Investigating Root System Architectural Traits in Durum Wheat to Improve Adaptation to Drought and Crown Rot Conditions - ISRR 2018 10th Symposium for the International Society of Root Research

Samir Alahmad ¹ Kai Voss-Fels ¹ Jason Able ² Filippo Bassi ³ Jack Christopher ⁴ Lee Hickey ¹

¹Queensland Alliance for Agriculture and Food Innovation, The University of Queensland QLD, 4072, Australia
²School of Agriculture, Food and Wine, Waite Research Institute, The University of Adelaide, Urrbrae, SA, 5064, Australia
³Durum Breeding Program, International Center for the Agricultural Research in the Dry Areas, Rabat, 10000, Morocco
⁴Queensland Alliance for Agriculture and Food Innovation, The University of Queensland, Leslie Research Facility, QLD, 4350,, Australia

Durum wheat (Triticum turgidum L. ssp. durum) producers can experience significant yield and grain losses due to crown rot (CR) disease, caused primarily by a fungal pathogen Fusarium pseudograminearum. Losses due to CR are exacerbated when disease infection coincides with terminal drought. Durum wheat is very susceptible to CR and resistant germplasm is not currently available in elite breeding pools. Deploying physiological traits for drought adaption (e.g. deeper roots), to reduce stress due to water deficit may, therefore, potentially reduce losses due to CR infection.

The rapid generation advance technology, ‘speed breeding’, was used to rapidly develop recombinant inbred lines (RIL) populations (F6) derived from crosses between Australian cultivars and ICARDA elite breeding lines pre-selected for drought adaptation in Syria and Morocco. Populations were evaluated in the field and under controlled conditions for several physiological traits, including seminal root angle and number and CR severity. This provided information on the genetic predisposition of lines for rooting behaviour and CR susceptibility in the absence of water stress. Field experiments were established in Queensland, Australia, which allowed an examination of the value of root development traits to improve adaptation to each of the stresses. NDVI measurements were recorded weekly, which enabled modelling of the senescence pattern and calculation of stay-green traits for each genotype. Genome-wide association studies using DArT markers identified key genomic regions underpinning the traits. Our genetic analyses highlighted the genetic relationships between yield as well as above- and below-ground physiological traits.

Through this study, we have provided new insights into the genetic controls and value of these traits, which we anticipate will assist breeders to design improved durum varieties that may help to mitigate production losses due to water deficit and CR.