Tapping into the plasticity of plant architecture for increased stress resilience [version 1; peer review: 2 approved, 1 approved with reservations]

Plant architecture develops post-embryonically and emerges from a dialogue between the developmental signals and environmental cues. Length and branching of the vegetative and reproductive tissues were the focus of improvement of plant performance from the early days of plant breeding. Current breeding priorities are changing, as we need to prioritize plant productivity under increasingly challenging environmental conditions. While it has been widely recognized that plant architecture changes in response to the environment, its contribution to plant productivity in the changing climate remains to be fully explored. This review will summarize prior discoveries of genetic control of plant architecture traits and their effect on plant performance under environmental stress. We review new tools in phenotyping that will guide future discoveries of genes contributing to plant architecture, its plasticity, and its contributions to stress resilience. Subsequently, we provide a perspective into how integrating the study of new species, modern phenotyping techniques, and modeling can lead to discovering new genetic targets underlying the plasticity of plant architecture and stress resilience. Altogether, this review provides a new perspective on the plasticity of plant architecture and how it can be harnessed for increased performance under environmental stress

Phosphate-dependent root system architecture responses to salt stress

Nutrient availability and salinity of the soil affect growth and development of plant roots. Here, we describe how phosphate availability affects root system architecture (RSA) of Arabidopsis and how phosphate levels modulate responses of the root to salt stress. Phosphate (Pi) starvation reduced main root length and increased the number of lateral roots of Arabidopsis Col-0 seedlings. In combination with salt, low Pi dampened the inhibiting effect of mild salt stress (75mM) on all measured RSA components. At higher NaCl concentrations, the Pi deprivation response prevailed over the salt stress only for lateral root elongation. The Pi deprivation response of lateral roots appeared to be oppositely affected by abscisic acid (ABA) signaling compared to the salt stress response. Natural variation in the response to the combination treatment of salt and Pi starvation within 330 Arabidopsis accessions could be grouped into four response patterns. When exposed to double stress, in general lateral roots prioritized responses to salt, while the effect on main root traits was additive. Interestingly, these patterns were not identical for all accessions studied and multiple strategies to integrate the signals from Pi deprivation and salinity were identified. By Genome Wide Association Mapping (GWAS) 13 genomic loci were identified as putative factors integrating responses to salt stress and Pi starvation. From our experiments, we conclude that Pi starvation interferes with salt responses mainly at the level of lateral roots and that large natural variation exists in the available genetic repertoire of accessions to handle the combination of stresses

Towards increased shading potential: a combined phenotypic and genetic analysis of rice shoot architecture

Rice feeds more than half of the world’s human population. In modern rice farming, a major constraint for productivity is weed proliferation and the ecological impact of herbicide application. Increased weed competitiveness of commercial rice varieties requires enhanced shade casting to limit growth of shade-sensitive weeds and the need for herbicide. We aimed to identify traits that enhance rice shading capacity based on the canopy architecture and the underlying genetic components. We performed a phenotypic screen of a rice diversity panel comprised of 344 varieties, examining 13 canopy architecture traits linked with shading capacity in 4-week-old plants. The analysis revealed a vast range of phenotypic variation across the diversity panel. We used trait correlation and clustering to identify core traits that define shading capacity to be shoot area, number of leaves, culm and solidity (the compactness of the shoot). To simplify the complex canopy architecture, these traits were combined into a Shading Rank metric that is indicative of a plant’s ability to cast shade. Genome wide association study (GWAS) revealed genetic loci underlying canopy architecture traits, out of which five loci were substantially contributing to shading potential. Subsequent haplotype analysis further explored allelic variation and identified seven haplotypes associated with increased shading. Identification of traits contributing to shading capacity and underlying allelic variation presented in this study will serve future genomic assisted breeding programmes. The investigated diversity panel, including widely grown varieties, shows that there is big potential and genetic resources for improvement of elite breeding lines. Implementing increased shading in rice breeding will make its farming less dependent on herbicides and contribute towards more environmentally sustainable agriculture. One sentence summary Through screening a rice diversity panel for variation in shoot architecture, we identified traits corresponding to plant shading potential and their genetic constituents

