EpiHLB: Deciphering (epi)genetic resistance mechanisms to HLB disease between Oceanian and Asian citrus intergeneric-hybrids

• Grant number: 23/03272-3
• Support Opportunities: Regular Research Grants
• Start date: February 01, 2024
• End date: January 31, 2028
• Field of knowledge: Agronomical Sciences - Agronomy - Plant Health
• Agreement: ANR
• Principal Investigator: Nelson Arno Wulff
• Grantee: Nelson Arno Wulff
• Principal researcher abroad: Barbara HUFNAGEL
• Institution abroad: Centre de Coopération Internationale en Recherche Agronomique pour le Développement (CIRAD), France
• Host Institution: Fundo de Defesa da Citricultura (FUNDECITRUS). Araraquara , SP, Brazil
• Associated researchers: Eliane Cristina Locali ; JUAN CAMILO CIFUENTES ARENAS ; Mônica Neli Alves ; Sílvio Aparecido Lopes
• Associated scholarship(s): 24/09984-8 - HLB resistance present in Oceanian Citrus relatives (Microcitrus and Eremocitrus) to improve Citrus breeding by using gene expression studies, BP.PD

Abstract

Citrus huanglongbing (HLB), or greening, is the most destructive citrus disease worldwide and is threatening the sustainability of the industry, affecting tree development, production and fruit quality. All Asian citrus species, including all commercial varieties, are susceptible to HLB, but tolerance and resistance have been described in some citrus relatives belonging to the Oceanian genera Microcitrus and Eremocitrus. The species of these genera are sexually compatibles with Citrus. CIRAD generated a unique diversity panel of diploid intergeneric-hybrids (Citrus sp. x Microcitrus sp.) over several generations. FUNDECITRUS, whilst, has generated several populations of intergeneric-hybrids (Citrus sp. x Microcitrus sp.) of first and second generation. Such wide crosses may result in non-Mendelian inheritance of phenotypic traits due to reformatting of the epigenetic landscape. The overall objective of the EpiHLB project is to identify genes and genomic regions associated to HLB resistance and searching how their expression is controlled. A core collection of intergeneric hybrids will be selected from CIRAD and FUNDECITRUS populations and their response to Candidatus Liberibacter asiaticus infection will be studied under HLB challenge inoculation stress. The project will focus on the role of genetic and epigenetic factors in the regulation of gene expression that are linked to HLB resistance, by developing a multi-omic quantitative approach, combining multiple layers of association studies. The strategy is to join genomic (GBS and WGS), transcriptomic (RNA-seq and small RNAseq) and epigenetic (Methylome) studies to the phenotype in order to develop models of omics-association. In the framework of the implementation of sustainable integrated pest management, the results of the project will contribute to the development and selection of innovative strategies to create cultivars and rootstocks resistant to this disease, severely affecting a worldwide socioeconomical important crop. (AU)