RGB image-based method for phenotyping rust disease progress in pea leaves using R

Abstract Background Rust is a damaging disease affecting vital crops, including pea, and identifying highly resistant genotypes remains a challenge. Accurate measurement of infection levels in large germplasm collections is crucial for finding new resistance sources. Current evaluation methods rely...

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Main Authors: Salvador Osuna-Caballero, Tiago Olivoto, Manuel A. Jiménez-Vaquero, Diego Rubiales, Nicolas Rispail
Format: Article
Language:English
Published: BMC 2023-08-01
Series:Plant Methods
Subjects:
Online Access:https://doi.org/10.1186/s13007-023-01069-z
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author Salvador Osuna-Caballero
Tiago Olivoto
Manuel A. Jiménez-Vaquero
Diego Rubiales
Nicolas Rispail
author_facet Salvador Osuna-Caballero
Tiago Olivoto
Manuel A. Jiménez-Vaquero
Diego Rubiales
Nicolas Rispail
author_sort Salvador Osuna-Caballero
collection DOAJ
description Abstract Background Rust is a damaging disease affecting vital crops, including pea, and identifying highly resistant genotypes remains a challenge. Accurate measurement of infection levels in large germplasm collections is crucial for finding new resistance sources. Current evaluation methods rely on visual estimation of disease severity and infection type under field or controlled conditions. While they identify some resistance sources, they are error-prone and time-consuming. An image analysis system proves useful, providing an easy-to-use and affordable way to quickly count and measure rust-induced pustules on pea samples. This study aimed to develop an automated image analysis pipeline for accurately calculating rust disease progression parameters under controlled conditions, ensuring reliable data collection. Results A highly efficient and automatic image-based method for assessing rust disease in pea leaves was developed using R. The method’s optimization and validation involved testing different segmentation indices and image resolutions on 600 pea leaflets with rust symptoms. The approach allows automatic estimation of parameters like pustule number, pustule size, leaf area, and percentage of pustule coverage. It reconstructs time series data for each leaf and integrates daily estimates into disease progression parameters, including latency period and area under the disease progression curve. Significant variation in disease responses was observed between genotypes using both visual ratings and image-based analysis. Among assessed segmentation indices, the Normalized Green Red Difference Index (NGRDI) proved fastest, analysing 600 leaflets at 60% resolution in 62 s with parallel processing. Lin’s concordance correlation coefficient between image-based and visual pustule counting showed over 0.98 accuracy at full resolution. While lower resolution slightly reduced accuracy, differences were statistically insignificant for most disease progression parameters, significantly reducing processing time and storage space. NGRDI was optimal at all time points, providing highly accurate estimations with minimal accumulated error. Conclusions A new image-based method for monitoring pea rust disease in detached leaves, using RGB spectral indices segmentation and pixel value thresholding, improves resolution and precision. It rapidly analyses hundreds of images with accuracy comparable to visual methods and higher than other image-based approaches. This method evaluates rust progression in pea, eliminating rater-induced errors from traditional methods. Implementing this approach to evaluate large germplasm collections will improve our understanding of plant-pathogen interactions and aid future breeding for novel pea cultivars with increased rust resistance.
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spelling doaj.art-693b4b7c4a1d4e4d872ccc8c23e1c7122023-11-26T13:26:51ZengBMCPlant Methods1746-48112023-08-0119111410.1186/s13007-023-01069-zRGB image-based method for phenotyping rust disease progress in pea leaves using RSalvador Osuna-Caballero0Tiago Olivoto1Manuel A. Jiménez-Vaquero2Diego Rubiales3Nicolas Rispail4Institute for Sustainable Agriculture, CSICDepartment of Plant Science, Federal University of Santa CatarinaInstitute for Sustainable Agriculture, CSICInstitute for Sustainable Agriculture, CSICInstitute for Sustainable Agriculture, CSICAbstract Background Rust is a damaging disease affecting vital crops, including pea, and identifying highly resistant genotypes remains a challenge. Accurate measurement of infection levels in large germplasm collections is crucial for finding new resistance sources. Current evaluation methods rely on visual estimation of disease severity and infection type under field or controlled conditions. While they identify some resistance sources, they are error-prone and time-consuming. An image analysis system proves useful, providing an easy-to-use and affordable way to quickly count and measure rust-induced pustules on pea samples. This study aimed to develop an automated image analysis pipeline for accurately calculating rust disease progression parameters under controlled conditions, ensuring reliable data collection. Results A highly efficient and automatic image-based method for assessing rust disease in pea leaves was developed using R. The method’s optimization and validation involved testing different segmentation indices and image resolutions on 600 pea leaflets with rust symptoms. The approach allows automatic estimation of parameters like pustule number, pustule size, leaf area, and percentage of pustule coverage. It reconstructs time series data for each leaf and integrates daily estimates into disease progression parameters, including latency period and area under the disease progression curve. Significant variation in disease responses was observed between genotypes using both visual ratings and image-based analysis. Among assessed segmentation indices, the Normalized Green Red Difference Index (NGRDI) proved fastest, analysing 600 leaflets at 60% resolution in 62 s with parallel processing. Lin’s concordance correlation coefficient between image-based and visual pustule counting showed over 0.98 accuracy at full resolution. While lower resolution slightly reduced accuracy, differences were statistically insignificant for most disease progression parameters, significantly reducing processing time and storage space. NGRDI was optimal at all time points, providing highly accurate estimations with minimal accumulated error. Conclusions A new image-based method for monitoring pea rust disease in detached leaves, using RGB spectral indices segmentation and pixel value thresholding, improves resolution and precision. It rapidly analyses hundreds of images with accuracy comparable to visual methods and higher than other image-based approaches. This method evaluates rust progression in pea, eliminating rater-induced errors from traditional methods. Implementing this approach to evaluate large germplasm collections will improve our understanding of plant-pathogen interactions and aid future breeding for novel pea cultivars with increased rust resistance.https://doi.org/10.1186/s13007-023-01069-zDisease resistanceImage analysisPeaPhenotypingPhytopathometryRust
spellingShingle Salvador Osuna-Caballero
Tiago Olivoto
Manuel A. Jiménez-Vaquero
Diego Rubiales
Nicolas Rispail
RGB image-based method for phenotyping rust disease progress in pea leaves using R
Plant Methods
Disease resistance
Image analysis
Pea
Phenotyping
Phytopathometry
Rust
title RGB image-based method for phenotyping rust disease progress in pea leaves using R
title_full RGB image-based method for phenotyping rust disease progress in pea leaves using R
title_fullStr RGB image-based method for phenotyping rust disease progress in pea leaves using R
title_full_unstemmed RGB image-based method for phenotyping rust disease progress in pea leaves using R
title_short RGB image-based method for phenotyping rust disease progress in pea leaves using R
title_sort rgb image based method for phenotyping rust disease progress in pea leaves using r
topic Disease resistance
Image analysis
Pea
Phenotyping
Phytopathometry
Rust
url https://doi.org/10.1186/s13007-023-01069-z
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