CrossTalking Tomato Late Blight

**Tom Wagner** · August 18, 2009

I have found this a hard subject to make simple. But here goes...

Tomato late blight resistance genes are non-allelic

Quote:Non-allelic genes are genes located at different loci on the same
chromosome or on different chromosomes altogether.

The gene, Ph-3, Chromosome 9
Ph-1 (chromosome 7
Ph-2 (chromosome 10).

Reports are that
Quote:WV106
carried a single dominant allele conditioning a high level
of resistance to P. infestans tomato race 0 (T0) (Ph-1)

and that WV700 possessed one or more dominant resistance genes (but is associated with Ph-2)

Quote:Researchers at the AVRDC identified resistance to late blight from Solanum pimpinellifolium L. accession L3708. Segregation data obtained for resistance do not support the hypothesis of single gene control of the full resistance trait, but suggest that more than one gene is involved, and that these genes interact in an epistatic manner. Differential responses were also observed between the resistant CU-R lines and the resistant CLN-R lines, which were independently bred from L3708. RFLP analysis confirmed the Ph-3 gene derived from L3708 is located on chromosome 9.

The meaning of (genes interact in an epistatic manner )
epistatic (not comparable)

1. (genetics) Of or pertaining to epistasis, the interaction between genes.

I have a lot of self doubt about my work with Late Blight resistance. Since I had great results with sinlgle dominance with WV 700 with my particular strain of it for years 2004-2007. But 2008 is a year that needed homozygous Ph-2 and Ph-3 clones. Mountain Magic has heterozygous genes as a hybrid and it did not survive to the end of the infestation process. Only my most homozygous clone (Ph-2 and Ph-3)survived totally. I will be testing some seedlings from the recent hybrid of WV 700 X homozygous Ph-1 and 2 for this fall. The hybrid would be homozygous for Ph-2 but only heterozygous for Ph-1.

The good news is that I am transferring the genes Ph-2 and Ph-2 into a wide variety of clones such as Black Pineapple, Black Prince, Green Sleeves, WV 700, and many, many more. I've got to remind myself to sow a huge compilation of varieties soon.

The kind of work I am doing with require that I do a large extension collaboration. I will be exploring ideas to that effect soon.

Tom Wagner

Frog · October 9, 2009

This is very interesting tom, thanks for posting it.

**Tom Wagner** · October 18, 2009

I am finishing up most of my work shops on tomato and potato breeding/ During each of the many work shops I talk about Late Blight. It seems that everyone in Europe in the seed saving work is interested in my take on the malady.

More about the two months I have been spending in Europe later.

Tom Wagner

GunnarSK · December 9, 2009

Quote:

Originally Posted by Tom Wagner

During each of the many work shops I talk about Late Blight. It seems that everyone in Europe in the seed saving work is interested in my take on the malady. 'More about the two months I have been spending in Europe later.

Tom Wagner

In the countries I know, late blight is percieved more as a potato disease than a tomato one. It is known as "kartoffelskimmel" (potato mold/mildew) in Danish and
"zaraza ziemniaczana" (potato infection) in Polish. I never heard about early blight, and I doubt there exists any single word to denote it in either language.

travis · December 10, 2009

Early Blight in German might be Lästiger Blattfleck. In Dutch, Lastige Bladvlek. In Polish, Pesky Yechrotska.

August 18, 2009	#1
Tom Wagner Crosstalk™ Forum Moderator Join Date: Aug 2006 Location: 8407 18th Ave West 7-203 Everett, Washington 98204 Posts: 1,157	CrossTalking Tomato Late Blight I have found this a hard subject to make simple. But here goes... Tomato late blight resistance genes are non-allelic Quote:Non-allelic genes are genes located at different loci on the same chromosome or on different chromosomes altogether. The gene, Ph-3, Chromosome 9 Ph-1 (chromosome 7 Ph-2 (chromosome 10). Reports are that Quote:WV106 carried a single dominant allele conditioning a high level of resistance to P. infestans tomato race 0 (T0) (Ph-1) and that WV700 possessed one or more dominant resistance genes (but is associated with Ph-2) Quote:Researchers at the AVRDC identified resistance to late blight from Solanum pimpinellifolium L. accession L3708. Segregation data obtained for resistance do not support the hypothesis of single gene control of the full resistance trait, but suggest that more than one gene is involved, and that these genes interact in an epistatic manner. Differential responses were also observed between the resistant CU-R lines and the resistant CLN-R lines, which were independently bred from L3708. RFLP analysis confirmed the Ph-3 gene derived from L3708 is located on chromosome 9. The meaning of (genes interact in an epistatic manner ) epistatic (not comparable) 1. (genetics) Of or pertaining to epistasis, the interaction between genes. I have a lot of self doubt about my work with Late Blight resistance. Since I had great results with sinlgle dominance with WV 700 with my particular strain of it for years 2004-2007. But 2008 is a year that needed homozygous Ph-2 and Ph-3 clones. Mountain Magic has heterozygous genes as a hybrid and it did not survive to the end of the infestation process. Only my most homozygous clone (Ph-2 and Ph-3)survived totally. I will be testing some seedlings from the recent hybrid of WV 700 X homozygous Ph-1 and 2 for this fall. The hybrid would be homozygous for Ph-2 but only heterozygous for Ph-1. The good news is that I am transferring the genes Ph-2 and Ph-2 into a wide variety of clones such as Black Pineapple, Black Prince, Green Sleeves, WV 700, and many, many more. I've got to remind myself to sow a huge compilation of varieties soon. The kind of work I am doing with require that I do a large extension collaboration. I will be exploring ideas to that effect soon. Tom Wagner

October 9, 2009	#2
Frog Tomatovillian™ Join Date: May 2009 Location: Kent, UK Posts: 141	This is very interesting tom, thanks for posting it.

October 18, 2009	#3
Tom Wagner Crosstalk™ Forum Moderator Join Date: Aug 2006 Location: 8407 18th Ave West 7-203 Everett, Washington 98204 Posts: 1,157	I am finishing up most of my work shops on tomato and potato breeding/ During each of the many work shops I talk about Late Blight. It seems that everyone in Europe in the seed saving work is interested in my take on the malady. More about the two months I have been spending in Europe later. Tom Wagner

December 10, 2009	#5
travis Tomatovillian™ Join Date: Jan 2006 Location: Evansville, IN Posts: 2,984	Early Blight in German might be Lästiger Blattfleck. In Dutch, Lastige Bladvlek. In Polish, Pesky Yechrotska.