Chloroplastic pentatricopeptide repeat proteins (PPR) in albino plantlets of Agave angustifolia Haw. reveal unexpected behavior

Abstract

Background Pentatricopeptide repeat (PPR) proteins play an essential role in the post-transcriptional regulation of genes in plastid genomes. Although important advances have been made in understanding the functions of these genes, there is little information available on chloroplastic PPR genes in non-model plants and less in plants without chloroplasts. In the present study, a comprehensive and multifactorial bioinformatic strategy was applied to search for putative PPR genes in the foliar and meristematic tissues of green and albino plantlets of the non-model plant Agave angustifolia Haw. Results A total of 1581 PPR transcripts were identified, of which 282 were chloroplastic. Leaf tissue in the albino plantlets showed the highest levels of expression of chloroplastic PPRs. The search for hypothetical targets of 12 PPR sequences in the chloroplast genes of A. angustifolia revealed their action on transcripts related to ribosomes and translation, photosystems, ATP synthase, plastid-encoded RNA polymerase and RuBisCO. Conclusions Our results suggest that the expression of PPR genes depends on the state of cell differentiation and plastid development. In the case of the albino leaf tissue, which lacks functional chloroplasts, it is possible that anterograde and retrograde signaling networks are severely compromised, leading to a compensatory anterograde response characterized by an increase in the expression of PPR genes.

Physiological, Photosynthetic, and Transcriptomics Insights into the Influence of Shading on Leafy Sweet Potato

“…The splicing process of introns affects the translation of chloroplast genes, and it is related to the assembly of photosystem complexes, thereby affecting photosynthesis [68,69]. The splicing factors include PPR proteins, CRM domain proteins, and the mTERF protein family [70][71][72][73]. Chlorophyll levels fluctuated significantly under low-light environments, as their biosynthesis required the participation of catalytic enzyme genes, such as CHLI and PPOX, which were highly expressed in the present study [74,75].…”

Transcriptome analysis reveals molecular mechanisms underlying chloroplast biogenesis in albino Agave angustifolia plantlets

“…This over‐expression of PPR genes could potentially signify a retro‐anterograde compensatory response attempting to rectify the blockage in plastid biogenesis. Nonetheless, this response seems insufficient to alter the undifferentiated state of the plastid and reverse albinism (Andrade‐Marcial et al, 2022).…”

“…Our research indicates that variations in DNA methylation patterns during subculturing may contribute to the development of the albino condition in these plants. Despite advancements in delineating the structural and physiological anomalies of albino plantlets (Duarte‐Aké et al, 2016; Us‐Camas et al, 2017; Hernández‐Castellano et al, 2020; Duarte‐Aké & De‐la‐Peña, 2021; Andrade‐Marcial et al, 2022; Andrade‐Marcial et al, 2023), the primary causes at the genetic and molecular levels, particularly those influencing the signaling pathways of chloroplast biogenesis, remain to be fully elucidated.…”

Development and Investigation of HRM Markers to Discriminate Two Ogura Cytoplasmic Male Sterility Restorer Genes in Radish

“…Evidence suggests that PPR proteins are involved in the post-transcriptional regulation of chloroplast and mitochondrial genes, including RNA maturation, editing, intron splicing, transcript stabilization, and translation initiation. The synergy of RNA metabolism has profound effects on the biogenesis and function of both chloroplasts and mitochondria, influencing processes such as photosynthesis, respiration, development, and environmental responses in plants [20,22,23]. The male sterility recovery gene likely evolved through numerous interactions with the host in the symbiotic relationship with mitochondria.…”