Proceedings of the XLVI Italian Society of Agricultural Genetics - SIGA Annual Congress

Giardini Naxos, Italy - 18/21 September, 2002

ISBN 88-900622-3-1

Poster Abstract - 4.15

QTLs for vertical root pulling resistance in maize and overlap with QTLs for Hydroponic root traits and grain yield at different water regimes

LANDI P.*, DARRAH L.L.**, GIULIANI M.M.*, NOLI E.*, STEFANELLI S.*, CONTI S.*

*) Dept. of Agro-environmental Sciences and Technology, University of Bologna

**) Plant Genetics Res. Unit, Agric. Res. Service, U. S. Dept. of Agric. and Dept. of Agronomy, University of Missouri, Columbia, U.S.A.

drought tolerance, QTLs, root strength, seminal roots, maize

Vertical root pulling resistance (VRPR) is a trait used to estimate root strength in maize (Zea mays L.). Its measurement is laborious and destructive; hence, the possibilities of studying root strength without resorting to VRPR and/or of conducting marker assisted selection (MAS) for VRPR would be of great benefit for breeding. Objectives of this investigation were: (I) identify the chromosomal segments (QTLs) controlling VRPR; (II) study the overlap between QTLs for VRPR and QTLs for both root traits in hydroponic culture and for grain yield under well-watered (GY-WW) and water-stressed (GY-WS) conditions; (III) develop strategies of MAS at the detected QTLs. The 118 F₃ families derived from Lo964 X Lo1016 were tested for VRPR (three locations, one year), for root traits in hydroponics (one trial), for GY-WS, GY-WW (one location, two years) and for a drought tolerance index (DTI) calculated as the ratio between GY-WS and GY-WW. For VRPR, 19 QTLs were detected in at least one location or on the mean across locations. Additive effects were positive for some QTLs and negative for others, consistently with the observed transgressive segregation. Eleven of the detected QTLs overlapped (i.e., their peaks were within a 10 cM interval) with at least one QTL for root traits in hydroponics. Two QTLs on chromosome 1, peaking near csu145 and between PGAMCGT400 and PGAMCTA205 , overlapped with QTLs for three hydroponic root traits. Eleven of the 19 QTLs for VRPR overlapped at least once with QTLs for GY-WW, GY-WS and/or DTI. Three of such common QTLs showed consistency of sign of additive effects for VRPR and for GY-WW, GY-WS and DTI; two of them were the QTLs on chromosome 1 that also overlapped with root traits in hydroponics. Results suggested that MAS can be conducted at these two QTLs to improve both root strength and yield performance across WW and WS conditions.