A model for the relationship between plant biomass and photosynthetic rate based on nutrient effects

A metabolic perspective on polyploid invasion and the emergence of life histories: Insights from a mechanistic model

PREMISE

Whole-genome duplication (WGD, polyploidization) has been identified as a driver of genetic and phenotypic novelty, having pervasive consequences for the evolution of lineages. While polyploids are widespread, especially among plants, the long-term establishment of polyploids is exceedingly rare. Genome doubling commonly results in increased cell sizes and metabolic expenses, which may be sufficient to modulate polyploid establishment in environments where their diploid ancestors thrive.

METHODS

We developed a mechanistic simulation model of photosynthetic individuals to test whether changes in size and metabolic efficiency allow autopolyploids to coexist with, or even invade, ancestral diploid populations. Central to the model is metabolic efficiency, which determines how energy obtained from size-dependent photosynthetic production is allocated to basal metabolism as opposed to somatic and reproductive growth. We expected neopolyploids to establish successfully if they have equal or higher metabolic efficiency as diploids or to adapt their life history to offset metabolic inefficiency.

RESULTS

Polyploid invasion was observed across a wide range of metabolic efficiency differences between polyploids and diploids. Polyploids became established in diploid populations even when they had a lower metabolic efficiency, which was facilitated by recurrent formation. Competition for nutrients is a major driver of population dynamics in this model. Perenniality did not qualitatively affect the relative metabolic efficiency from which tetraploids tended to establish.

CONCLUSIONS

Feedback between size-dependent metabolism and energy allocation generated size and age differences between plants with different ploidies. We demonstrated that even small changes in metabolic efficiency are sufficient for the establishment of polyploids.

Density affects plant size in the Gobi Desert

Plant size is a crucial functional trait with substantial implications in agronomy and forestry. Understanding the factors influencing plant size is essential for ecosystem management and restoration efforts. Various environmental factors and plant density play significant roles in plant size. However, how plant size responds to mean annual precipitation (MAP), mean annual temperature (MAT), and density in the arid areas remains incomplete. To address this knowledge gap, we conducted comprehensive vegetation surveys in the Gobi Desert in northwestern China with a MAP below 250 mm. We also collected climate data to disentangle the respective influences of climate and density on the community-weighted plant height, crown length, and crown width. Our observations revealed that the community-weighted mean plant height, crown length, and width demonstrated a positive association with MAT but negative relationships with both MAP and density. These patterns can be attributed to the predominance of shrubs over herbs in arid regions, as shrubs tend to be larger in size. The proportion of shrubs increases with MAT, while it decreases with MAP and density, resulting in higher plant height and larger crown dimensions. Although both MAP and MAT affect plant size in the Gobi Desert, our findings highlight the stronger role of plant density in regulating plant size, indicating that the surrounding plant community and competition among individuals are crucial drivers of plant size patterns. Our findings provide valuable guidance for nature-based solutions for vegetation restoration and ecosystem management, highlighting the importance of considering plant density as a key factor when designing and implementing restoration strategies in arid areas.

Biostimulatory Effects of Chlorella fusca CHK0059 on Plant Growth and Fruit Quality of Strawberry

Green algae have been receiving widespread attention for their use as biofertilizers for agricultural production, but more studies are required to increase the efficiency of their use. This study aimed to investigate the effects of different levels of Chlorella fusca CHK0059 application on strawberry plant growth and fruit quality. A total of 800 strawberry seedlings were planted in a greenhouse and were grown for seven months under different Chlorella application rates: 0 (control), 0.1, 0.2, and 0.4% of the optimal cell density (OCD; 1.0 × 107 cells mL-1). The Chlorella application was conducted weekly via an irrigation system, and the characteristics of fruit samples were monitored monthly over a period of five months. The growth (e.g., phenotype, dry weight, and nutrition) and physiological (e.g., Fv/Fm and chlorophylls) parameters of strawberry plants appeared to be enhanced by Chlorella application over time, an enhancement which became greater as the application rate increased. Likewise, the hardness and P content of strawberry fruits had a similar trend. Meanwhile, 0.2% OCD treatment induced the highest values of soluble solid content (9.3-12 °Brix) and sucrose content (2.06-2.97 g 100 g-1) in the fruits as well as fruit flavor quality indices (e.g., sugars:acids ratio and sweetness index) during the monitoring, whilst control treatment represented the lowest values. In addition, the highest anthocyanin content in fruits was observed in 0.4% OCD treatment, which induced the lowest incidence of grey mold disease (Botrytis cinerea) on postharvest fruits for 45 days. Moreover, a high correlation between plants' nutrients and photosynthetic variables and fruits' sucrose and anthocyanin contents was identified through the results of principal component analysis. Overall, C. fusca CHK0059 application was found to promote the overall growth and performance of strawberry plants, contributing to the improvement of strawberry quality and yield, especially in 0.2% OCD treatment.