Growth of axile and lateral roots of maize: I development of a phenotying platform

Abstract

The objective of this study was to develop a phenotyping platform for the non-destructive, digital measurement of early root growth of axile and lateral roots and to evaluate its suitability for identifying maize (Zea mays L.) genotypes with contrasting root development. The system was designed to capture images of the root system within minutes and to batch process them automatically. For system establishment, roots of the inbred line Ac7729/TZSRW were grown until nine days after germination on the surface of a blotting paper in pouches. An A4 scanner was used for image acquisition followed by digital image analysis. Image processing was optimized to enhance the separation between the roots and the background and to remove image noise. Based on the root length in diameter-class distribution (RLDD), small-diameter lateral roots and large-diameter axile roots were separated. Root systems were scanned daily to model the growth dynamics of these root types. While the axile roots exhibited an almost linear growth, total lateral root length increased exponentially. Given the determined exponential growth, it was demonstrated that two plants, germinated one day apart but with the same growth rates differed in root length by 100%. From the growth rates we were able to identify contrasting genotypes from 236 recombinant inbred lines (RILs) of the CML444 x SC-Malawi cross. Differences in the growth of lateral roots of two selected RILs were due to differences in the final length and linear density of the primary lateral roots, as proven by the manual reanalysis of the digital images. The high throughput makes the phenotyping platform attractive for routine genetic studies and other screening purposes.

Duplicate and Conquer: Multiple Homologs ofPHOSPHORUS-STARVATION TOLERANCE1Enhance Phosphorus Acquisition and Sorghum Performance on Low-Phosphorus Soils

“…Because OsPSTOL1 in rice has been shown to enhance early root growth (Gamuyao et al, 2012), which is an important mechanism leading to enhanced P acquisition efficiency under low-P availability, we assessed root morphology traits in sorghum plants from the SAPst grown hydroponically using low-P nutrient solution in a paper pouch system. We observed that total root length and root surface area were positively correlated with grain yield under low-P conditions, which is in agreement with reports indicating that results of root morphology analysis in paper pouches correlate with those of plants grown in soil (Liao et al, 2001;Hund et al, 2009;Miguel et al, 2013). This makes Figure 6.…”

“…Seeds were surface sterilized with sodium hypochlorite (0.5% [w/v] for 5 min) and germinated in moistened paper rolls. After 4 d, uniform seedlings were transferred to moistened blotting papers placed into paper pouches (24 3 33 3 0.02 cm) as described by Hund et al (2009). Each experimental unit consisted of one pouch (three seedlings per paper pouch), whose bottom 3 cm was immersed in containers filled with 5 L of the nutrient solution described by Magnavaca et al (1987) with a P concentration of 2.5 mM (as phosphate; 10 pouches per container).…”

Management of crop water under drought: a review

“…Středa et al 2012) or ex situ (e.g. Hund et al 2009b). Still, roots are promising targets as (i) they are less exploited compared to aboveground traits, (ii) most root traits are compatible with high yield potential and (iii) there is considerable diversity (Trethowan and Mujeeb-Kazi 2008;Lopes and Reynolds 2010;Nakhforoosh et al 2014).…”

Development of a novel semi-hydroponic phenotyping system for studying root architecture

“…The soil-filled root observation chambers (Manschadi et al 2008) or rhizotrons (Wiese et al 2005), and growth pouches (Bonser et al 1996;Liao et al 2004) are often used in studying roots. More recently, an improved pouch system was developed by Hund et al (2009) for rapid measurement of maize (Zea mays L.) root systems during the first days of lateral root growth. In this system, roots grew on the surface of blotting paper facilitating the twodimensional observation of root growth over time.…”