High-Throughput Root Imaging Analysis Reveals Wide Variation in Root Morphology of Wild Adzuki bean (Vigna angularis) Accessions

Abstract

Root system architecture and morphological diversification in wild accessions are important for crop improvement and productivity in adzuki beans. In this study, via analysis using 2-dimensional (2D) root imaging and WinRHIZO Pro software, we described the root traits of 61 adzuki bean accessions in their early vegetative growth stage. These accessions were chosen for study because they are used in Korea’s crop improvement programs; however, their root traits have not been sufficiently investigated. Analysis of variance revealed a significant difference between the accessions of all measured root traits. Distribution analysis demonstrated that most of the root traits followed normal distribution. The accessions showed up to a 17-fold increase in the values in contrasting accessions for the root traits. For total root length (TRL), the values ranged from 82.43 to 1435 cm, and for surface area (SA), they ranged from 12.30 to 208.39 cm2. The values for average diameter (AD) ranged from 0.23 to 0.56 mm. Significant differences were observed for other traits. Overall, the results showed that the accession IT 305544 had the highest TRL, SA, and number of tips (NT), whereas IT 262477 and IT 262492 showed the lowest values for TRL, SA, and AD. Principal component analysis showed an 89% variance for PC1 and PC2. K-mean clustering explained 77.4% of the variance in the data and grouped the accessions into three clusters. All six root traits had greater coefficients of variation (≥15%) among the tested accessions. Furthermore, to determine which root traits best distinguished different accessions, the correlation within our set of accessions provided trait-based ranking depending on their contribution. The identified accessions may be advantageous for the development of new crossing combinations to improve root features in adzuki beans during the early growth stage. The root traits assessed in this study could be attributes for future adzuki bean crop selection and improvement.

High-Throughput Phenotypic Characterization and Diversity Analysis of Soybean Roots (Glycine max L.)

“…RMTs, can therefore serve a number of purposes, including seggregation of plants and prediction of yield, which can be very useful for breeding. Statistical analysis of our data using ANOVA indicated that our results showed a clear seggregation of germplasms compared to previous research conducted using the same methods [ 13 , 14 ]. In our study, all eight RMTs were found to be significantly different between the germplasms, and there was homogenecity among the three replications within each accession, whereas the previous study indicated two RMTs to be significantly variable across the studied germplasms ( Table 2 ) [ 13 , 14 ].…”

“…Statistical analysis of our data using ANOVA indicated that our results showed a clear seggregation of germplasms compared to previous research conducted using the same methods [ 13 , 14 ]. In our study, all eight RMTs were found to be significantly different between the germplasms, and there was homogenecity among the three replications within each accession, whereas the previous study indicated two RMTs to be significantly variable across the studied germplasms ( Table 2 ) [ 13 , 14 ]. In the present experiment, soybeans were grown in fields for two consecutive years (2019–2020), heterogeneous germplasms within accessions were removed according to agronomic characteristics (UPOV guidelines), and resources with a high seed vitality, as well as uniformity, were used.…”

“…For this reason, we used polyvinyl chloride (PVC) columns, which have been used by several researchers previously [ 13 ]. The quantity of data collected using traditional methods was highly limited compared to the newer methods that can carry out two-dimensional analysis of high-resolution images using software packages [ 14 , 15 ]. Further developments have also been made, but the 2D analysis of RMTs remains a comparatively cheap and efficient mode of plant phenotyping.…”

“…Across the studied accessions, a high coefficient of variation (CV) of more than 30% was observed for LABA, NF, and NT, indicating they were the most diverse RMTs and can be used to observe difference aross the accessions. A root phenome study among wild adzuki beans showed that highest CV among the RMTs were found to be NT (59.37%), SA (56.42%), and LENGTH (51.91%) [ 14 ]. In another study on mungbeans, root volume (RV) and root tips or number of tips (RT/NT) showed high CV among the studied population [ 16 ].…”

“…Trends in such RMT correlations can help to understand the overall root development. Although, some reports exist where some RMTs exhibited contrasting trends [ 14 ]. This becomes much more complex when we start comparing across other crop plants [ 14 ].…”