend II – Some rows may consist of all fertile plants and some rows sterile & fertile plants may occur in 1 : 1 ratio : GMS

Trend III – Some rows may have all fertile plants, some all sterile plants & some have fertile and sterile plants in 1 : 1 ratio : CGMS


GMS based hybrids: CH-1 (MS 12 x Ludhiana long sel.)CH-3 (MS 12 x S-2530)

Hybrids Identified through AICRP-VC CCH-2 (A1 x Pusa Jwala) andCCH-3 (KA-2 x RPBC-473) ARCH-228, Meghna

TOMATO Ludhiana ms33 IPAms2 IPAps2 L 3841ps2 NS 101ps2 San Pedrops2 UC 82-Bms 1036

ms 45ms 1547

CHILLIAnandCCA 4261CCA 4759CCA 4758 LudhianaCCA 4261

ONIONBangaloreMs1Ms2ms3

Male sterile genotypes available in India

S. No. Name of chilli hybrid Source

1 CH 1 (GMS based) PAU, Ludhiana

2 CH 3 (GMS based) PAU, Ludhiana

3 Arka Meghana (CGMS based) IIHR, Bangalore

4 Arka Sweta (CGMS based) IIHR, Bangalore

5 Arka Harita (CGMS based) IIHR, Bangalore

6 Arka Khyati (CGMS based) IIHR, Bangalore

7 CCH 2 (CGMS based) IIVR, Varanasi

Steps in development of male sterile line1.Morphological and molecular evaluation of male sterility system.2. Studies on blossom biology on floral morphology of male sterile and fertile flowers.3. Transfer of male sterility into different genetic backgrounds to identify corresponding maintainer & restorer lines/ pollen parents. 4.Studies on microsporogenesis and megasporogenesis of male sterile and male fertile lines. 5.Development mapping population (parents, F1, F2 ,BC1, BC2 progenies) for genetic studies.

6.Identification of molecular markers7. Studies on reproductive biology and identify causes of male sterility (CMS,CGMS& GMS system)). 8.. Use of diagnostic PCR kit to identify sterile, maintainer and restorer lines.

9. Development of stable male sterile lines, maintainers, restorer and male parental lines to develop uniform efficient and durable F1hybrids.


Male sterility in selected vegetables

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Mutant Description Inheritance Governing by single recessive

gene

Stamenless Stamens absent Monogenic recessive

sl

Positional sterility Stigma exerted Monogenic recessive

ps

Pollen sterility Pollen abortive Monogenic recessive

ms series

Functional sterility Anthers do not dehisce

Monogenic recessive

ps-2

Table 6: Different male sterile mutants in tomato.


First report of MS within progenies of an onion cultivar Italian Red (Jones & Emeweller, 1936); Male sterility controlled by male sterile cytoplasm & recessive nuclear gene (Jones & Clarke, 1943)

3 types of Cytoplasm1. S – cytoplasm

- anther morphology is normal but at anthesis these are green, small & indehiscent

2. T - cytoplasm (Berninger in Jaune Paille des Vertus(1965))- anther morphology is disrupted. (Kaul, 1988)

Onion

Bennekam, 1979


Emasculation avoided (STEP I)

Male sterile flower

Covering entire stigma with pollen (STEP II)

USE OF CGMS SYSTEM IN HYBRID SEED PRODUCTION IN CHILLI

Type of male sterility: CMS & CGMS

Present status: AB& R lines have been developed

(CGMS); AB&C lines( CMS) to be developed and commercializedIncorporation of Anthracnose, phytophthora blight resistance & pungency with male sterility & development of F1 hybrids

CHILLI

02/05/2023 21

GMS : Due to shrivelled, brown & non exerted

antherCMS & CGMS : 3 types of CMS1. Petaloid type

- anther transformed into petal or petal like structure, unable to produce functional pollen

2. Brown anther type- present in all orange type cultivars- deformed, brown coloured anther without functional pollen

3. Gum type- derived from cross with D. carota var gumifera- total reduction of anthers & petals

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Carrot

a) Normal (N-cytoplasm, restored CMS plants)b) Brown anther CMS (Sa)c) Petaloid CMS (Sp)


Type of male sterility: GMS (Inductive)

Present status: AC lines have been developed and commercialized

Incorporation of YVMS resistance with male sterility & development of F1 hybrids

Okra


GMS lines in okra

Geneic male Sterile Male fertile

GMS line can be maintained by sibbing


Cole vegetables

Transfer of Orgura cytoplasm of Raphanus to:

• broccoli (McCollum, 1981);

• Cauliflower (Hoser, Kranse & Antosik, 1987);

• Brussels sprout (Bannerot et al,1974) and in Cabbage (McCollum, 1988).

