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1. Divergent gametic thermal performance and floral warming across an elevation gradient

   https://doi.org/10.1093/evolut/qpad237  

   Heiling, Jacob M; Koski, Matthew H (January 2024, Evolution)

   Friedman, Jannice; Connallon, Tim (Ed.)

   Abstract Thermal environments vary widely across species ranges, establishing the potential for local adaptation of thermal performance optima and tolerance. In the absence of local adaptation, selection should favor mechanisms to meet thermal optima. Floral temperature is a major determinant of reproductive success in angiosperms, yet whether gametic thermal performance shows signatures of local adaptation across temperature gradients, and how variation in gametic thermal performance influences floral evolution, is unknown. We characterized flowering season temperatures for the forb, Argentina anserina, at extremes of a 1000 m elevation gradient and generated thermal performance curves for pollen and ovule performance in populations at each extreme. Thermal optima fell between mean and maximum intrafloral temperatures. However, cooler high-elevation populations had ~4 °C greater pollen thermal optima than warmer low-elevation populations, while tolerance breadths did not differ. We then tested whether plants at elevational extremes differentially warmed the floral microenvironment. High-elevation flowers warmed significantly more than low, bringing intrafloral temperatures nearer the pollen optima. A manipulative experiment demonstrated that stronger warming in high elevation was conferred by floral tissues. Elevational divergence in floral warming may be driven, in part, by selection on flowers to meet different thermal demands of the gametophytes. 

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2. Cold tolerance response mechanisms revealed through comparative analysis of gene and protein expression in multiple rice genotypes

   de Freitas GM, Thomas J (June 2019, PloS one)

   Due to its tropical origin and adaptation, rice is significantly impacted by cold stress, and consequently sustains large losses in growth and productivity. Currently, rice is the second most consumed cereal in the world and production losses caused by extreme temperature events in the context of "major climatic changes" can have major impacts on the world economy. We report here an analysis of rice genotypes in response to low-temperature stress, studied through physiological gas-exchange parameters, biochemical changes in photosynthetic pigments and antioxidants, and at the level of gene and protein expression, towards an understanding and identification of multiple low-temperature tolerance mechanisms. The first effects of cold stress were observed on photosynthesis among all genotypes. However, the tropical japonica genotypes Secano do Brazil and Cypress had a greater reduction in gas exchange parameters like photosynthesis and water use efficiency in comparison to the temperate japonica Nipponbare and M202 genotypes. The analysis of biochemical profiles showed that despite the impacts of low temperature on tolerant plants, they quickly adjusted to maintain their cellular homeostasis by an accumulation of antioxidants and osmolytes like phenolic compounds and proline. The cold tolerant and sensitive genotypes showed a clear difference in gene expression at the transcript level for OsGH3-2, OsSRO1a, OsZFP245, and OsTPP1, as well as for expression at the protein level for LRR-RLKs, bHLH, GLYI, and LTP1 proteins. This study exemplifies the cold tolerant features of the temperate japonica Nipponbare and M202 genotypes, as observed through the analysis of physiological and biochemical responses and the associated changes in gene and protein expression patterns. The genes and proteins showing differential expression response are notable candidates towards understanding the biological pathways affected in rice and for engineering cold tolerance, to generate cultivars capable of maintaining growth, development, and reproduction under cold stress. We also propose that the mechanisms of action of the genes analyzed are associated with the tolerance response. 

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3. Role of heterotrimeric G-proteins in improving abiotic stress tolerance of crop plants

   Parinita Majumdar, P; Torres Rodríguez, MD; Pandey, S (January 2022, Journal of plant growth regulation)

   Sopory, SK (Ed.)

