Identification of QTLs for new formed root architectural traits in rice (Oryza sativa L.) after transplantation

Transplanting has been the most widespread planting technique for rice production in Asia. It is estimated that more than 85% of rice production in china, and almost 100% in Northeast China adopted transplanting. The healthy and vigorous seeding can reduce thetransplanting shock’ and is the most important for final yield formation. The large root diameter, long root length, large surface area and more root number of new formed root are the major parameters for healthy and vigorous seeding. Nipponbare, Kasalath and ninety-eight backcross recombinant inbred lines (BC1F5) derived from a cross between them were used to detect QTL controlling new formed root traits after transplanting. The healthy seeding was transplanted at fourth leaf stage. And the average root diameter, total root length, average surface area, root length and root number of new formed root were measured at 7 days after transplanting. The qARD3 associated with average root diameter was detected on chromosome 3.Two putative QTLs controlling total root length were detected on chromosomes 5 (qRL5) and 8 (qRL8). One QTL qASA5 affecting average surface area was detected on chromosomes 5. The qARL5 affecting average root length was identified at the same region with qRL5 and qASA5.Three QTLs associated with root number were detected on chromosomes 1 (qRN1), 3 (qRN3) and 5 (qRN5). The phenotypic variations (VE) explained by individual QTL were ranged from 8.6% to 24.2%. A QTLs cluster formed on chromosome 5. The qRN3 and qRL8 were new locus for new formed root traits after transplanting. The QTLs cluster on chromosome 5 was also a new region. These QTLs provided “elements” and basic-information for transplanting root architecture and elucidation of root architecture molecular mechanism after transplanting of rice.