Quantitative trait loci (QTL) controlling plant architecture traits in a Solanum lycopersicum x S-pimpinellifolium cross

Plant architecture is an important determinant of tomato yield because it affects light distribution within a crop canopy. One hundred and eleven lines of a BC1F8 population developed from Solanum lycopersicum 'M570018' and its wild relative Solanum pimpinellifolium (PI124039) were grown in a glasshouse in spring and autumn, and plant architecture traits evaluated at two leaf positions: the last leaf before floral initiation (F leaf) and the largest leaf (L leaf). QTL analysis was performed using QTLNetwork 2.1; 23 additive QTLs and seven epistatic QTLs were detected for 13 of 16 traits measured in this study. On chromosomes 2 and 12, QTLs for the leaf drooping angle (DRAN) of the F leaf (fdran2 and fdran12) co-located with QTLs for canopy size (CAN) at each leaf position of the F and L leaves (fcan2 and lcan2, fcan12 and lcan12). On chromosome 3, QTLs for leaf length (LL) of the F and L leaves (fll3 and lll3) co-located with the epistatic QTL for CAN at the L leaf (lcan3). QTLs for plant height (PH) were detected on chromosome 2, 3, 4, and 6; all of these QTLs (ph2, ph3, ph4, and ph6) decreased PH in the presence of Solanum lycopersicum (SL) alleles. QTLs for total leaf number and internode length were detected on chromosomes 3 and 4; tln3 and int4 mapped in the vicinity of ph3 and ph4, respectively. The co-localization of QTLs associated with CAN, DRAN, and LL suggests canopy size is determined by both leaf length and leaf drooping angle in tomato.