Journal of Plant Research最新文献

In mutualistic symbiosis between plants and bacteria, the abundance and composition of symbiotic bacterial groups in the soil microbiota can be important for plant growth. Here, we focused on the nitrogen-fixing mutualism between Lotus japonicus and nodule bacteria to investigate whether and how much the abundance of symbiotic rhizobia in the soil microbiota of natural environments contributes to variations in host plant growth. An inoculation experiment of soil microbiota revealed extensive variations in plant growth phenotypes, even between microhabitats. We found that the local presence of L. japonicus and the relative abundance of Mesorhizobium bacteria showed positive correlations with plant growth supported by both 16S amplicon sequencing and shotgun metagenome analyses. Among bacteria investigated, the abundance of Mesorhizobium was most strongly associated with plant growth phenotypes, supporting its role as the primary symbiotic rhizobia in natural environments. Given the specificity and the selectivity of plants for favorable rhizobia, legume-rhizobia interactions could trigger a positive plant-soil feedback that enriches favorable rhizobia into the soil surrounding legume plant habitats.

Climate change imposes negative impacts on forest ecosystems through both abiotic stressors, such as drought, and biotic stressors, such as insect-induced defoliation. Chinese pine (Pinus tabulaeformis), a primary afforestation species in the northwest region of China, has recently faced increasing threats from drought and defoliation, leading to widespread mortality. This study investigates the combined effects of drought and defoliation on the growth and non-structural carbohydrate (NSC) dynamics of Chinese pine seedlings. A greenhouse-based manipulative experiment lasting 80 days was conducted, incorporating three watering treatments (100% field water-holding capacity, 30-40% field water-holding capacity, and no watering) and two defoliation treatments (defoliated and non-defoliated). Under moderate drought, seedlings exhibited increased concentrations of soluble sugars and starch in leaves and stems, demonstrating an active resistance to drought stress. However, under severe drought, NSC concentrations significantly decreased in all organs. Defoliation exacerbated the negative effects of drought, particularly impairing the NSC reserves in roots, thereby weakening the resilience of seedlings. The combination between drought and defoliation significantly altered the allocation patterns of soluble sugars and starch among roots, stems, and leaves in Chinese pine, highlighting the critical role of NSC in plant responses to environmental stressors. This study emphasizes the need to consider both drought and defoliation challenges simultaneously in ecological restoration practices to ensure the resilience of forest ecosystems.

Plastid ribosomal proteins (PRPs) are core components of the plastid translational machinery, playing indispensable roles in chloroplast biogenesis and plant growth. While the functions of some PRPs in rice have been characterized, the biological role of the plastid 50 S ribosomal protein L5 (PRPL5) remains unclear. Here, we characterize the function of Albino Lethal Seedling 2 (ALS2), encoding the PRPL5, in early chloroplast development. CRISPR/Cas9-mediated knockout of ALS2 resulted in seedling-lethal albino phenotypes, significantly reduced chlorophyll concentration, and disrupted chloroplast ultrastructure. ALS2 is highly expressed in rice leaves and its protein is localized in rice chloroplasts. Further analysis of gene expression revealed that nuclear and plastid genes participating in chloroplast development showed notable alterations in their expression in the als2 mutants. Notably, als2 mutants accumulated reactive oxygen species (ROS), particularly superoxide anions, which was accompanied by enhanced expression of ROS-scavenging genes and chlorophyll degradation genes. These findings demonstrate that ALS2 is essential for early chloroplast development in rice.

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.