More Like this

1. Living with high potassium: Balance between nutrient acquisition and K-induced salt stress signaling

   https://doi.org/10.1093/plphys/kiac564  

   Pantha, Pramod; Oh, Dong-Ha; Longstreth, David; Dassanayake, Maheshi (December 2022, Plant Physiology)

   Abstract High potassium (K) in the growth medium induces salinity stress in plants. However, the molecular mechanisms underlying plant responses to K-induced salt stress are virtually unknown. We examined Arabidopsis (Arabidopsis thaliana) and its extremophyte relative Schrenkiella parvula using a comparative multiomics approach to identify cellular processes affected by excess K and understand which deterministic regulatory pathways are active to avoid tissue damages while sustaining growth. Arabidopsis showed limited capacity to curb excess K accumulation and prevent nutrient depletion, contrasting to S. parvula which could limit excess K accumulation without restricting nutrient uptake. A targeted transcriptomic response in S. parvula promoted nitrogen uptake along with other key nutrients followed by uninterrupted N assimilation into primary metabolites during excess K-stress. This resulted in larger antioxidant and osmolyte pools and corresponded with sustained growth in S. parvula. Antithetically, Arabidopsis showed increased reactive oxygen species levels, reduced photosynthesis, and transcriptional responses indicative of a poor balance between stress signaling, subsequently leading to growth limitations. Our results indicate that the ability to regulate independent nutrient uptake and a coordinated transcriptomic response to avoid nonspecific stress signaling are two main deterministic steps toward building stress resilience to excess K+-induced salt stress. 

   more » « less
2. Positive selection and heat‐response transcriptomes reveal adaptive features of the Brassicaceae desert model, Anastatica hierochuntica

   https://doi.org/10.1111/nph.18411  

   Eshel, Gil; Duppen, Nick; Wang, Guannan; Oh, Dong‐Ha; Kazachkova, Yana; Herzyk, Pawel; Amtmann, Anna; Gordon, Michal; Chalifa‐Caspi, Vered; Oscar, Michelle Arland; et al (August 2022, New Phytologist)

   Summary Plant adaptation to a desert environment and its endemic heat stress is poorly understood at the molecular level. The naturally heat‐tolerant Brassicaceae speciesAnastatica hierochunticais an ideal extremophyte model to identify genetic adaptations that have evolved to allow plants to tolerate heat stress and thrive in deserts.We generated anA. hierochunticareference transcriptome and identified extremophyte adaptations by comparingArabidopsis thalianaandA. hierochunticatranscriptome responses to heat, and detecting positively selected genes inA. hierochuntica.The two species exhibit similar transcriptome adjustment in response to heat and theA. hierochunticatranscriptome does not exist in a constitutive heat ‘stress‐ready’ state. Furthermore, theA. hierochunticaglobal transcriptome as well as heat‐responsive orthologs, display a lower basal and higher heat‐induced expression than inA. thaliana. Genes positively selected in multiple extremophytes are associated with stomatal opening, nutrient acquisition, and UV‐B induced DNA repair while those unique toA. hierochunticaare consistent with its photoperiod‐insensitive, early‐flowering phenotype.We suggest that evolution of a flexible transcriptome confers the ability to quickly react to extreme diurnal temperature fluctuations characteristic of a desert environment while positive selection of genes involved in stress tolerance and early flowering could facilitate an opportunistic desert lifestyle. 

   more » « less
3. Necrotic upper tips1 mimics heat and drought stress and encodes a protoxylem-specific transcription factor in maize

   https://doi.org/10.1073/pnas.2005014117  

   Dong, Zhaobin; Xu, Zhennan; Xu, Ling; Galli, Mary; Gallavotti, Andrea; Dooner, Hugo K.; Chuck, George (August 2020, Proceedings of the National Academy of Sciences)

   null (Ed.)

