title: Traits and QTLs for development of dry direct-seeded rainfed rice varieties.
abstract: The development of rice varieties for dry direct-seeded conditions can be accelerated by selecting suitable traits. In the present investigation, traits hypothesized to be important for direct-seeded conditions in rainfed systems, including seedling emergence, early vegetative vigour, nutrient uptake, nodal root number, and root hair length and density, were characterized to study the genetic control of these traits and their relationship with grain yield under seedling- and reproductive-stage drought stress. Two BC₂F₄ mapping populations derived from crosses of Aus276, a drought-tolerant aus variety, with MTU1010 and IR64, high-yielding indica mega-varieties, were developed and studied to identify quantitative trait loci (QTLs) that showed large and consistent effects. A total of 26 QTLs associated with 23 traits and 20 QTLs associated with 13 traits were mapped in the Aus276/3*IR64 and Aus276/3*MTU1010 populations, respectively. qGY₆.₁, qGY₁₀.₁, qGY₁.₁, and qEVV₉.₁ were found to be effective in both populations under a wide range of conditions. QTLs for several seedling-stage traits co-located with QTLs for grain yield, including early vegetative vigour and root hair length. On chromosome 5, several QTLs for nutrient uptake co-located with QTLs for root hair density and nematode gall rating. Six lines were selected from both populations based on grain yield and the presence of QTLs, and these lines typically showed improved seedling-stage traits (nodal root number, dry shoot weight, and root hair length and density). The co-located QTLs identified here can be used in research aimed at increasing the yield and adaptability of rainfed rice to direct-seeded conditions.
authors.affiliation: Division of Plant Breeding, Genetics, and Biotechnology, International Rice Research Institute, DAPO Box 7777, Metro Manila, The Philippines Department of Molecular Biology and Biotechnology, CCS Haryana Agricultural University, Hisar-125004, India.
authors.forename: Nitika
authors.initials: N
authors.lastname: Sandhu
authors.affiliation: Crop and Environmental Sciences Division, International Rice Research Institute, DAPO Box 7777, Metro Manila, The Philippines.
authors.forename: Rolando O
authors.initials: RO
authors.lastname: Torres
authors.affiliation: Division of Plant Breeding, Genetics, and Biotechnology, International Rice Research Institute, DAPO Box 7777, Metro Manila, The Philippines.
authors.forename: Ma Teresa
authors.initials: MT
authors.lastname: Sta Cruz
authors.affiliation: Division of Plant Breeding, Genetics, and Biotechnology, International Rice Research Institute, DAPO Box 7777, Metro Manila, The Philippines.
authors.forename: Paul Cornelio
authors.initials: PC
authors.lastname: Maturan
authors.affiliation: Department of Molecular Biology and Biotechnology, CCS Haryana Agricultural University, Hisar-125004, India.
authors.forename: Rajinder
authors.initials: R
authors.lastname: Jain
authors.affiliation: Division of Plant Breeding, Genetics, and Biotechnology, International Rice Research Institute, DAPO Box 7777, Metro Manila, The Philippines.
authors.forename: Arvind
authors.initials: A
authors.lastname: Kumar
authors.affiliation: Crop and Environmental Sciences Division, International Rice Research Institute, DAPO Box 7777, Metro Manila, The Philippines a.henry@irri.org.
authors.forename: Amelia
authors.initials: A
authors.lastname: Henry
mesh_terms: D002874:Chromosome Mapping; D055864:Droughts; D002523:Edible Grain / Q000235:genetics / Q000254:growth & development*; D012275:Oryza / Q000235:genetics* / Q000254:growth & development*; D010641:Phenotype; D011110:Polymorphism, Genetic; D040641:Quantitative Trait Loci; D036226:Seedlings
keywords: Direct-seeded rice; early vegetative vigour; grain yield; nutrient uptake; quantitative trait loci (QTLs); root.