Comparative transcriptome analysis identified ChlH and POLGAMMA2 in regulating yellow-leaf coloration in Forsythia

Abstract

Leaf color is one of the most important features for plants used for landscape and ornamental purposes. However, the regulatory mechanism of yellow leaf coloration still remains elusive in many plant species. To understand the complex genetic mechanism of yellow-leaf Forsythia, we first compared the pigment content and leaf anatomical structure of yellow-leaf and green-leaf accessions derived from a hybrid population. The physiological and cytological analyses demonstrated that yellow-leaf progenies were chlorophyll deficient with defected chloroplast structure. With comparative transcriptome analysis, we identified a number of candidate genes differentially expressed between yellow-leaf and green-leaf Forsythia plants. Among these genes, we further screened out two candidates, ChlH (magnesium chelatase Subunit H) and POLGAMMA2 (POLYMERASE GAMMA 2), with consistent relative-expression pattern between different colored plants. To verify the gene function, we performed virus-induced gene silencing assays and observed yellow-leaf phenotype with total chlorophyll content reduced by approximately 66 and 83% in ChlH-silenced and POLGAMMA2-silenced plants, respectively. We also observed defected chloroplast structure in both ChlH-silenced and POLGAMMA2-silenced Forsythia. Transient over-expression of ChlH and POLGAMMA2 led to increased chlorophyll content and restored thylakoid architecture in yellow-leaf Forsythia. With transcriptome sequencing, we detected a number of genes related to chlorophyll biosynthesis and chloroplast development that were responsive to the silencing of ChlH and POLGAMMA2. To summarize, ChlH and POLGAMMA2 are two key genes that possibly related to yellow-leaf coloration in Forsythia through modulating chlorophyll synthesis and chloroplast ultrastructure. Our study provided insights into the molecular aspects of yellow-leaf Forsythia and expanded the knowledge of foliage color regulation in woody ornamental plants.

Establishment of a Virus-Induced Gene-Silencing (VIGS) System in Passiflora edulis Sims and Its Use in the Functional Analysis of PechlH

“…The pTRV2-PechlH silencing vector was used to infect passion fruit seedlings and it was found that the infection could cause the newborn passion fruit leaves to lose their green colour and turn yellow. This finding is in line with those of previous studies [23][24][25]. In addition, the gene expression of the silenced gene group was significantly lower than that of the control group, as shown by qRT-PCR and other assays, and the expression of the PechlH gene was significantly suppressed.…”

Fine mapping and identifying candidate gene of Y underlying yellow peel in Cucurbita pepo

“…Although the large fragment duplication leads to the disruption of G11 and an increase in the copy number of G4, they showed little probability to be the causal gene for yellow peel, based on the expression level, functional annotation, and roles of their homologs in Arabidopsis. Meanwhile, CpCHLH encodes a subunit H of Mg-chelatase, and mutations in CHLH lead to an underdeveloped thylakoid member, low chlorophyll content, and a chlorosis phenotype in rice and other organisms (Goh et al, 2004;Li et al, 2022;Zhang et al, 2022). Interestingly, there are three transcripts related to CpCHLH in Y parental line, and two of them could be translated to gain-offunctional proteins.…”