Journal of Plant Research最新文献

Medakamo hakoo is an ultrasmall green alga with a simplified cellular structure, offering potential as a new model organism. To explore the genetic basis of cell morphology and its physiological implications, we applied carbon-ion beam irradiation to induce mutations in M. hakoo and successfully isolated two mutants: LRG (Large) and TTR (Tetra). LRG exhibited significantly enlarged cell size and increased chlorophyll content, but lower photosynthetic efficiency compared to the wild-type. Proteomic analysis of LRG revealed upregulation of photosynthesis-related proteins, stress response proteins, and ribosomal proteins, suggesting a link between increased cell size and disrupted photosynthetic homeostasis. TTR showed a higher proportion of dividing cells throughout the light-dark cycle and exhibited cell aggregation. Proteomic profiling revealed increased abundance of dynein and cell wall-modifying enzymes such as expansin and mannosidases, indicating that TTR may undergo cell cycle delay or dysregulation of cytoplasmic and cell wall dynamics. TTR also displayed decreased levels of photosynthetic proteins and reduced photosynthetic activity. Both mutants demonstrated slower growth compared to the wild-type. These findings highlight the close relationship between cell size and cell cycle/cell wall dynamics with photosynthetic activity, providing new insights into the cellular regulatory mechanisms of photosynthetic microalgae. Our study also demonstrates the utility of heavy-ion mutagenesis in dissecting microalgal physiology in species for which genetic transformation systems have not yet been developed.

Kalanchoe species, originally introduced worldwide as ornamentals, are now reported to be globally spreading in many regions, including China. It is hypothesized that the morphological plasticity and asexual plantlet production of these species contribute to their rapid invasive spread. To address this hypothesis, an experiment was conducted using four Kalanchoe species: Kalanchoe delagoensis Eckl. & Zeyh., Kalanchoe × houghtonii D. B. Ward, Kalanchoe laetivirens Desc. and Kalanchoe daigremontiana Raym.-Hamet & H. Perrier. The reproductive and vegetative traits of these four species were evaluated under contrasting light and water conditions. The plants subjected to high light tended to prioritize plantlet production, accompanied by a reduction in vegetative growth. Two distinct reproductive strategies were observed. K. delagoensis and K. × houghtonii significantly increased plantlet production under high light conditions. In contrast, K. daigremontiana and K. laetivirens enhanced the fresh weight of individual plantlets without altering the total number produced. These results demonstrate the high plasticity of vegetative and reproductive growth in response to light and water availability. The increased production of plantlets may contribute to the invasive spread of Kalanchoe species in open fields.

Deceptive pollination exploits pollinator perceptual biases while offering no reward. Arisaema (Araceae) employs an extreme form of this strategy, in which fungus gnats are lured into a slippery floral tube that often proves fatal. However, the key factors governing attraction and capture remain poorly understood, partly due to the typically low frequency of floral visitation. Preliminary observations revealed that Arisaema serratum exhibits a relatively high visitation rate of fungus gnats. We therefore conducted direct behavioral observations of pollinators associated with A. serratum in a controlled field plot, combining video monitoring with morphometric analyses. Over two years, we recorded 2459 visits by male Cordyla sixi (Mycetophilidae) during 64 hours of observation, confirming a highly specialized interaction. Visit frequency declined only after floral senescence, with no progressive decrease observed within daily sessions, indicating negligible learning-based avoidance. Morphometric analyses suggested a positive correlation between thicker appendices and increased visitation, as well as between larger spathes and increased visitation, but a negative correlation between higher inflorescence placement and visitation, likely reflecting the low flight path of fungus gnats. Behavioral observations revealed frequent genital displays, wing-fanning, and exploratory walking on the appendix. Simultaneous visits by multiple males prolonged residence time and facilitated the arrival of additional individuals. Together, these findings support a scenario in which floral scent mimics sexual or aggregation pheromones, attracting dense male assemblies and enhancing pollination success. This study provides the first detailed ethogram of fungus gnat behavior associated with Arisaema, thereby offering novel insights into the mechanistic basis of this highly exploitative pollination system.

