Loss of GLK1 transcription factor function reveals new insights in chlorophyll biosynthesis and chloroplast development

Abstract

Birch (Betula platyphylla × B. pendula) is an important tree for landscaping due to its attractive white bark and straight trunk. In this study, we characterized a T-DNA yellow-green leaf mutant, yl. We identified six insertion sites (ISs) in the mutant by genome resequencing and found a 40-kb deletion containing BpGLK1 around IS2 on chromosome 2. Complementation experiments with the yl mutant and repression of BpGLK1 in wild-type plants confirmed that BpGLK1 was responsible for the mutated phenotype. Physiological and ultrastructural analyses showed that the leaves of the yl mutant and BpGLK1-repression lines had decreased chlorophyll content and defective chloroplast development compared to the wild-type. Furthermore, the loss function of BpGLK1 also affected photosynthesis in leaves. Transcriptomics, proteomics, and ChIP-PCR analysis revealed that BpGLK1 directly interacted with the promoter of genes related to antenna proteins, chlorophyll biosynthesis, and photosystem subunit synthesis, and regulated their expression. Overall, our research not only provides new insights into the mechanism of chloroplast development and chlorophyll biosynthesis regulated by BpGLK1, but also provides new transgenic birch varieties with various levels of yellowing leaves by repressing BpGLK1 expression.

Characterization of the Poplar R2R3-MYB Gene Family and Over-Expression of PsnMYB108 Confers Salt Tolerance in Transgenic Tobacco

“…Gene duplication events play essential roles in formation of gene family ( Gang et al, 2019 ). Using TBtools and MCScanX methods, we examined the poplar R2R3 MYB genes for tandem duplication events ( Wang et al, 2012 ; Chen et al, 2020 ).…”

Metabolome and transcriptome analyses reveal chlorophyll and anthocyanin metabolism pathway associated with cucumber fruit skin color

“…Chlorophyll synthesis has been well studied and important related genes for chlorophyll synthesis have been found in leave and fruits [8,28]. Gang et al [29] found that BpGLK1 the function for decreased chlorophyll content and defective chloroplast development by physiological and ultrastructural analysis. In addition, many key genes of coding enzymes were involved in chlorophyll synthesis pathway, such as HemA, HemB, chlH, chlM, por, NOL [3,4].…”

Comparative Transcriptomics Provides Insight into Rind Color Polymorphism in Watermelon

“…Yin found that transient and stable overexpression of CitERF13 resulted in rapid chlorophyll degradation in Nicotiana tabacum leaves and made leaves yellow. Expression of the gene CitERF13 sharply increases, and the fruit color also changes to yellow with ethylene treatment [34]. Except for the unigene TRINITY_DN39858_c0_g4, another transcription factor (TRINITY_DN41795_c0_g5) belonging to the MYB gene family with higher expression levels in material WT4 was also found (Fig.…”

“…For example, the R2R3-MYB transcription factor in kiwifruit (Actinidia deliciosa) was observed to modulate chlorophyll and carotenoid accumulation by activating the promoter of the kiwifruit lycopene betacyclase (AdLCY-β) gene, which plays a key role in the carotenoid biosynthetic pathway [33]. In birch, the GLK1 transcription factor directly interacts with the promoter of genes related to antenna protein, chlorophyll biosynthesis, and photosystem subunit synthesis and regulates their expression, thereby further affecting chloroplast development [34]. In the present study, the main reason for carrying out a de novo assembly of the transcriptome is to screen for the gene responsible for the yellow rind of watermelon that may not be assembled into the watermelon reference genome of cultivar 97103.…”