Gene Pyramiding in Tomato

Speaker : Ms. Rashmi Kumari PhD (2nd Semester)

Reg. No :- D/HORT/005/BAC/2015-16Department of Horticulture

(Vegetable & Floriculture)

BIHAR AGRICULTURAL UNIVERSITY, SABOUR

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What is gene pyramiding ?

Gene pyramiding is defined as a method aimed at assembling multiple desirable

genes from multiple parents into single genotype for specific trait.

Pyramid could be constructed with major gene, minor gene, effective genes,

ineffective genes, race-specific genes, non-race specific genes, or any other types

of host gene that confers resistance.

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Why gene pyramiding?

Enhancing trait performance by combining two or more genes.

Remedy of deficits by introgression of genes from other sources.

Increasing the durability of disease resistance.

Broadening the genetic basis of released cultivars.

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Types of gene pyramiding

Conventional Technique

Serial gene pyramiding : Genes are deployed in same plant one after one

Molecular technique

Simultaneous gene pyramiding : Genes are deployed at a time in a single plant

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(Hospital et al.,2004)

Gene pyramiding scheme cumulating six target genes.

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Different schemes of marker-assisted backcrossing for gene pyramiding

RP- Recurrent parent; DP- Donor parent; BC-Backcross; IRP- Improved recurrent parent. A. Stepwise transfer; B. Simultaneous transfer; C. Simultaneous and stepwise transfer. Joshi and Nayak (2010)

A B C

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EFFICIENCY OF GENE PYRAMIDING

A MAS based gene pyramiding scheme based on a cascading pedigree is less

expensive and requires the smallest cumulated population size of all the schemes. The

average transmission probability is 0.9975.

Gene pyramiding scheme based on the crosses of founding parents the population size

is somewhat higher. The average transmission probability is 0.9967.

(Hospital et al.,2004)

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Effectiveness of marker-assisted backcrossing for gene pyramiding depends upon

Distance between the closest markers and the target gene

Number of target genes to be transferred

Genetic base of the trait

Number of individuals that can be analyzed

Genetic background in which the target gene has to be transferred

Type of molecular marker used

Available technical facilities

(Weeden et al., 1992; Francia et al., 2005) 8

Scientific name : Solanum lycopersicum L. Chromosome no.: 2n = 2X = 24

Origin : India

Tomato

Area, Production & Productivity status

In India : (2nd rank)

Area: 0.882 million hectares

Production: 18.73 million tonnes

Productivity: 21.2 MT/ha.

In Bihar : (9th rank)

Area: 0.047 million hectares

Production: 1.061million tonnes

Productivity: 22.3 Mt/ha. Source: NHB database, 2014 9

Pyramiding for ToLCV and its effect on yield & other associated traits

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ToLCV Resistance Sources

S. habrochaites f. glabratumS. peruvianum

S. peruvianum

S. chilense

Resistant gene sources References

Ty-1 S. chilense Zamir et al., 1994

Ty-2 S. habrochaites f. glabratum Kalloo and Banerjee(1990)

Ty-3 S. chilense Ji et al. (2007)

Ty-4 S. chilense Ji et al.(2009)

Ty-5 S. peruvianum Hutton et al. (2012)

Ty-6 S. chilense Hutton et al. (2012)

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ToLCV Disease Severity Index

DSI =0 No symptoms

DSI=1 Some symptoms at new growing point but only visible from close distance

DSI=2 Symptoms are visible from 2 feet but still localized to new growing points

DSI=3 Symptoms are visible all over the plant

DSI=4 Symptoms are so severe and plant are stunted and stop growing

(Friedmann et al. 1998, Lapidot and Friedmann 2002)12

Pyramiding Ty-2 and Ty-3 for ToLCD

Disease reaction to Tomato leaf curl Bangalore virus (ToLCBV), Tomato leaf curl New Delhi virus (ToLCNDV) and Tomato leaf curl Palampur virus (ToLCPalV) by pyramided lines and tomato lines differing for presence of Ty genes, 60 days post-agroinoculation. Tomato cultivar Punjab Chhuhara is a susceptible control.

