The genetic architecture of nodal root number in maize

Abstract

The maize nodal root system plays a crucial role in the development of the aboveground plant and determines the yield via the uptake of water and nutrients in the field. However, the genetic architecture of the maize nodal root system is not well understood, and it has become the 'dark matter' of maize genetics. Here, a large teosinte-maize population was analyzed, and high-resolution mapping revealed that 62 out of 133 quantitative trait loci (QTLs), accounting for approximately half of the total genetic variation in nodal root number, were derived from QTLs for flowering time, which was further validated through a transgenic analysis and a genome-wide association study. However, only 16% of the total genetic variation in nodal root number was derived from QTLs for plant height. These results gave a hint that flowering time played a key role in shaping nodal root number via indirect selection during maize domestication. Our results also supported that more aerial nodal roots and fewer crown roots might be favored in temperate maize, and this root architecture might efficiently improve root-lodging resistance and the ability to take up deep water and nitrogen under dense planting.

Biochar addition coupled with nitrogen fertilization impacts on soil quality, crop productivity, and nitrogen uptake under double‐cropping system

“…Plant roots are the vital source for the supply of nutrients to plant shoots. Thus, shoots and roots are directly proportional to each other (Zhang et al, 2018). Our results verified that TRL, TRSA, and Pn were significantly correlated with grain yield (0.70*, 0.74*, and 84*) under biochar amendments (Table 7).…”

Maize brace roots provide stalk anchorage

“…While the gene or genes underlying this major qtl have not been determined, the location overlaps with cct1 (constans, constans-like, toc1; B73 v4: Zm00001d024909), a major determinant of photoperiod responses in maize [Hung et al, 2012]. A separate study of a maize-teosinte BC 2 S 3 population showed significant overlap for brace root whorl number qtl and flowering time qtl [Zhang et al, 2018b], suggesting a link between the control of flowering time and brace root whorl numbers. It is unknown if modulating flowering time is sufficient to alter the number of brace root whorls in the soil, and thus affect lodging-resistance.…”

“…Although optimal brace root traits for root lodging-resistance have been identified, there are limited reports to define the genetic basis of these traits. The studies that have been reported primarily focus on the total number of brace root whorls [Zhang et al, 2018a, Ku et al, 2012, Gu et al, 2017, Zhang et al, 2018b, with only one study differentiating between the number of brace root whorls that enter the soil and the total number of brace root whorls [Ku et al, 2012]. In this study, an analysis of recombinant inbred line (ril) and immortalized F2 (if2) populations identified both shared and independent quantitative trait loci (qtl) for brace root whorls in the soil and the total number of brace root whorls [Ku et al, 2012].…”

“…Previous work has described a relationship between the number of nodes producing brace roots and flowering time in maize [Zhang et al, 2018b]. However, the described relationship does not take into account the number of brace root whorls that enter the soil, nor their relative contribution to anchorage.…”

Nucleotide Diversity and Association Analysis of ZmMADS60 with Root Length in the Maize Seedling Stage

“…The root domestication syndrome in the common bean was associated with genes that were directly selected to increase seed weight, but had a significant effect on early root growth through a developmental pleiotropic effect [49]. Zhang et al (2015) [51] also revealed that the underground nodal root number was generally regulated by the aboveground trait of flowering time via indirect selection during maize domestication. Indirect selection has retained large phenotypic variations in teosinte and landrace.…”