• But seedling of all these CMS line developed chlorosis in seedling & young leaves lead to delayed maturity.

• Transfer of sterile ‘Anand cytoplasm’ from B. rapa (originally derived from wild spp B. tounetortii) to - B. olearcea trough protoplast fusion ( Cardi & Earle, 1997)


IIHR CFMS-1

ogura ms

IIHRRGMS-2

IIHRRGMS-2 medium long fruits

Fertile pollen

Rudimentary male flowers

Fertile flower spikes

Male Sterile

Male Sterile buds

Male Fertile

Sterile pollen

Ridge gourd

Type of male sterility: CGMS & GMS


Development of male sterile lines of tomato and assessment of their utility in hybrid

development

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Case -1


Material and methods

• ms33 IPA• ms2IPA• ps2 L 3841• ps2 NS 101• ps2 SanPedro• ps2 UC 82-B1.•

OBJECTIVE:

1.Transfer of trait(male sterility) through back cross2. Evaluation of new stocks3. Assessment of labour needs for hybrid seed production using new stocks


Table 1. Fruit characteristics of tomato male sterile lines

S. No.

Genotype Sterility No. Of

LoculesPericarp thickness

(mm)TSS (%)

Fruit weight

(g)

1 ms33 IPA Pollen Abortive 2.33 6.33 4.60 59.00

2 ms2IPA Pollen Abortive 2.00 6.33 4.75 62.33

3 ps2 L 3841 Functional 4.66 6.00 4.16 61.334 ps2 NS 101 Functional 3.00 6.00 4.60 59.33

5 ps2 SanPedro Functional 3.83 6.66 4.80 112.66

6 ps2 UC 82-B Functional 4.10 6.30 4.63 67.00

29

Dhaliwal and Cheema., 2008



Table 2. Time (minutes) required for crossing 50 flower buds on male fertile ‘Ms33IPA’ (MF) and male sterile ‘ms33IPA’ (MS) plants in tomato

Worker

Activity

Emasculation Pollination on MFEmasculation & Pollination on MF

Pollination on MS Time saved in MS over MF %

1 22.0 44.0 66.0 37.7 42.9

2 26.1 34.9 61.0 26.3 56.5

3 38.7 45.1 83.8 33.3 60.3

4 37.3 43.8 81.1 24.2 54.7

5 32.8 41.1 73.9 32.7 55.8

Mean 30.7 41.7 71.9 32.8 54.4

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Dhaliwal and Cheema, 20081 2 3 4 5 Mean

0102030405060708090

Activity Emasculation Activity Pollination on MF Activity Emasculation & Pollination on MF E Activity Pollination on MSActivity Time saved in MS over MF %


Development and utilization of one new cytoplasmic male sterile line of Chinese leaf mustard (Brassica juncea var.

rugosa Bailey)

Case 2


Materials and methods• hau CMS (donor parent 00-6-102A). • Xuelihong 0912B ( receptor parent leaf mustard)• Novel cytoplasmic male sterility (CMS) designated as hau

CMS (00-6-102A) was identified in Brassica juncea previously. • In present study, the hau CMS was transferred to leaf

mustard (B. juncea var. rugosa Bailey) for harvesting vegetative mass by hybridization

F1BC8

00-6-102A( hau CMS) x 0912B sterile hybrid x 0912B (backcrossed)

line 0912A was obtained


Table 1: Biological characteristics of hau CMS line 0912A and maintainer line 0912B in leaf mustard

Traits 0912A 0912B 0912A-0912BPlant weight (g) 959.81 965.35 −5.54

Plant height (cm) 34.17 37.70 −3.53*

Canopy area (cm2 ) 1917.64 1950.84 −33.2

Leaf length (cm) 36.39 37.05 −0.66

Leaf width (cm) 12.14 12.00 0.14

Petiole length (cm) 4.04 4.38 −0.34

Petiole width (cm) 1.57 1.62 −0.05

Tiller number 16.28 16.33 −0.05

Rosette leaf number 166.11 160.06 6.05

34Wan et al., 2014


Table 2: Leaf morphology of Brassica juncea 00-6-102A, hau CMS line 0912A and maintainer line 0912B in leaf mustard.