NAPPN 2024 Julkowska talk

Presentation by Magdalena Julkowska (Assistant Prof at BTI) delivered during NAPPN Meeting 2024 in West Lafayette, IN, USA on Feb 14th 2023</p

Lecture Slides Zhengzhou Summer School 2017

The series of lectures aimed at Bachelor Students or non-plant students from Zhengzhou University, Henan Province, People's Republic of China. The majority of the slides are designed by myself (Magdalena Julkowska) using whatever information I could find (trying to acknowledge the sources as much as possible, but not always succeeded in this).<div><br></div><div>The slides are in English and the Salt Stress Physiology part is based on the lectures given by Prof. Mark Tester at King Abdullah University of Science in Technology, Thuwal, The Kingdom of Saudi Arabia. </div

Salt_NV_RootApp

<div>The code for the Salt NV Root App, enabling interactive exploration of the Root System Architecture phenotypes collected for 347 accessions of Arabidopsis grown under control and two salt stress conditions.</div><div><br></div><div>The app includes:</div><div>- Comparison of RSA phenotypes of individual accessions in all conditions studied</div><div>- Comparison of RSA phenotypes between 8 accessions </div><div>- Correlation analysis </div><div>- Clustering of the accessions based on the chosen RSA phenotypes</div><div><br></div>The app was published along with the Plant Cell paper: <div>http://www.plantcell.org/content/early/2017/11/07/tpc.16.00680<br></div

mmjulkowska/MVApp: Version_beta_extreme

This version is still under construction with a lot of glitches, but just checking the Zenodo doi creatio

The Use of High-Throughput Phenotyping for Assessment of Heat Stress-Induced Changes in Arabidopsis

The worldwide rise in heatwave frequency poses a threat to plant survival and productivity. Determining the new marker phenotypes that show reproducible response to heat stress and contribute to heat stress tolerance is becoming a priority. In this study, we describe a protocol focusing on the daily changes in plant morphology and photosynthetic performance after exposure to heat stress using an automated noninvasive phenotyping system. Heat stress exposure resulted in an acute reduction of the quantum yield of photosystem II and increased leaf angle. In longer term, the exposure to heat also affected plant growth and morphology. By tracking the recovery period of the WT and mutants impaired in thermotolerance (hsp101), we observed that the difference in maximum quantum yield, quenching, rosette size, and morphology. By examining the correlation across the traits throughout time, we observed that early changes in photochemical quenching corresponded with the rosette size at later stages, which suggests the contribution of quenching to overall heat tolerance. We also determined that 6 h of heat stress provides the most informative insight in plant’s responses to heat, as it shows a clear separation between treated and nontreated plants as well as the WT and hsp101. Our work streamlines future discoveries by providing an experimental protocol, data analysis pipeline, and new phenotypes that could be used as targets in thermotolerance screenings

Genetic Loci Associated with Early Salt Stress Responses of Roots

Salinity is a devastating abiotic stress accounting for major crop losses yearly. Plant roots can strikingly grow away from high-salt patches. This response is termed halotropism and occurs through auxin redistribution in roots in response to a salt gradient. Here, a natural variation screen for the early and NaCl-specific halotropic response of 333 Arabidopsis accessions revealed quantitative differences in the first 24 h. These data were successfully used to identify genetic components associated with the response through Genome-Wide Association Study (GWAS). Follow-up characterization of knockout mutants in Col-0 background confirmed the role of transcription factor WRKY25, cation-proton exchanger CHX13, and a gene of unknown function DOB1 (Double Bending 1) in halotropism. In chx13 and dob1 mutants, ion accumulation and shoot biomass under salt stress were also affected. Thus, our GWAS has identified genetic components contributing to main root halotropism that provide insight into the genetic architecture underlying plant salt responses.</p