Molecular Characterization of Mg-Chelatase CHLI Subunit in Pea (Pisum sativum L.)

Abstract

As a rate-limiting enzyme for chlorophyll biosynthesis, Mg-chelatase is a promising target for improving photosynthetic efficiency. It consists of CHLH, CHLD, and CHLI subunits. In pea (Pisum sativum L.), two putative CHLI genes (PsCHLI1 and PsCHLI2) were revealed recently by the whole genome sequencing, but their molecular features are not fully characterized. In this study, PsCHLI1 and PsCHLI2 cDNAs were identified by PCR-based cloning and sequencing. Phylogenetic analysis showed that PsCHLIs were derived from an ancient duplication in legumes. Both PsCHLIs were more highly expressed in leaves than in other organs and downregulated by abscisic acid and heat treatments, while PsCHLI1 was more highly expressed than PsCHLI2. PsCHLI1 and PsCHLI2 encode 422- and 417-amino acid proteins, respectively, which shared 82% amino acid identity and were located in chloroplasts. Plants with a silenced PsCHLI1 closely resembled PsCHLI1 and PsCHLI2 double-silenced plants, as both exhibited yellow leaves with barely detectable Mg-chelatase activity and chlorophyll content. Furthermore, plants with a silenced PsCHLI2 showed no obvious phenotype. In addition, the N-terminal fragment of PsCHLI1 (PsCHLI1N, Val63-Cys191) and the middle fragment of PsCHLI1 (PsCHLI1M, Gly192-Ser336) mediated the formation of homodimers and the interaction with CHLD, respectively, while active PsCHLI1 was only achieved by combining PsCHLI1N, PsCHLI1M, and the C-terminal fragment of PsCHLI1 (Ser337-Ser422). Taken together, PsCHLI1 is the key CHLI subunit, and its peptide fragments are essential for maintaining Mg-chelatase activity, which can be used to improve photosynthetic efficiency by manipulating Mg-chelatase in pea.

Magnesium chelatase subunit D is not only required for chlorophyll biosynthesis and photosynthesis, but also affecting starch accumulation in Manihot esculenta Crantz

“…6c). These changes observed in this study were consistent with previous studies on VIGS in Mg-chelatase subunits [17,19,30]. Furthermore, these changes in chlorophyll biosynthesis signi cantly correlated with reduced the expression level of photosynthesis-related genes (Fig.…”

“…4). Similar results were observed in other Mg-chelatase subunits of different plant species [17,19,40], where it is suggested that these subunits involved in Chlorophyll biosynthesis. In addition, Y2H assay indicated that MeChlD interacts with MeChlM, MePrxQ (Fig.…”

“…Magnesium chelatase consists of at least three different subunits, ChlI, ChlH and ChlD subunits [8]. These subunits have been reported in plants, especially in Oryza sativa [9][10][11], Nicotiana benthamiana [12,13], Arabidopsis thaliana [14,15], Glycine max [16-18], Pisum sativum [19], Zea mays [20], which have speci c functions in chlorophyll biosynthesis and photosynthesis. AtChlH protein involves in plastid-to-nucleus signal transduction [21,22].…”

Morpho-Physiological and Anatomical Alterations of Salt-Affected Thompson Seedless Grapevine (Vitis vinifera L.) to Brassinolide Spraying

“…The ability of BL to maintain plasma membrane structure may have been associated with the considerable reduction in Na + and the enhancement of K + ions [74]. Salinity tolerance accomplished by BRs amendment is possibly ascribed to its capability to enhance K + uptake and restrict Na + concentration into xylem, while sustaining an elevated K + /Na + ratio in plant tissues [27,75]. This is possibly owing to the overexpression of salt overly sensitive 1 (SOS1, Na + /H + antiporter), which shifts extra Na + outside the cytosol and assists preserve small cytosolic Na + levels in tissues, particularly in root epidermal cells and root tips [76].…”

A paler shade of green: engineering cellular chlorophyll content to enhance photosynthesis in crowded environments

“…This work is the first report of Chl content engineering in a crop with a strong potential for enhancing biomass accumulation in the production of renewable energy. Of note, members of the Fabaceae family, including G. max (Zhang et al ., 2018) and Pisum sativum (pea) (Wu et al ., 2022), possess several chlI , chlD and chlD paralogs in their genomes with slightly different transcriptional regulation and, possibly, function(s), thus offering a wider range of targets for engineering approaches.…”