Project description:Citrus canker caused by Xanthomonas citri subsp. citri (Xcc) is one of the most devastating diseases in citrus industry worldwide. Most citrus cultivars such as sweet orange are susceptible to canker disease. Here, we utilized wild citrus to identify canker-resistant germplasms, and found that Atalantia buxifolia, a primitive (distant-wild) citrus, exhibited remarkable resistance to canker disease. Although the susceptibility gene LATERAL ORGAN BOUNDARIES 1 (LOB1) could also be induced in Atalantia after canker infection, the induction extent was far lower than that in sweet orange. In addition, three of amino acids encoded by transcription factor TFIIAγ in Atalantia (AbTFIIAγ) exhibited difference from those in sweet orange (CsTFIIAγ) which could stabilize the interaction between effector PthA4 and effector binding element (EBE) of LOB1 promoter. The mutation of AbTFIIAγ did not change its interaction with transcription factor binding motifs (TFBs). However, the AbTFIIAγ could hardly support the LOB1 expression induced by the PthA4. In addition, the activity of AbLOB1 promoter was significantly lower than that of CsLOB1 under the induction by PthA4. Our results demonstrate that natural variations of AbTFIIAγ and effector binding element (EBE) in the AbLOB1 promoter are crucial for the canker disease resistance of Atalantia. The natural mutations of AbTFIIAγ gene and AbLOB1 promoter in Atalantia provide candidate targets for improving the resistance to citrus canker disease.
Project description:In this study, we have characterized a putative chloroplast ribosome assembly factor. To elucidate transcriptional responses caused by decreased chloroplast function, we have measured the transcriptome of wild-type and knock-down seedlings.
Project description:We found that thylakoid-anchored protein PBF8 is a key regulator for Photosystem I (PSI) biogenesis. To explore the role of PBF8 in regulating chloroplast gene expression, we performed the RNA-seq to compare the the transcript levels of chloroplast-encoded genes between wild type (Col-0) and pbf8 mutants. To this end, we isolated the total RNA form 12-day-old wild type and pbf8 seedlings grown on the MS medium under long-day conditions (14 h light, 10 h dark) at 22 ºC and with a light intensity of 80 µmol m-2 s-1. The rRNAs were deleted using the Ribo-Zero Kit (Epicentre). The resulting rRNA-depleted RNA was used for preparing the sequencing library with NEBNext Single Cell/Low input library Prep Kit. The libraries were pooled and sequenced on an Illumina Nova 6000 system with 150-bp pair-end reads. Finally, our results show that the transcript accumulation for chloroplast-encoded PSI subunit and assembly factor genes between the wild type (Col-0) and pbf8 samples, suggesting PBF8 may not affect the transcript levels of chloroplast-encoded PSI subunits and assembly factors in chloroplasts.
Project description:The coordination of chloroplast and nuclear genome status are critical for plant cell function, but the mechanism remain largely unclear. In this study, we report that Arabidopsis thaliana CHLOROPLAST AND NUCLEUS DUAL-LOCALIZED PROTEIN 1 (CND1) maintains genome stability in both the chloroplast and the nucleus.