Genetic screening for mutants with altered seminal root numbers in hexaploid wheat using a high-throughput root phenotyping platform

Abstract

The root is the main channel for water and nutrient uptake in crops. Optimisation of root architecture provides a viable strategy to improve nutrient and water uptake efficiency and maintain crop productivity under water-limiting, nutrient-poor conditions. We know little, however, about the genetic control of root development in wheat, a crop supplying 20% of global calorie and protein intake. To improve our understanding of the genetic control of root development in wheat, we conducted a high-throughput screen for variation in seminal root number using an exome-sequenced hexaploid wheat mutant population. The screen identified eight independent mutants with homozygous and stably inherited altered seminal root number phenotypes, referred to as arn1 to arn8. One mutant, arn1, displays a recessive extra seminal root number phenotype, while six mutants (arn2, arn4 to arn8)show dominant lower seminal root number phenotypes. Segregation analysis in F 2 populations suggest that the arn1 phenotype is controlled by multiple genes while the arn2 phenotype fits a 3:1 segregation ratio characteristic of single gene action. This work highlights the potential to use the sequenced wheat mutant population as a forward genetic resource to uncover novel variation in agronomic traits, such as seminal root architecture. Characterisation of the mutants and identification of the genes defining this variation should aid our understanding of root development in wheat.

Root system architecture in cereals: progress, challenges and perspective

“…This ‘hidden half’ of plants is a conduit for resource uptake from the soil, and logically a high‐value target for manipulation to improve crop productivity on nutrient‐deficient soils (Meister et al., 2014). Besides anchorage, storage functions, synthesis and accumulation of secondary metabolites, root systems serve as an interface for symbiotic microbial relationships (Khan et al., 2016; Shorinola et al., 2019). Roots are becoming a key target for a second green revolution, and are deemed essential for production of high‐yielding food grains such as wheat and rice (Gewin, 2010).…”

Deciphering the genetic basis of wheat seminal root anatomy uncovers ancestral axial conductance alleles

“…As the root develops, some of the peripheral elements can increase in size becoming similar to the initial CMX. In recent years, several studies on root system architecture uncovered the genetic basis of these traits, however, most studies focused on the geometric traits, such as root number, length, diameter and, angle (Christopher et al, 2013; Golan et al, 2018; Hamada et al, 2012; Shorinola et al, 2019; Soriano & Alvaro, 2019; Voss‐Fels, Snowdon, & Hickey, 2018). On the other hand, root anatomical traits were less studied and remain largely unexplored.…”

Shaping polyploid wheat for success: Origins, domestication, and the genetic improvement of agronomic traits

“…The importance of the "hidden half" in polyploid wheats The "hidden half" of wheat, referring to the root system, plays fundamental roles in ensuring nutrient and water uptake efficiency, and thus the adaptability of wheat to diverse growth environments. High-throughput screening of mutant populations, genetic mapping studies, and gene transcriptome profiling have found multiple mutants with altered root architecture, QTLs for wheat root traits, and candidate genes and signaling pathways relating to root development (An et al, 2006;He et al, 2014;Shorinola et al, 2019;Zhuang et al, 2021). These QTLs/genes tend to be related to plant hormone (BR, AUX, and cytokinin) signaling and ROS homeostasis (He et al, 2014;Zhuang et al, 2021).…”