Ectopic Transplastomic Expression of a Synthetic MatK Gene Leads to Cotyledon-Specific Leaf Variegation

Abstract

Chloroplasts (and other plastids) harbor their own genetic material, with a bacterial-like gene-expression systems. Chloroplast RNA metabolism is complex and is predominantly mediated by nuclear-encoded RNA-binding proteins. In addition to these nuclear factors, the chloroplast-encoded intron maturase MatK has been suggested to perform as a splicing factor for a subset of chloroplast introns. MatK is essential for plant cell survival in tobacco, and thus null mutants have not yet been isolated. We therefore attempted to over-express MatK from a neutral site in the chloroplast, placing it under the control of a theophylline-inducible riboswitch. This ectopic insertion of MatK lead to a variegated cotyledons phenotype. The addition of the inducer theophylline exacerbated the phenotype in a concentration-dependent manner. The extent of variegation was further modulated by light, sucrose and spectinomycin, suggesting that the function of MatK is intertwined with photosynthesis and plastid translation. Inhibiting translation in the transplastomic lines has a profound effect on the accumulation of several chloroplast mRNAs, including the accumulation of an RNA antisense to rpl33, a gene coding for an essential chloroplast ribosomal protein. Our study further supports the idea that MatK expression needs to be tightly regulated to prevent detrimental effects and establishes another link between leaf variegation and chloroplast translation.

Chloroplast Genome Sequences and Comparative Analyses of Combretaceae Mangroves with Related Species

“…The matK gene is always found to be located within the intron of the trnK gene ( Figure 1 ) same with some land plants [ 56 ]. MatK gene is identified to be essential for plant cell survival, and the expression of it needs to be tightly regulated to prevent detrimental effects and establishes another link between leaf variegation and chloroplast translation [ 57 ]. For the studies of plant systematics, the matK gene is the high selectively used gene as the DNA barcoding fragment for plants [ 58 ].…”

Endophytic Bacillus altitudinis Strain Uses Different Novelty Molecular Pathways to Enhance Plant Growth

“…Previously, maturase K gene expression was associated with developmental stage, etiolation, and regulation processes related with development and photosynthesis (Barthet and Hilu, 2007). Maturase K has influence in gene expression in plants and interferes with the proper expression of the photosynthetic mechanism (Qu et al, 2018). Indeed, the induction of the maturase K gene might have an effect on plant growth during the interaction, through an enhancing photosynthetic process.…”

Effect of UV‐B radiation on growth, flavonoid and podophyllotoxin accumulation, and related gene expression in Sinopodophyllum hexandrum

“…5). For the biological function of the four genes, MatK is a single splicing factor in the chloroplast, and its function is linked to photosynthesis and plastid translation (Hertel et al ., 2013; Qu et al ., 2018). The thylakoid Ndh complex transfers electrons from NADH to plastoquinone, and its activity is controlled by the NDH‐F subunit (Lascano et al ., 2003; Martín et al ., 2009).…”