Material Leaf colour

Leaf shape

Leaf edge Leaf crack Leaf

surfaceShine

surface

00-6-102A Green Obovate

Shallow saw

toothPinnatified Slight

shrinkage No

0912A Deep green

Long Obovate

Saw tooth Pinnatified Smooth Yes

0912B Deep green

Long Obovate

Saw tooth Pinnatified smooth yes

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Wan et al., 2014


Fig. 1. Morphological traits (A) Brassica juncea 00-6-102A; (B) leaf mustard CMS line 0912A. (C) Leaf mustard maintainer line 0912B; (D) leaf mustard CMS line 0912A; (E) leaf mustard maintainer line 0912B.

36


Table 3: The identification of the ‘sterility degree’ and ‘sterility rate’ of hau CMS line 0912A in leaf mustard

Time Place Plants Sterile plants Flowers Sterility

ratio SeedsSterility degree

(%)

2010.3 Wuhan 90 90 2700 100 0 100

2010.7 Lanzhou 90 90 2700 100 0 100

2011.3 Wuhan 90 90 2700 100 0 100

2011.7 Lanzhou 90 90 2700 100 0 100

37Wan et al., 2014

Plants

Sterile

plants

Flowers

Sterili

ty rati

o See

ds

Sterili

ty degr

ee (%

) 0

500

1000

1500

2000

2500

3000

2010.3 Wuhan

2010.7 Lanzhou

2011.3 Wuhan

2011.7 Lanzhou


Table 4: The comparison of flowering and seeding of hau CMS line 0912A and maintainer line 0912B in leaf mustard

Lines Corolla expansion

Petal length

Petal width

Style diameter

Style length

Stamen length

Seeds per

silique

0912A 7.47 0.63 024 0.09 0.63 0.47 13.13

0912B 12.19 0.84 0.37 0.09 0.74 0.81 14.20

t 16.61** 9.84** 13.79** 0.5 8.49** 15.08** 1.06

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Wan et al., 2014

02/05/2023

Fig. 2. Flower morphology and the pollen vitality. (A) The flower of hau CMS; (B) the flower of 0912A; (C) the flower of 0912B; (D) pollen vitality of 0912A; (E) and (F) pollen vitality of 0912B.

COH Bengaluru 39


Conclusion • A new CMS line of leaf mustard with high potential in heterosis utilization was

bred and characterized for anther and pollen development. • Researches on cytology, the restorer and maintainer relationship, and

polymorphism of mitochondrial DNA indicated that hau CMS was different from the pol CMS, Shan 2A, ogu CMS, tour CMS, and nap CMS systems.

• hau CMS had no anthers while all the other CMS lines mentioned above formed anthers but were devoid of functional pollen

• Fertility identification for two consecutive years showed that stamen of 0912A aborted completely, with no pollen formed, indicating the successful transfer of hau CMS to 0912A

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Chemical induction of male sterility and Histological studies in Okra (Abelmoschus

esculentus L.)

41

Case 3

Material and methods

Variety : Arka AnamikaChemicals : GA3, Ehtrel, Maleic HydrazideFoliar spray : three. (20, 20+30, 20+30+40)

Concentration : GA3 – 200, 300, 400 ppm. Ethrel – 750, 1000, 1250 ppmMH – 50, 100, 200 ppm.