   As sessile organisms, plants are constantly exposed to a variety of environmental stresses that have detrimental effects on their growth and development, leading to major crop yield losses worldwide. To cope with adverse conditions plants have developed several adaptive mechanisms. A thorough understanding these mechanisms is critical to generate plants for the future. The heterotrimeric G-protein complex, composed of Gα, Gβ, and Gγ subunits, participates in regulation of multiple cellular signaling pathways and have multifaceted roles in regulating stress responses of plants. The complex has two functional entities, the GTP-bound Gα subunit and the Gβγ dimer, both of which by interacting with additional proteins can activate various signaling networks. The involvement of G-proteins has been shown in plants’ response to drought, salinity, extreme temperatures, heavy metal, ozone, and UV-B radiation. Due to their versatility and the number of processes modulated by them, G-proteins have emerged as key targets for generating stress tolerant crops. In this review, we provide an overview of the current knowledge of the roles of G proteins in abiotic stress tolerance, with examples from model plant Arabidopsis thaliana, where these processes are most widely studied and from additional agriculturally relevant crops, where their potential is realized for human usage. 

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4. Floral thermal biology in relation to pollen thermal performance in an early spring flowering plant

   https://doi.org/10.1111/plb.13660  

   Sherer, T N; Heiling, J M; Koski, M H (June 2024, Plant Biology)

   Abstract The floral microenvironment impacts gametophyte viability and plant–pollinator interactions. Plants employ mechanisms to modify floral temperature, including thermogenesis, absorption of solar radiation, and evaporative cooling. Whether floral thermoregulation impacts reproductive fitness, and how floral morphological variation mediates thermoregulatory capacity are poorly understood.We measured temperature of the floral microenvironment in the field and tested for thermogenesis in the lab in early spring floweringHexastylis arifolia(Aristolochiaceae). We evaluated whether thermoregulatory capacity was associated with floral morphological variation. Finally, we experimentally determined the thermal optimum and tolerance of pollen to assess whether thermoregulation may ameliorate thermal stress to pollen.Pollen germination was optimal near 21 °C, with a 50% tolerance breadth of ~18 °C. In laboratory conditions, flowers exhibited thermogenesis of 1.5–4.8 °C for short intervals within a conserved timeframe (08:00–09:00 h). In the field, temperature inside the floral tube often deviated from ambient – floral interiors were up to 4 °C above ambient when it was cold, but some fell nearly 10 °C below ambient during peak heat. Flowers with smaller openings were cooler and more thermally stable than those with larger openings during peak heat. Thermoregulation maintained a floral microenvironment within the thermal tolerance breadth of pollen.Results suggest thatH. arifoliaflowers have a stronger capacity to cool than to warm, and that narrower floral openings create a distinct floral microenvironment, enhancing floral cooling effects. While deviation of floral temperature from ambient conditions maintains a suitable environment for pollen and suggests an adaptive role of thermoregulation, we discuss adaptive and nonadaptive mechanisms underlying floral warming and cooling. 

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5. The promise of resurrection plants in enhancing crop tolerance to water scarcity

   https://doi.org/10.1098/rstb.2024.0231  

   Shumayla; Alejo-Jacuinde, Gerardo; Silva-Villatoro, Pablo; Nwoko, Chidinma Lois; Oliver, Melvin J; Herrera-Estrella, Luis (May 2025, Philosophical Transactions of the Royal Society B: Biological Sciences)

   Climate change affects the agricultural sector by modifying precipitation patterns, increasing extreme weather events, and geographically shifting agriculturally viable areas. These climate alterations substantially impact plant resilience to abiotic stress and, consequently, agricultural productivity. A better understanding of plant adaptations to tolerate extreme environmental conditions could pave the way for future advances in agricultural sustainability. One such adaptation is vegetative desiccation tolerance (VDT), which enables some species, known as ‘resurrection plants’, to undergo almost complete drying without losing viability. The current review discusses how incorporating different molecular and biochemical mechanisms underlying VDT into crops might expand the time during which crops can continue growing under limiting water conditions and perhaps broaden the range of survivable negative water potentials that a crop can endure under drought stress. Such possibilities could alleviate the detrimental consequences of low water availability to crops. Understanding how plants survive extreme dehydration has the potential to enlighten new strategies to improve the climate resiliency of crops, thereby positively impacting worldwide food security and sustainability. 

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