Key for pachytene chromosome identification • 1st criteria: Chromosome with NOR vs without with: chromosome 2 • 2nd criteria: Position of the centromere • a) Median chromosomes 5, 11, 12 (metacentric) • b) Sub median all others (sub-metacentric) • 3rd criteria: Short arm heterochromatic regions • a) A conspicuous cluster of chromomeres compressed together: chromosomes. 3, 4, 6. • b) More than 1 cluster of chromomeres: chromosomes. 1, 7, 10.
Tomato Mapping Stocks LA 1182 sy - sf(3) alb - mua (12) LA1441 coa - c(6) a - hl (11) LA1443 scf - dgt(1) l -al(8) LA1444 wd - d(2) af - tf(5) LA1445 clau-di(4) icn - ag(10) LA1446 var - not(7) ah - marm(9)
Distribution of tomato species Zuriaga et al 2008
(based on 6 DNA seq, Adh 2, fw2.2) S. lycopersicon Eulycopersicon (color-fruited) typ: S. cheesmaniae min: S. galapagence S. pimpinellifolium S. neorickii S. chemieleskii Eriopersicon Green-fruited S. peruvianum S. arcanum S. Corneliomuellerii S. huayalasense S. habrochaites S. pennellii S. chilense S. lycopersicoides, S. ochrantum, S. sitiens
Esc-pennelli introgression lines Each stock is homozygous for a single chromosome segment (delineated by RFLP markers) introgressed from L. pennellii, such that the entire wild species genome is represented in a group of 50 lines.
Dissection of QTL se2.1(stigma exertion • Four loci influencing stamen length (three closely linked) were identified. • A single locus for style length was identified (the long style allele was shown to be dominant using esc-penn sustitution lines). • A single locus for anther dehiscence was also found in the region. Chen and Tanksley 2004
Five closely linked genes all contribute to stigma exsertion phenotype. This may be the remnant of a “co adapted gene complex” where linked genes cooperatively contribute to an adaptation, and are inherited as a single unit.