Theoretical and Applied Genetics

, Volume 103, Issue 1, pp 75–83 | Cite as

Evaluation of near-isogenic lines of rice introgressed with QTLs for root depth through marker-aided selection

  • L. Shen
  • B. Courtois
  • K. L. McNally
  • S. Robin
  • Z. Li
Original Paper

Abstract 

Drought is one of the main abiotic constraints in rice. A deep root system contributes efficiently to maintaining the water status of the crop through a stress period. After identifying QTLs affecting root parameters in a doubled-haploid (DH) population of rice derived from the cross IR64/Azucena, we started a marker-assisted backcross program to transfer the Azucena allele at four QTLs for deeper roots (on chromosomes 1, 2, 7 and 9) from selected DH lines into IR64. We selected the backcross progenies strictly on the basis of their genotypes at the marker loci in the target regions up to the BC3F2. We assessed the proportion of alleles remaining from Azucena in the non-target areas of the BC3F2 plants, which was in the range expected for the backcross stage reached. Twenty nine selected BC3F3 near-isogenic lines (NILs) were developed and compared to IR64 for the target root traits and three non-target traits in replicated experiments. Of the three tested NILs carrying target 1, one had significantly improved root traits over IR64. Three of the seven NILs carrying target 7 alone, as well as three of the eigth NILs carrying both targets 1 and 7, showed significantly improved root mass at depth. Four of the six NILs carrying target 9 had significantly improved maximum root length. Five NILs carrying target 2 were phenotyped, but none had a root phenotype significantly different from that of IR64. A re-analysis of the initial data with the composite interval mapping technique revealed two linked QTLs with opposite effects in this area. Some NILs were taller than IR64 and all had a decreased tiller number because of a likely co-introgression of linked QTLs. The usefulness of NILs, the efficiency of marker-aided selection for QTLs and the relationship between root traits are discussed. The NILs with an improved root system will permit testing the importance of root depth for water-limited environments.

Keywords Drought tolerance Oryza sativa Root depth Near-isogenic lines Marker-aided selection Introgression QTLs 

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

Copyright information

© Springer-Verlag Berlin Heidelberg 2001

Authors and Affiliations

  • L. Shen
    • 1
  • B. Courtois
    • 1
  • K. L. McNally
    • 1
  • S. Robin
    • 1
  • Z. Li
    • 1
  1. 1.International Rice Research Institute, MCPO Box 3127, 1271 Makati City, The Philippines Fax: 33 4 67 61 56 05; e-mail: brigitte.courtois@cirad.fr, Present address: L. Shen, Plant Molecular Genetics Laboratory, Texas Tech University, TX79409-2122, USA, Present address: B. Courtois, CIRAD-AMIS, TA40/03, Avenue Agropolis, 34398 Montpellier Cedex 5, France, Present address: S. Robin, Deptartment of Crop Improvement, Agricultural College and Research Institute, Navalur Kuttapattu, Trichy 9, Tamil Nadu, IndiaPH

Personalised recommendations