Biology subjects

Strauss, S. H.

Publications and source records attributed to Strauss, S. H..

3 recordsLinked to original sources

bioRxiv2020

Vegetative phase change in Populus tremula x alba

O_LIPlants transition through juvenile and adult phases of vegetative development in a process known as vegetative phase change (VPC). In poplars (genus Populus) the differences between these stages are subtle, making it difficult to determine when this transition occurs. Previous studies of VPC in poplars have relied on plants propagated in vitro, leaving the natural progression of this process unknown. C_LIO_LIWe examined developmental morphology of seed-grown and in vitro derived Populus tremula x alba (clone 717-1B4), and compared the phenotype of these, to transgenics with manipulated miR156 expression, the master regulator of VPC. C_LIO_LIIn seed-grown plants, most traits changed from node-to-node during the first 3 months of development but remained constant after node 25. Many traits remained unchanged in clones over-expressing miR156, or were enhanced when miR156 was lowered, demonstrating their natural progression is regulated by the miR156/SPL pathway. The characteristic leaf fluttering of Populus is one of these miR156-regulated traits. C_LIO_LIVegetative development in plants grown from culture mirrored that of seed-grown plants, allowing direct comparison between plants often used in research and those found in nature. These results provide a foundation for further research on the role of VPC in the ecology and evolution of this economically important genus. C_LI

plant biology↗

bioRxiv2020

Hypomethylated poplars show higher tolerance to water deficit and highlight a dual role for DNA methylation in shoot meristem: regulation of stress response and genome integrity

As fixed and long living organisms subjected to repeated environmental stresses, trees have developed mechanisms such as phenotypic plasticity that help them to cope with fluctuating environmental conditions. Here, we tested the role DNA methylation as a hub of integration, linking plasticity and physiological response to water deficit in the shoot apical meristem of the model tree poplar (Populus). Using a reverse genetic approach, we compared hypomethylated RNAi-ddm1 lines to wild-type trees for drought tolerance. An integrative analysis was realized with phytohormone balance, methylomes, transcriptomes and mobilomes. Hypomethylated lines were more tolerant when subjected to moderate water deficit and were intrinsically more tolerant to drought-induced cavitation. The alteration of the DDM1 machinery induced variation in DNA methylation in a cytosine context dependent manner, both in genes and transposable elements. Hypomethylated lines subjected to water deficit showed altered expression of genes involved in phytohormone pathways, such as salicylic acid and modified hormonal balance. Several transposable elements showed stress- and/or line-specific patterns of reactivation, and we could detect copy number variations for two of them in stressed ddm1 lines. Overall, our data highlight two major roles for DNA methylation in the shoot apical meristem: control of stress response and plasticity through transduction of hormone signaling and maintenance of genome integrity through the control of transposable elements.

plant biology↗

bioRxiv2020

Hybrid origin of Populus tomentosa Carr. identified through genome sequencing and phylogenomic analysis

Populus tomentosa is widely distributed and cultivated in the Northern and Central China, where it is of great economic and ecological importance. However, the origin of P. tomentosa remains controversial. Here, we used a PacBio+Hi-C+Illumina strategy to sequence and assemble its 740.2 Mb (2n) genome. The assembly accounts for greater than 92.1% of the 800-megabase genome, comprises 38 chromosomes, and contains 59,124 annotated protein-coding genes. Phylogenomic analyses elucidated dynamic genome evolution events among its closely related white poplars, and revealed that tomentosa is comprised of two subgenomes, which we deomonstrate is likely to have resulted from hybridization between Populus adenopoda as the female, and Populus alba var. pyramidalis as the male, around 3.93 Mya. We also detected structural variations and allele-indels across genome. Our study presents a high quality and well assembled genome, unveils the origin of the widely distributed and planted P. tomentosa, and provides a powerful resource for comparative plant biology, breeding, and biotechnology.

genomics↗