   Maintaining sufficient water transport during flowering is essential for proper organ growth, fertilization, and yield. Water deficits that coincide with flowering result in leaf wilting, necrosis, tassel browning, and sterility, a stress condition known as “tassel blasting.” We identified a mutant, necrotic upper tips1 ( nut1 ), that mimics tassel blasting and drought stress and reveals the genetic mechanisms underlying these processes. The nut1 phenotype is evident only after the floral transition, and the mutants have difficulty moving water as shown by dye uptake and movement assays. These defects are correlated with reduced protoxylem vessel thickness that indirectly affects metaxylem cell wall integrity and function in the mutant. nut1 is caused by an Ac transposon insertion into the coding region of a unique NAC transcription factor within the VND clade of Arabidopsis . NUT1 localizes to the developing protoxylem of root, stem, and leaf sheath, but not metaxylem, and its expression is induced by flowering. NUT1 downstream target genes function in cell wall biosynthesis, apoptosis, and maintenance of xylem cell wall thickness and strength. These results show that maintaining protoxylem vessel integrity during periods of high water movement requires the expression of specialized, dynamically regulated transcription factors within the vasculature. 

   more » « less
4. Differences in drought avoidance rather than differences in the fast versus slow growth spectrum explain distributions of two Asclepias species

   https://doi.org/10.1111/ppl.70034  

   Matzner, Steven_L; Konz, Emily_R; Marts, Samantha_A; Eversman, Haley_M; Kasuske, Kyla_M; Atkins, Trinity_L; Acharya, Sneha; Matuck, Lara_C; Derynck, Lillian_M; Kreutzmann, Sydney; et al (December 2024, Physiologia Plantarum)

   Abstract Understanding factors that determine a species' geographical range is crucial for predicting climate‐induced range shifts. Two milkweed species,Asclepias syriacaandAsclepias speciosa, have overlapping ranges along a moisture gradient in North America and are primary food sources for endangered monarch caterpillars. With decreasing moisture, long‐lived species often exhibit slower growth and greater drought tolerance, while many annual species exhibit faster growth strategies. Using this fast‐slow framework, we assessed whether traits of these two sister species differ along a fast‐slow growth continuum and could explain their distributions. We measured leaf and root functional traits in common gardens and greenhouse experiments. In key measures indicative of drought tolerance (e.g., growth, transpiration, and water potentials), the species were nearly identical. Contrary to expectations,A. speciosadid not exhibit greater drought tolerance, raising the question of how it survives in the more arid west. A reciprocal transplant study showed selection againstA. syriacain the western garden and thatA. speciosawas better able to avoid seedling mortality. Focusing on seedling establishment, we found thatA. speciosaexhibited faster deep‐root development and a narrow leaf phenotype associated with slower wilting and delayed drought‐induced mortality. Rather than differences on the fast‐slow growth spectrum, our results indicate thatA. speciosaavoids drought through faster deep‐root growth and a slower wilting phenotype. Our study suggests thatA. syriaca'srange is limited by its drought tolerance, while A. speciosaemploys a number of drought avoidance strategies to survive in more arid environments. 

   more » « less
5. Earlier snow melt and reduced summer precipitation alter floral traits important to pollination

   https://doi.org/10.1111/gcb.15908  

   Powers, John_M; Briggs, Heather_M; Dickson, Rachel_G; Li, Xinyu; Campbell, Diane_R (October 2021, Global Change Biology)

   Abstract Climate change can cause changes in expression of organismal traits that influence fitness. In flowering plants, floral traits can respond to drought, and that phenotypic plasticity has the potential to affect pollination and plant reproductive success. Global climate change is leading to earlier snow melt in snow‐dominated ecosystems as well as affecting precipitation during the growing season, but the effects of snow melt timing on floral morphology and rewards remain unknown. We conducted crossed manipulations of spring snow melt timing (early vs. control) and summer monsoon precipitation (addition, control, and reduction) that mimicked recent natural variation, and examined plastic responses in floral traits ofIpomopsis aggregataover 3 years in the Rocky Mountains. We tested whether increased summer precipitation compensated for earlier snow melt, and if plasticity was associated with changes in soil moisture and/or leaf gas exchange. Lower summer precipitation decreased corolla length, style length, corolla width, sepal width, and nectar production, and increased nectar concentration. Earlier snow melt (taking into account natural and experimental variation) had the same effects on those traits and decreased inflorescence height. The effect of reduced summer precipitation was stronger in earlier snow melt years for corolla length and sepal width. Trait reductions were explained by drier soil during the flowering period, but this effect was only partially explained by how drier soils affected plant water stress, as measured by leaf gas exchange. We predicted the effects of plastic trait changes on pollinator visitation rates, pollination success, and seed production using prior studies onI. aggregata. The largest predicted effect of drier soil on relative fitness components via plasticity was a decrease in male fitness caused by reduced pollinator rewards (nectar production). Early snow melt and reduced precipitation are strong drivers of phenotypic plasticity, and both should be considered when predicting effects of climate change on plant traits in snow‐dominated ecosystems. 

   more » « less