Plant material


Treatments detail

T1- GA3 @ 200 ppm at 20 DAS

T2- GA3 @ 200 ppm at 20+30 DAS

T3-GA3 @ 200 ppm at 20+30+40 DAS


T5- GA3 @ 300 ppm at 20+30 DAS

T6-GA3 @ 300 ppm at 20+30+40 DAS


T8- GA3 @ 400 ppm at 20+30 DAS

T9- GA3 @ 400 ppm at 20+30+40 DAS

T10- Ethrel @ 750 ppm at 20 DAS

T11- Ethrel @750 ppm at 20+30 DAS

T12- Ethrel @750 ppm at 20+30+40 DAS


T14- Ethrel @ 1000 ppm at 20+30 DAS

T15- Ethrel @ 1000 ppm at 20+30+40 DAS


T17- Ethrel @ 1250 ppm at 20+30 DAS

T18- Ethrel @ 1250 ppm at 20+30+40 DAST19- MH @ 50 ppm

at 20 DAS

T20- MH @ 50 ppm at 20+30 DAS

T21-MH @ 50 ppm at 20+30+40 DAS

T22- MH @ 100 ppm at 20 DAS

T23- MH @ 100 ppm at 20+30 DAS

T24-MH @ 100 ppm at 20+30+40 DAS

T25-MH @ 200 ppm at 20 DAS

T26-MH @ 200 ppm at 20+30 DAS T27-MH @ 200 ppm at 20+30+40 DAST28 - Control (water spray)

43


65.23 90.37

76.50 50.401546.2 1601.9

3.05

21.6764.0745.506.73

14.83

84.3347.37


Treatment

Plant height (cm)

Treatment

Leaf area (cm2)

Treatment

NO. Of branch

es

Treatment

Days to flower

initiation

Treatment

Days to 50%

Flowering

T9 90.37 T28 1601.9 T19 3.05 T9 39.77 T9 42.63

T8 89.87 T1 1538.2 T20 3.00 T8 39.87 T8 42.70

T27 76.50 T18 1382.2 T18 1.45 T27 47.37 T27 50.40

45

Table 1. Effect of application of different gametocides on plant height (cm), leaf area (cm2), number of branches, number of days to flower initiation and days to 50 per cent flowering in okra variety Arka Anamika

Deepak et al., 2007


TPollen

sterility (%)

TOvular sterility

(%)

T

Number of fruits

per plant

T Seed yield per plant

T27 84.33 T27 8.87 T1 6.00 T1 19.60

T18 82.10 T18 14.83 T2 6.00 T2 19.48

T28 9.10 T28 0.00 T28 6.73 T27 21.67

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Table 2: Effect of application of different gametocides on pollen sterility (%), ovular sterility (%), number of fruits per plant and seed yield per plant in okra var. Arka Anamika

Deepak et al., 2007



Conclusion • Spraying of maleic hydrazide (200 ppm) at 20, 30 and 40

DAS was found to be better for higher pollen sterility (84.33%) and also lower ovular sterility (8.87%) followed by GA3 spray.

• Hence, MH can be considered as a safe gemetocide at 200 ppm

48


Development of a codominant CAPS marker linked to the Ms locus controlling fertility restoration in onion (Allium cepa L.)

Case 4


Fig. 1. Morphological characteristics of fertile flowers (A) and fertile anther before (B, left) and after (B, right) dehiscence vs. sterile flowers (C) and anther before (D, left) and after (D, right) dehiscence.

The objective of this study :

To identify molecular markers more tightly linked to the Ms locus.

In addition, it was designed to assess the efficiency of allelic discriminationof newly identified markers and previously reported OPT and PSAO markers and the genetic relationship among those markers was investigated.


MATERIALS AND METHODS

Plant material

Male-fertile line ‘H6’ Male sterile line ‘506L x’red bulb color

A total of 301 plants from F2 and F3 populations were used for a genotyping analysis and a molecular marker assessment.

Isolation of genomic DNA

RAPD analysis 680 random primers used to screen polymorphisms between theparent lines ‘506L’ and ‘H6’ and between the two different DNAbulks from male-fertile and male-sterile F2 plants

yellow bulb color


Sequencing and genome walking The amplified polymorphic fragment excised and purified. The purified PCR fragment was cloned into pCR®4-TOPO vector in TOPO TA Cloning Kit Plasmids were purified with QIAprep Spin Miniprep Kit (Qiagen, Valencia, CA). The sequencing reaction was performed using a BigDye® Terminator v3.1 Cycle Sequencing Kit (Applied Biosystems; Foster City, CA). Once a partial sequence was acquired, DNA walking was performed using a Universal Genome WalkerTM Kit (BD Biosciences, Palo Alto, CA).

