Posts Tagged ‘qtl’

Drought stress and tropical maize: QTL-by-environment interactions and stability of QTLs across environments for yield components and secondary traits

Posted by on , in Journal Articles

Published in Theoretical and Applied Genetics 119(5): 913-930, 2009

Drought stress and tropical maize: QTL-by-environment interactions and stability of QTLs across environments for yield components and secondary traits

Rainer Messmer, Yvan Fracheboud, Marianne Bänziger, Mateo Vargas, Peter Stamp and Jean-Marcel Ribaut

A recombinant inbred line (RIL) population was evaluated in seven field experiments representing four environments: water stress at flowering (WS) and well-watered (WW) conditions in Mexico and Zimbabwe. The QTLs were identified for each trait in each individual experiment (single-experiment analysis) as well as per environment, per water regime across locations and across all experiments (joint analyses). For the six target traits (male flowering, anthesis-to-silking interval, grain yield, kernel number, 100-kernel fresh weight and plant height) 81, 57, 51 and 34 QTLs were identified in the four step-wise analyses, respectively. Despite high values of heritability, the phenotypic variance explained by QTLs was reduced, indicating epistatic interactions. About 80, 60 and 6% of the QTLs did not present significant QTL-by-environment interactions (QTL × E) in the joint analyses per environment, per water regime and across all experiments. The expression of QTLs was quite stable across years at a given location and across locations under the same water regime. However, the stability of QTLs decreased drastically when data were combined across water regimes, reflecting a different genetic basis of the target traits in the drought and well-watered trials. Several clusters of QTLs for different traits were identified by the joint analyses of the WW (chromosomes 1 and 8) and WS (chromosomes 1, 3 and 5) treatments and across water regimes (chromosome 1). Those regions are clear targets for future marker-assisted breeding, and our results confirm that the best approach to breeding for drought tolerance includes selection under water stress.

New book in the library: Wheat Science and Trade

Posted by Petr Kosina on , in New Acquisitions

wheatWheat: Science and Trade is an up-to-date, comprehensive reference work designed to expand the current body of knowledge on this staple crop, incorporating new information made available by genetic advances, improvements in the understanding of wheat’s biology, and changes in the wheat trade industry. Covering phylogeny and ontogeny, manipulation of the environment and optimal management, genetic improvement, and utilization and commercialization, the book focuses on the most economically significant diseases and impacts.

Wheat: Science and Trade is divided into four major sections covering all aspects of the wheat plant, crop, cultivar and industry.  Section one offers a firm grounding in the development and domestication of wheat with an extensive overview of diseases and pathogens following in Section two. Section three focuses on genetic strategies including QTL detection and marker-assisted selection, genome organization and comparative genomics, and synthetic wheat as an emerging technology.  Section four concludes the text with a discussion of changes in industry trade, quality assessment, and new uses for wheat and modified wheat products.

Written by a global team of expert authors, Wheat: Science and Trade is presented in a user-friendly format making it equally accessible to a wide variety of readers.  Applicable for the academic, research, consulting, and end-user communities, this text is a must have reference on this key staple crop.

Key Features:

  • Provides an up-to-date authoritative reference on a globally consumed and produced crop
  • Focuses on the most economically significant production constraints and impacts
  • Includes interconnecting sections on the wheat plant, crop, cultivar, and industry
  • Includes chapters from a world-wide team of leading experts
  • Provides concise summaries for each chapter and perspectives on emerging research areas

The book includes two chapters co-authored by CIMMYT scientists Julie Nicol and Ivan Ortiz Monasterio.