HLB resistance present in Oceanian Citrus relatives (Microcitrus and Eremocitrus) to improve Citrus breeding by using gene expression studies

• Grant number: 24/09984-8
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• Start date: April 01, 2025
• End date: March 31, 2028
• Field of knowledge: Agronomical Sciences - Agronomy - Plant Health
• Principal Investigator: Nelson Arno Wulff
• Grantee: Leny Yann Renat Calvez
• Host Institution: Fundo de Defesa da Citricultura (FUNDECITRUS). Araraquara , SP, Brazil
• Associated research grant: 23/03272-3 - EpiHLB: Deciphering (epi)genetic resistance mechanisms to HLB disease between Oceanian and Asian citrus intergeneric-hybrids, AP.R

Abstract

Huanglongbing (HLB), also known as citrus greening disease, is a highly destructive disease affecting citrus trees worldwide. The causal agent (by association) of the disease is the bacterium Candidatus Liberibacter asiaticus which is transmitted by the Asian citrus psyllid, Diaphorina citri. There is no cure to HLB, the disease has considerable impact on tree growth and development, as well as on fruit yield and quality, leading the destruction of orchards and resulting in serious economic losses. In Brazil, millions of trees have been eradicated since 2004, to control the disease, however the incidence continues to rise each year, reaching 38% of trees in the citrus belt in 2023. Citrus breeding programs are the most sustainable, long-term solution to the development of HLB-resistant citrus varieties. Some wild Oceanian Citrus relatives have been identified as more or less resistant to HLB. These are Microcitrus and Eremocitrus species, which are sexually compatible with cultivated Citrus. Therefore, such wild, HLB-resistant Oceanian species are promising genotypes for such programs. Many hybrids resulted from the sexual hybridization between Microcitrus/Eremocitrus and commercial Citrus have been generated in an international effort to develop such a strategy. In this project, it is proposed to perform experimental inoculation, phenotypic screening, genomic and transcriptomic analysis to evaluate the hybrids populations for their HLB resistance and to better understand the genetic and molecular basis of HLB resistance present in Oceanian Citrus relatives.