Identification of chromosomal segments and gibberellins affecting potato (Solanum tuberosum L.) development

Linkage maps from restriction fragment length polymorphisms (RFLP's) segregating in two reciprocal back-crosses of Solanum tuberosum (tbr) and S. berthaultii (ber) were used to detect quantitative trait loci (QTL) associated with earliness of tuberization, branching, leaf size, and tuber dormancy. To study gibberellin (GA) metabolism, radioactive GA{dollar}sb{lcub}12{rcub}{dollar}-aldehyde and GA{dollar}sb{lcub}12{rcub}{dollar} were fed to shoot apices of S. tuberosum ssp. andigena normal and dwarf plants grown under long and short photoperiods.; Using RFLP-linkage analysis ten QTL on eight chromosomes were detected for earliness of tuberization. Earliness was favored by a tbr allele in seven cases, and by an allele from the late S. berthaultii in three cases. Five of the seven tbr alleles favoring earliness were detected through RFLP's segregating from the S. tuberosum parent to which the hybrid was back-crossed. QTL on nine chromosomes affected tuber dormancy. These were found through RFLP-linkage analysis and tests for epistatic interactions. At most QTL for dormancy, ber prolonged dormancy. Long dormancy was recessive at most QTL. Several RFLP markers associated with earliness traits were also associated with tuber dormancy, leaf size, and branching, showing genetic relationships between these traits that could not be detected by conventional correlation analysis. Epistasis complicated the interpretation of results from the genetic mapping studies.; Most of the principal members of the early-13-hydroxylation pathway (GA{dollar}sb{lcub}53{rcub}{dollar}-aldehyde, GA{dollar}sb{lcub}53{rcub}{dollar}, GA{dollar}sb{lcub}44{rcub}{dollar}, GA{dollar}sb{lcub}19{rcub}{dollar}, GA{dollar}sb{lcub}20{rcub}{dollar}, GA{dollar}sb1{dollar}, GA{dollar}sb{lcub}29{rcub}{dollar}, and GA{dollar}sb8{dollar}) were detected by gas chromatography-mass spectrometry after high performance liquid chromatography purification. The detection of GA{dollar}sb{lcub}51{rcub}{dollar} implied that the non-hydroxylation pathway was also active. The dwarfs, which had a much longer critical photoperiod for tuberization than the wild types, appeared to have a partial metabolic block between GA{dollar}sb{lcub}12{rcub}{dollar} and GA{dollar}sb{lcub}53{rcub}{dollar}. Thus a block in the early-13-OH pathway was associated with ability to tuberize under long photoperiods. No differences in {dollar}lbracksp{lcub}14{rcub}{dollar}C) GA metabolism were detected between plants grown under 10-h and 16-h photoperiods, suggesting that the photoperiodic control on levels of bioactive GA is prior to GA{dollar}sb{lcub}12{rcub}{dollar}-aldehyde.