Reproductive interference is a negative interspecific interaction that can drive mutually exclusive distributions of closely related species. While recent research indicates that reproductive interference in plants frequently occurs during pollen-pistil interactions, comprehensive descriptions of these interactions are scarce. Understanding the mechanisms underlying reproductive interference requires studies integrating empirical observations with interaction analyses. This study investigates pollen-pistil interactions between three Veronica species recently observed to exhibit asymmetric reproductive interference.Our experiments revealed similar pollen tube behavior in V. polita var. lilacina and V. cymbalaria pistils, irrespective of whether they were pollinated with conspecific or V. persica pollen. Conversely, in V. persica pistils, the number of pollen tubes significantly decreased following heterospecific pollination compared to conspecific pollination. Furthermore, half of the pollen grains on V. persica stigmas, presumably heterospecific pollen grains, occasionally appeared non-luminous under the fluorescence microscope after mixed pollination. Conspecific pollen tubes appeared to grow faster within V. persica pistils; however, statistical analysis did not support this trend.These results suggest that V. polita var. lilacina and V. cymbalaria pistils exhibit limited discrimination against V. persica pollen, resulting in ovule discounting by the heterospecific pollen. This mechanism explains the empirical observation that these species experience reduced seed set after mixed pollination, even when conspecific pollen is applied first. In contrast, V. persica pistils demonstrate a degree of discrimination between conspecific and heterospecific pollen, particularly when conspecific pollen arrives on the stigma prior to heterospecific pollen. This selectivity accounts for the empirical findings that V. persica exhibits reduced seed set only when surrounded by V. polita var lilacina or after mixed pollination with V. cymbalaria pollen preceding conspecific pollen.

Cassava (Manihot esculenta Crantz) is a prioritized crop for food security for nearly one billion people worldwide. We examined the genetic structure and diversity in a panel of 176 cassava cultivars from diverse biogeographic regions of Colombia using a total of 57,410 SNP markers obtained by Genotyping-by-Sequencing (GBS). A moderately high total diversity, heterozygotes deficit and inbreeding were found. Furthermore, we find three distinct genetic clusters (GC1, GC2 and GC3) with clear geographic correspondence to Amazonian, Andean, and Caribbean Colombian regions, a substantial phenotypic correlation with root bitterness and a greater differentiation between clusters than typically found in global scale studies. Each genetic cluster exhibits distinctive selection signatures reflecting region specific adaptations. GPI-anchor biosynthesis and chitin catabolism in Amazonian bitter cassava (defense against pathogens), oxidative stress response in Andean cassava (adaptation to highland conditions) and trehalose biosynthesis, cyano-amino acid metabolism and tuberization accumulation in Caribbean sweet cassava (drought tolerance, altered cyanogen processing and tuberization characteristics). These signatures align with phenotypic differentiation between bitter and sweet cultivars. These analyses highlight Colombia as a unique diversification core where environmental challenges and cultural practices have structured cassava diversity, underscoring the importance of integrated conservation strategies that preserve both genetic resources and the traditional knowledge systems that sustain them.

The Stress Gradient Hypothesis (SGH) predicts that the net effects of competition and facilitation among plants are determined by the interactions with environmental stressors. Juniperus virginiana is a stress-tolerant species that is native to the eastern United States but expanding into novel habitats, which may interact with changes in plant density as invasion proceeds to shape the course of species establishment. We tested this hypothesis by examining three sites along a complex latitudinal gradient shaped by historical glaciation and varying in snowfall, temperature, precipitation, and soil nutrients. We examined the impact of intraspecific competition (zero, one, two, and four competitors) on J. virginiana sapling growth metrics (relative growth rate, total biomass, and nitrogen concentration), physiological traits (midday water potential, assimilation rate, transpiration rate, and stomatal conductance), and water status. We found that abiotic conditions impacted plants in a non-linear fashion along a complex stress gradient, with the highest performance at high and low latitude sites. Intraspecific competition had limited effects overall, though some evidence suggests that negative impacts would develop over time at the highest density. Our study testing the expectations of SGH using this stress-tolerant species demonstrates how the theory can be applied to inform invasion management plans by showing that (1) intraspecific competition alone is unlikely to impact J. virginiana performance except at high plant densities, (2) environmental complexity, including the combined effect of temperature, precipitation, soil nutrient content, and competition, is a more likely driver of productivity and establishment, however (3) warmer, drier sites with higher soil nitrogen are expected to support higher growth rates, making them more vulnerable to J. virginiana invasion.