Association analysis of genes involved in maize (Zea mays L.) root development with seedling and agronomic traits under contrasting nitrogen levels

Abstract

A better understanding of the genetic control of root development might allow one to develop lines with root systems with the potential to adapt to soils with limited nutrient availability. For this purpose, an association study (AS) panel consisting of 74 diverse set of inbred maize lines were screened for seedling root traits and adult plant root traits under two contrasting nitrogen (N) levels (low and high N). Allele re-sequencing of RTCL, RTH3, RUM1, and RUL1 genes related to root development was carried out for AS panel lines. Association analysis was carried out between individual polymorphisms, and both seedling and adult plant traits, while controlling for spurious associations due to population structure and kinship relations. Based on the SNPs identified in RTCL, RTH3, RUM1, and RUL1, lines within the AS panel were grouped into 16, 9, 22, and 7 haplotypes, respectively. Association analysis revealed several polymorphisms within root genes putatively associated with the variability in seedling root and adult plant traits development under contrasting N levels. The highest number of significantly associated SNPs with seedling root traits were found in RTCL (19 SNPs) followed by RUM1 (4 SNPs) and in case of RTH3 and RUL1, two and three SNPs, respectively, were significantly associated with root traits. RTCL and RTH3 were also found to be associated with grain yield. Thus considerable allelic diversity is present within the candidate genes studied and can be utilized to develop functional markers that allow identification of maize lines with improved root architecture and yield under N stress conditions.

Activation of seminal root primordia during wheat domestication reveals underlying mechanisms of plant resilience

“…In such environments, a shift in resource allocation from above to below ground organs is expected (Poorter & Remkes, ), and selection pressures towards a higher number of seminal roots and lower shoot:root ratio may occur. In maize, SRN and length were positively correlated with shoot weight under low phosphorous levels (Zhu et al, ) and with grain yield under both low and high nitrogen levels (Abdel‐Ghani et al, ). It has been suggested that SRN has been selected inadvertently as an adaptive trait during domestication (Salvi, ; Tai et al, ).…”

“…root ratio may occur. In maize, SRN and length were positively correlated with shoot weight under low phosphorous levels (Zhu et al, 2006) and with grain yield under both low and high nitrogen levels (Abdel-Ghani et al, 2015). It has been suggested that SRN has been selected inadvertently as an adaptive trait during domestication (Salvi, 2017;Tai et al, 2017).…”

Making better maize plants for sustainable grain production in a changing climate

“…Additionally, cortical aerenchyma in roots can enhance maize growth and development in soil with N/P/K deficiencies ( Postma and Lynch, 2010 , 2011 ). Studies on maize root adaptation to N/P/K deficiency have recently been extended using proteomic, transcriptomic, and metabolomic approaches ( Li et al, 2007 ; Simons et al, 2014 ; Abdel-Ghani et al, 2015 ; Trevisan et al, 2015 ). These approaches could provide substantial genetic resources for the improvement of maize root architecture.…”

Non-syntenic genes drive RTCS-dependent regulation of the embryo transcriptome during formation of seminal root primordia in maize (Zea maysL.)

“…Moreover, at later developmental stages, seminal root length and number are positively correlated with shoot biomass at low phosphorus levels (Zhu et al , 2006). Furthermore, seminal root length correlates with grain yield under both low and high nitrogen levels (Abdel-Ghani et al , 2015). Other seminal root traits such as number, angle, and diameter have been considered in designing hypothetical root ideotypes optimized for maize adaptation to a range of environmental stresses and increased sustainability of water and nutrient acquisition (Lynch, 2013).…”