Genetius

The study tested combined antibiotic and callose inhibitor treatments to restore phloem function and improve carbon allocation in HLB‑affected citrus. While the callose inhibitor alone boosted short‑term sugar transport and the antibiotic alone increased fruit carbon import, only the combined treatment consistently reduced callose blockage, enhanced phloem conductivity, lowered fruit abscission, and raised total fruit carbon after drop. These results indicate that targeting both pathogen load and host callose accumulation is needed to rebalance source‑sink dynamics and boost orchard productivity.

The study investigated gene expression, DNA methylation, and small RNA profiles in a Citrus hybrid derived from C. reticulata and C. australasica, revealing allele‑specific expression and asymmetric CHH methylation reprogramming, especially increased CHH methylation on the C. australasica subgenome. Unexpectedly, CHH methylation correlated with higher gene expression and abundant 24‑nt small RNAs at promoters, suggesting RdDM may activate transcription in citrus fruit. The work provides a pipeline for analyzing epigenetic regulation in complex hybrids, aiding future disease‑resistant cultivar development.

The study identified direct downstream targets of the citrus susceptibility transcription factor CsLOB1, showing that the expansin gene CsEXP2 and the endoglucanase gene CsEG1 are activated via the Xanthomonas citri TALE PthA4‑CsLOB1 pathway and can induce canker‑like symptoms. Using dTALE constructs in a Xcc mutant, the authors demonstrated that targeting these genes restores water soaking and pustule formation, linking them to disease development.