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Definitions

Definitions. Programmed cell Death

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Definitions

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  1. Definitions Programmed cell Death Programmed cell-death (PCD) is death of a cell in any form, mediated by an intracellular program. In contrast to necrosis, which is a form of cell-death that results from acute tissue injury. PCD is carried out in a regulated process which generally confers advantage during an organism's life-cycle. P Balint-Kurti QDR lecture

  2. Balancing selection refers to forms of natural selection which work to maintain genetic polymorphisms (or multiple alleles) within a population. Balancing selection is in contrast to directional selection which favor a single allele. • Diversifying selection, is a descriptive term used to describe changes in population genetics that simultaneously favor individuals at both extremes of the distribution. P Balint-Kurti QDR lecture

  3. Quantitative Disease Resistance • Most disease resistance used in maize is quantitative rather than qualitative • Arguably , this applies generally, or it will in the future. • Very little is known about physiological or molecular genetic basis of QDR P Balint-Kurti QDR lecture

  4. P Balint-Kurti QDR lecture

  5. Host-pathogen interactions: individual-level SUSCEPTIBLE RESISTANT SUSCEPTIBLE RESISTANT SUSCEPTIBLE RESISTANT SUSCEPTIBLE RESISTANT Host-pathogen interactions: population-level Host genotype Pathogen genotype Randy Wisser P Balint-Kurti QDR lecture

  6. Quantitative trait loci (QTL) control quantitative traits P Balint-Kurti QDR lecture

  7. Quantitative trait loci are genetic loci which are associated with a change in the trait under investigation. • One or more linked genes may underlie a QTL P Balint-Kurti QDR lecture

  8. Finding dQTL P Balint-Kurti QDR lecture

  9. Why are we interested in Quantitative Resistance? • After all, major-gene resistance gives higher resistance and is easier to manipulate. • Durability • Resistance to necrotrophic pathogens • Quantitative disease resistance to biotrophic pathogens exists also • But there is no (?) major-gene resistance to necrotrophs. P Balint-Kurti QDR lecture

  10. What do we know about Quantitative Resistance? • We have mapped a lot of QTL • Beyond that not much- • No publications on cloned genes • Yet it is arguably the most important form of resistance used in breeding • Why is there this lack of knowledge? P Balint-Kurti QDR lecture

  11. Disease Resistance QTL are everywhere! • >89% of maize genome covered P Balint-Kurti QDR lecture

  12. Why? • Lots of Diseases • Lots of Genes • Lots of imprecision • Some genes are map inaccurately • Most genes are mapped imprecisely P Balint-Kurti QDR lecture

  13. Is the dogma true- do these dichotomies really exist? P Balint-Kurti QDR lecture

  14. Do these dichotomies really exist? P Balint-Kurti QDR lecture

  15. Is this dogma true- do these dichotomies really exist? P Balint-Kurti QDR lecture

  16. Is quantitative resistance really non-race –specific? • Several publications suggest that some QTL are race specific • Marcel et al looked at Barley leaf rust system. • Suggested that some of the smaller effect QTL are race-specific • Suggested the existence of a minor gene –for-minor gene interaction P Balint-Kurti QDR lecture

  17. In this case detection of race-specific QTL depended on how the analysis was done P Balint-Kurti QDR lecture

  18. P Balint-Kurti QDR lecture

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