Prasanna et al., 201513

Cont……

Prasanna et al., 201514

Response of pyramided lines and tomato lines carrying different Ty genes to three different tomato leaf curl virus species in agro-inoculation tests

DSI: disease severity index as described earlier; DPI: days post-inoculation

Prasanna et al., 201515

Horticultural performance and response of pyramided lines and tomato lines carrying different Ty genes in field traits

Prasanna et al., 2015 16

Parent lines used to make a set of non-reciprocal di-allele crosess

Disease severity index means of F1 hybrids and parental lines scored 5 weeks after inoculation with Tomato yellow leaf curl virus

Vidavski et al. 2008Ten infected plants from each parental line or F1 hybrid were evaluated in each replicate 17

Line/F1 hybrid DSI Average yield kg/plant Yield loss (%)SUSNon-inoculated Inoculated

 4.0

 5.20.04

 99.2

PIMNon-inoculatedInoculated

 3.6

 8.80.9

 89.7

CHILNon-inoculated Inoculated

 2.6

 5.42.0

 62.9

HABNon-inoculated Inoculated

 1.3

 4.31.4

 67.4

72-PERNon-inoculated Inoculated

 1.3

 7.7 3.4

 55.8

Vidavski et al. 2008

TyLCV-induced symptom severity and yield reduction of the different parents and F1 hybrids

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Line/F1 hybrid DSI Average yield kg/plant Yield loss (%)

SUS×PIMNon-inoculated Inoculated

 4.0

 10.1 0.9

 91.1

SUS×CHILNon-inoculated Inoculated

 2.7

 10.21.9

 81.4

SUS×HABNon-inoculated Inoculated

 2.2

 7.7 1.7

 77.9

SUS×72-PERNon-inoculated Inoculated

 3.8

 8.7 2.3

 73.6

PIM×CHILNon-inoculated Inoculated

 1.9

 12.2 2.8

 77.0

Vidavski et al. 2008

Cont……

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Line/F1 hybrid DSI Average yield kg/plant Yield loss (%)

PIM×HABNon-inoculated Inoculated

 1.6

 11.12.7

 75.7

PIM×72-PERNon-inoculated Inoculated

 2.2

 11.03.8

 65.5

CHIL×HABNon-inoculated Inoculated

 2.6

 7.33.0

 58.9

CHIL×72-PERNon-inoculated Inoculated

 2.0

 6.92.4

 65.2

HAB×72-PERNon-inoculated Inoculated

 0.9

 9.35.0

 46.2

Vidavski et al. 2008

Cont……

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Pyramiding for drought and its

effect on yield & quality

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Pyramiding of S. pennellii Introgressions

Gur and Zamir (2004)

Effect on yield (fruit weight kg/m2)

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Gur and Zamir (2004)

Effect on TSS (%)

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Gur and Zamir (2004)

Effect on TSS and yield (Brix/g of fruit)

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Pyramiding for quality traits and its effect on yield

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S. pennellii introgression lines have been found to be powerful

material for dissecting plant yield and fruit quality (Gur and Zamir

2004; Rousseaux et al. 2005; Stevens et al.2007).

S. pennellii introgression lines also used for enhacning carotenoids,

fruit weight and composition in sugars and acids, antioxidant

compounds, volatile aromas and various metabolites (Lippman et al.

2007).

Introgressions originating from S. pennellii were introduced into lines

of processing tomato, and the resulting hybrid AB2 is presently a

leading variety in California (http://www.ptab.org/ranking9.htm),

which is the largest producer of processing tomatoes in the world.

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Pyramiding for fruit quality traits in tomato

Ascorbic acid, total phenols and °Bx content in red-ripe fruit from the tomato IL7-3, IL12-4, ILH7-3, ILH12-4, ILH7-3+12-4, IL7-3+12-4 genotypes and the parental line M82. Sacco et al.,2013

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Effect of gene pyramiding on yield

Sacco et al.,2013 28

Gene pyramiding in tomato is mainly done for TyLCV, drought and quality characters.

The pyramided tomato lines developed can be important genetic resources for sustainable tomato production

in areas affected by tomato leaf curl virus disease.

Marker-assisted selection for TyLCV resistance genes offers many advantages, including the possibility of

eliminating susceptible plants in a segregating population before transplanting, and the identification of

plants homozygous for Ty-2 and Ty-3 or other combinations in early generations so that selection in later

generations could focus on horticultural, fruit quality or nutritional traits.

The combination of multiple wild introgressions is likely to also bring negative horticultural traits caused by

linked genes. Therefore it would be useful to generate and use minimal introgression lines for pyramiding of

different specific genes.

Conclusion

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Thank you…

…For your kind attention30