Genetic variation in the gravitropic response of maize roots to low temperatures

Abstract

Abstract:The distribution of roots in soil determines their acquisition of spatially varying resources. It may be altered by changing the response of roots to gravity. The aim of the study was to assess gravitropic set-point angles (GSAs) of maize (Zea mays L.) roots, their response to temperature and the feasibility to measure them in growth pouches. The GSAs of the primary, seminal and crown roots of a set of nine temperate inbred lines were measured. The lines were grown under controlled conditions in growth columns either at 15/13°C or 24/20°C (day/night) until the two-leaf stage (V2). The GSA was measured as the deviation of the initial 3 cm of root axis from the vertical zero. Low temperature resulted in a decrease in the GSAs of the crown roots by 10°, i.e. the roots oriented more vertically. The effect of the GSAs on the distribution of the roots was verified in wider columns using two extreme inbred lines. The proportion of roots in the upper 5 cm of the columns was 78% for the line S335 with the strongest tendency to horizontal root growth and only 39% for CM105 with almost vertical orientation of the roots. The differences in GSAs between these two genotypes were even more pronounced in growth pouches, thus proving the feasibility of this system for rapid screening. The results indicate that there is a huge genetic variability available to alter the growth direction of the seedling roots of maize. However, there was little effect of the temperature.

Shovelomics root traits assessed on the EURoot maize panel are highly heritable across environments but show low genotype-by-nitrogen interaction

“…Otherwise, the increased mW under high N conditions and on sites with a higher productivity could be a response to the higher N availability in the soil top layer resulting in a stronger expansion of the root system in a horizontal orientation. Conversely, The steeper angle under low N may support a stronger vertical root growth to deeper soil layers (Hund 2010;Trachsel et al 2013;Uga et al 2013) and can be advantageous under drought (Uga et al 2013). Yet, based on the correlation with shoot traits it is difficult to judge where a selection to one or the other extreme would lead.…”

Steep, cheap and deep: an ideotype to optimize water and N acquisition by maize root systems

“…The growth angle of axial roots is a primary determinant of root foraging depth. It is well established that the growth angle of axial roots is related to rooting depth in several crop species (Oyanagi et al, 1993;Bonser et al, 1996;Liao et al, 2001;Kato et al, 2006;Manschadi et al, 2008;Hund, 2010;Singh et al, 2011), which in turn is closely correlated with the depth of soil resource acquisition, with shallow growth angles being superior for topsoil foraging and therefore P acquisition (Lynch and Brown, 2001;Zhu et al, 2005c) and steep growth angles being superior for water acquisition under drought (Ho et al, 2005;Mace et al, 2012). In maize, genotypic variation for the growth angle of crown roots is well correlated with the depth of root placement (Fig.…”

Shovelomics: high throughput phenotyping of maize (Zea mays L.) root architecture in the field

“…Genotypes were not replicated. Additionally the IBM RILs were grown in Alma in /2010 were grown in Rock Springs with four replicates. Genotypes were randomly assigned to plots in each location and in both years using a randomized complete block design.…”

“…Moreover artificial systems fail to mimic the complex interaction between the plant, intrinsic abiotic and biotic soil parameters and prevailing environmental conditions as suggested by Walter et al (2009). In the field, roots and shoots are exposed to very different environmental conditions, especially with regard to temperature, which is an important regulator of root development (Hund 2010). In controlled conditions, field environments to which the shoot is exposed are typically simulated, leading to highly artificial conditions for the root system.…”