Biology subjects

Arra, Y.

Publications and source records attributed to Arra, Y..

5 recordsLinked to original sources

bioRxiv2026

Pyramiding four genes governing bacterial blight resistance in three popular rice varieties of East Africa and Madagascar

Bacterial blight of rice causes substantial crop losses in Asia and Africa. The recent introduction of Asian strains into African countries has led to two independent outbreaks detected in 2019, causing severe damage in Madagascar and Tanzania. The strains are highly virulent on local rice varieties and rapidly spread from Tanzania to neighboring countries. Multiplex genome editing of effector-binding elements in the promoter of SWEET rice promoters has successfully generated elite rice lines with broad-spectrum resistance against bacterial blight. While genome-edited crops can be released in countries with biosafety regulations, their use in countries that have yet to establish regulations, e.g., Tanzania and Madagascar, is hindered. To circumvent this, marker-assisted backcross breeding (MABB) of the African elite varieties Komboka, FARO-44, and NE-RICA-4 was adopted to introgress resistance genes to confer resistance to Xoo strains identified in Tanzania (iTz) and Madagascar (iMg). Resistance gene pyramiding, namely Xa1, Xa4, xa13, and Xa21, in the three elite rice varieties conferred resistance to iTz and iMg strains. Our study presents a solution to provide rice breeders in East Africa with bacterial blight resistance in three local rice varieties for field trials, line registration, and deployment.

Plant Biology↗

bioRxiv2025

Restricted transmission of Xanthomonas oryzae pv. oryzae from rice roots to shoots detected by a rapid root infection system

Xanthomonas oryzae pv. oryzae (Xoo), the causal agent of bacterial blight in rice, is primarily studied in the context of foliar infections. However, infected stubble and irrigation water may serve as reservoirs and be responsible for seedling stage root infections in the field, especially during transplanting. Here, we established a coleoptile crown root-based infection protocol to investigate whether gene-for-gene interactions between Xoo TAL effectors and SWEET sucrose uniporter susceptibility genes occur in the root xylem, and whether the disease can propagate from roots to seedling shoots. Using translational SWEET11a-GUS reporter lines under control of the native SWEET11a promoter, we observed progressive infection as indicated by accumulation of SWEET11a-GUS fusion protein in infected coleoptile crown roots. However, we did not detect progression of GUS accumulation beyond the coleoptile node, nor did we detect blight symptoms on the young leaves. Notably, the xylem, at least during early stages of infection remained functional as shown by Rhodamine B tracer, consistent with transfer of xylem constituents via living cells at the coleoptile node that did not allow bacteria to pass. Furthermore, the root infection protocol is a [~]4x faster compared to standard leaf-clipping assays (roots assay: 11 days from sowing, compared to 39 days for clip infection), enabling more rapid assessment of TAL effector repertoire and plant defense responses with translational SWEET-GUS reporter lines. Our findings expand our understanding of Xoo infection routes and provide a valuable tool for resistance testing and pathogen surveillance.

plant biology↗

bioRxiv2023

Rice Yellow Mottle Virus resistance by genome editing of the Oryza sativa L. ssp. japonica nucleoporin gene OsCPR5.1 but not OsCPR5.2

Rice yellow mottle virus (RYMV) causes one of the most devastating rice diseases in Africa. Management of RYMV is challenging. Genetic resistance provides the most effective and environment-friendly control. The recessive resistance locus rymv2 (OsCPR5.1) had been identified in African rice (O. glaberrima), however, introgression into O. sativa ssp. japonica and indica remains challenging due to crossing barriers. Here, we evaluated whether CRISPR/Cas9 genome editing of the two rice nucleoporin paralogs OsCPR5.1 (RYMV2) and OsCPR5.2 can be used to introduce RYMV resistance into the japonica variety Kitaake. Both paralogs had been shown to complement the defects of the Arabidopsis atcpr5 mutant, indicating partial redundancy. Despite striking sequence and structural similarities between the two paralogs, only oscpr5.1 loss-of-function mutants were fully resistant, while loss-of-function oscpr5.2 mutants remained susceptible, intimating that OsCPR5.1 plays a specific role in RYMV susceptibility. Notably, edited lines with short in-frame deletions or replacements in the N-terminal domain (predicted to be unstructured) of OsCPR5.1 were hypersusceptible to RYMV. In contrast to mutations in the single Arabidopsis AtCPR5 gene, which caused severely dwarfed plants, oscpr5.1 and oscpr5.2 single knockout mutants show neither substantial growth defects nor symptoms indicative of programmed cell death, possibly reflecting functional redundancy of the isoforms regarding other important functions. The specific editing of OsCPR5.1, while maintaining OsCPR5.2 activity, provides a promising strategy for generating RYMV-resistance in elite Oryza sativa lines as well as for effective stacking with other RYMV resistance genes or other traits.

plant biology↗

bioRxiv2022

Genome editing of an African elite rice variety confers resistance against endemic and emerging Xanthomonas oryzae pv. oryzae strains

Bacterial leaf blight (BB) of rice, caused by Xanthomonas oryzae pv. oryzae (Xoo), threatens global food security and the livelihood of small-scale rice producers. Analyses of Xoo collections from Asia, Africa and the Americas demonstrated surprising continental segregation, despite robust global rice trade. Here, we report unprecedented BB outbreaks in Tanzania. The causative strains, unlike endemic Xoo, carry Asian-type TAL effectors targeting the sucrose transporter SWEET11a and suppressing Xa1. Phylogenomics clustered these strains with Xoo strains from China. African rice varieties do not carry suitable resistance genes. To protect African rice production against this emerging threat, we developed a hybrid CRISPR-Cas9/Cpf1 system to edit six TALe-binding elements in three SWEET promoters of the East African elite variety Komboka. The edited lines show broad-spectrum resistance against Asian and African strains of Xoo, including strains recently discovered in Tanzania. This strategy could help to protect global rice crops from BB pandemics.

plant biology↗

bioRxiv2021

Sucrose-dependence of sugar uptake, quorum sensing and virulence of the rice blight pathogen Xanthomonas oryzae pv. oryzae

Withdrawal StatementThe authors have withdrawn their manuscript owing to potential issues with the qRT-PCR data and issues with accessing some of the raw data from one of the authors (FAIR principle requirements). Therefore, the authors do not wish this work to be cited as reference for the project. If you have any questions, please contact the corresponding author.

plant biology↗