2007 Volume 1 Pages 57-65
We evaluated variation in nodal root angle in the genus Zea and performed quantitative trait locus (QTL) mapping for the trait. Angle (in degrees) of roots emerging from the second (2nd-root angle) and third (3rd-root angle) nodes from the bottom of shoot showed wide variation in nine accessions; relatively high repeatability was obtained. QTL analyses controlling root angle were performed in the two sets of F2 populations (127 individuals in Trial A and 123 in Trial B) developed from different crossings of maize B73 (deep-rooting) × teosinte Zea luxurians (shallow-rooting). In Trial A, we used an SSR-based map with 107 markers, covering 1,329 cM throughout all ten chromosomes. By composite interval mapping analysis, four QTLs were identified, two on chromosome 10 for 2nd-root angle and one each on chromosomes 2 and 7 for 3rd-root angle. In Trial B, using a 1,397 cM SSR-based map with 92 markers, one QTL was located on chromosome 4 and two on chromosome 7 for 2nd-root angle and one each on chromosomes 2, 4 and 7 for 3rd-root angle. The QTL on chromosome 7 (identified as Qra2nd3rd7.04) was consistently found across the trials. A potential role of the Qra2nd3rd7.04 in controlling angles of nodal roots and thus flooding tolerance was discussed.