bims-plasge 2023-12-31 papers

Issue of 2023–12–31
two papers selected by
Vera S. Bogdanova, ИЦиГ СО РАН

Ann Bot. 2023 Dec 23. pii: mcad196. [Epub ahead of print]

Paternal leakage of plastids rescues inter-lineage hybrids in Silene nutans.

Zoé Postel, Fabienne Van Rossum, Cécile Godé, Eric Schmitt, Pascal Touzet.

BACKGROUND AND AIMS: Organelle genomes are usually maternally inherited in angiosperms. However, biparental inheritance has been observed, especially in hybrids resulting from crosses between divergent genetic lineages. When it concerns the plastid genome, this exceptional mode of inheritance might rescue inter-lineage hybrids suffering from plastid-nuclear incompatibilities. Genetically differentiated lineages of Silene nutans exhibit strong post-zygotic isolation due to plastid-nuclear incompatibilities, highlighted by inter-lineage hybrid chlorosis and mortality. Surviving hybrids can exhibit variegated leaves, which might indicate paternal leakage of the plastid genome. We tested whether the surviving hybrids inherited the paternal plastid genome and survived thanks to paternal leakage.
METHODS: We characterized leaf phenotype (fully green, variegated or white) of 504 surviving inter-lineage hybrids obtained from a reciprocal cross experiment among populations of four genetic lineages (W1, W2, W3 and E1) of S. nutans from Western Europe, and genotyped 560 leaf samples (both green and white leaves for variegated hybrids) using six lineage-specific plastid SNPs.
KEY RESULTS: A high proportion of the surviving hybrids (up to 98%) inherited the paternal plastid genome, indicating paternal leakage. The level of paternal leakage depended on cross type and cross direction. E1 and W2 lineages as maternal lineages led to the highest hybrid mortality and to the highest paternal leakage from W1 and W3 lineages in the few surviving hybrids. This was consistent with E1 and W2 lineages, which contained the most divergent plastid genomes. When W3 was the mother, more hybrids survived, and no paternal leakage was detected.
CONCLUSIONS: By providing a plastid genome potentially more compatible with the hybrid nuclear background, paternal leakage has the potential to rescue inter-lineage hybrid from plastid-nuclear incompatibilities. Doing so, this phenomenon might slow down the speciation process - provided hybrid survival and reproduction can occur in the wild.

Keywords: Silene nutans ; inter-lineage hybrids; paternal leakage; plastid genome; plastid-nuclear incompatibilities; reproductive isolation; variegated leaf phenotype

DOI: https://doi.org/10.1093/aob/mcad196

Physiol Plant. 2023 Nov-Dec;175(6):175(6): e14062

Genome-wide transcriptional responses to water deficit during seed development in Pisum sativum, focusing on sugar transport and metabolism.

Amélie Morin, Benoit Porcheron, Gatepe Cedoine Kodjovi, Bouziane Moumen, Cécile Vriet, Laurence Maurousset, Rémi Lemoine, Nathalie Pourtau, Joan Doidy.

Agriculture is particularly impacted by global changes, drought being a main limiting factor of crop production. Here, we focus on pea (Pisum sativum), a model legume cultivated for its seed nutritional value. A water deficit (WD) was applied during its early reproductive phase, harvesting plant organs at two key developmental stages, either at the embryonic or the seed-filling stages. We combined phenotypic, physiological and transcriptome analyses to better understand the adaptive response to drought. First, we showed that apical growth arrest is a major phenotypic indicator of water stress. Sugar content was also greatly impacted, especially leaf fructose and starch contents. Our RNA-seq analysis identified 2001 genes regulated by WD in leaf, 3684 genes in root and 2273 genes in embryonic seed, while only 80 genes were regulated during seed-filling. Hence, a large transcriptional reprogramming occurred in response to WD in seeds during early embryonic stage, but no longer during the later stage of nutritional filling. Biological processes involved in transcriptional regulation, carbon transport and metabolism were greatly regulated by WD in both source and sink organs, as illustrated by the expression of genes encoding transcription factors, sugar transporters and enzymes of the starch synthesis pathway. We then looked at the transcriptomic changes during seed development, highlighting a transition from monosaccharide utilization at the embryonic stage to sucrose transport feeding the starch synthesis pathway at the seed-filling stage. Altogether, our study presents an integrative picture of sugar transport and metabolism in response to drought and during seed development at a genome-wide level.

DOI: https://doi.org/10.1111/ppl.14062