Plant Genomics

Biography

Biography: Jianlong Xu

Abstract

Low and unstable productivity from multiple   abiotic stresses   are characteristic in the rice production of most rainfed are as of Asia and Africa. In 2007, we initiated backcross (BC)  breeding  procedure for improving yield and tolerances to multiple  ab iotic  stresses. Using 8 BC1 populations derived from a widely adaptable and high yielding recipient and 8 donors plus two round s of phenotypic sele ction, we were able to develop 496 introgression lines (ILs) with significantly improved yields under drough t, salt and/or non-stress conditions. From these ILs, 6 new varieties were released for the rainfed and irrigated areas of Philippines and Pakistan and many more are in the pipeline to be released in several countries.  Genetic  characterization by SSR markers reveal three interesting aspects of donor introgression in the selected BC1F2 plants and BC1F3 lines: (1) introgression frequency in BC   progenies   was characteristic to specific crosses; (2) donor introgression at different   ge nomic regions   of the selected ILs varied considerabl y across the  genome  resulting at  lea st partially from strong selection for target traits; (3) there was greatly reduced  heterozygosity  in the selected BC progenies, particularly with selection under drought and salinit  y. The strong phenotypic selection for abiotic stress tolerances at early segregating generation appeared to offer major advantages over the conventional pedigree  breeding  approach by not only allowing one or more  a biotic  stress tolerances integrated into elite backgrounds, but being able to achieve quicker  homozygosity  in the selected  progenies . The trait specific ILs are good materials for discovery of  genes /QTL underlying the target and non-target traits and for highly ef ficient development of Green Super Rice by designed QTL pyram iding .