CAPS marker analysis To convert the dominant RAPD marker into a codominant marker, both sequences of male-fertile and male-sterile alleles were aligned to identify polymorphic regions. For genotyping of segregating populations, PCR was performed PCR products were digested using AvaII. Digested products were separated on a 1% agarose gel for individualgenotyping


RAPD marker analysis

Fig. 2. (A). A polymorphic band identified from RAPD between male-fertile and male-sterile F2 plants using a random primer OBC14B). Genotype analysis using the CAPS marker ACms.1100 derived from the RAPD marker co-segregated with the restorer-of-fertility locus Ms

680 RAPD markers screened

41 polymorphic bands were identified

But only BC14 primer produced a polymorphic band co -segregating with the fertility in the male fertile bulk DNA & the band was absent in male sterile bulk


Conversion of a RAPD marker to a codominant marker

fig


Conclusion

In this study, the RAPD marker OBC14.1000 was identified .

ACms.1100 marker was developed from the OBC14.1000 marker to convert a dominant marker to a codominant marker.

The genotyping analyses using the OBC14.1000 and ACms.1100 markersdemonstrated that both markers are more reliable than any other markers currently available.

Therefore, these markers would be ideal for the allelic discrimination in marker assisted breeding of onion to predict the genotype of a restorer-of- fertility gene having better efficiency and can be the first step to identify a restorer-of-fertility gene.

Further, these markers will be useful in hybrid onion seed production using CMS.


Development of Genic Male-sterile Watermelon Lines with Delayed-green Seedling Marker

X.P. Zhang, B.B. Rhodes, and W.V. BairdDepartment of Horticulture, Clemson University, Clemson, SC 29634

Case 5


Materials and Methods

Breeding Lines:• G17AB (containing the ms gene.)• Pale90 (line containing the dg gene, was selected for yellow

cotyledons and delayedgreen true leaf)


Crosses between G17AB male sterile plants and delayed-green plants were made


Results and Discussion

ms and dg loci are inherited independently and confirms that the newly ms selected dg mutant is inherited as a single recessive nuclear gene.• All lines (MSDG-1, MSDG-2, were fixed for the dg seedling marker, and each segregated (1 sterile : 1 fertile) for male fertility.• MSDG-1 produces round fruit ,similar to G17AB.•MSDG-2 produces fruit, similar to that of ‘Sugar Baby’.

The two breeding lines, MSDG-1 and MSDG2, will provide valuable germplasm for introducing the ms male sterility and dg delayed green into various genetic backgrounds using backcrossing without labor-intensive manual cross- and self-pollinations • The ms and dg genes can be introduced from lines developed in this study into various genetic backgrounds


• The two breeding lines, MSDG-1 and MSDG2, will provide valuable germplasm for introducing the ms male sterility and dg delayed green into various genetic backgrounds using backcrossing without labor-intensive manual cross- and self-pollinations

Conclusion


Futuree prospects` Identification of new ms line through exploitation of other domesticated and wild

species. Identification of potential restorers through molecular techniques and their use for

development of hybrids

Pollination mechanisms of male sterility in different vegetable crops should be further investigated for effective hybrids seed production.

Development of hybrids with multiple resistance/ tolerance to biotic as well as abiotic stresses by transfer of genes using conventional and biotechnological approaches.

To identify potential markers for genetic purity testing. The hybrid seed production technologies should be generated

Potentiality of transgenic male sterility should be use in vegetable crops.

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02/05/2023 62

• Despite the complex maintenance process and additional labour requirement to remove fertile segregants in hybrid seed production field, production of male sterile based hybrid seeds is more economical than the seeds produced by manual emasculation• The research on male sterility in vegetables is a never ending process due to rapid advancement of molecular advancements• Substantial progress has been made in understanding the mechanism of male sterility in selected vegetable crops techniques and their implementation.

• In fruit bearing vegetables like tomato, brinjal, chilli, muskmelon etc., identification and utilization of functional male sterility are more attractive.

• In India, research on transgenic male sterility system was initiated in selected vegetables

• Our first priority should be utilization of existing and established but unexploited male sterility systems especially in chilli, onion, tomato,

COH Bengaluru

CONCLUSION