Journal of Experimental Botany最新文献

The transcription factor StBEL11 is known as a negative regulator of tuberization in the Andean potato (Solanum tuberosum ssp. andigena). This study focuses on its role in the common potato ssp. tuberosum by analysing transgenic lines of cv. Kamýk with down-regulated StBEL11 expression. As expected, these lines showed enhanced tuber induction on nodal segments cultivated in vitro on high-sucrose medium. However, intact plants ex vitro exhibited significantly delayed tuberization and decreased yield, which surprisingly applied especially for lines with the most enhanced in vitro tuberization. Interestingly, reduced leaf StBEL11 expression was accompanied by decreased leaf expression of the positive tuberization regulator StBEL5, but not of SP6A tuberigen. The transgenics showed increased photosynthetic activity, which was not, however, associated with non-structural carbohydrate accumulation. Unexpectedly, StBEL11 down-regulation altered assimilate allocation in favour of roots over shoots and stolons before onset of tuberization and, in lines with the strongest phenotype, also during the early stage of tuberization, which probably explains their reduced tuber yields. The unexpected differences in tuber induction and yield between andigena and tuberosum lines with down-regulated StBEL11 indicate changes in the strength/hierarchy of individual components of the tuberization regulatory network and point to the impossibility of easy knowledge transfer from Andean to cultivated potato.

In order to fix the problem of low contrast and lost detail in micro-computed tomography (micro-CT) images of rice seedling stems that have been embedded in paraffin, we propose a method for improving the images which combines a diffusion model with a pre-enhancement network. First, the triple wavelet attention (TWA) module and the selective kernel feature fusion (SKFF) module are integrated to create the multi-scale residual block (MSRB), which is the main building block of the pre-enhancement network. The overall clarity of the images is improved by this integration, which also successfully broadens the receptive field. Then, the variational information bottleneck (VIB) block is included to further eliminate noise information from the denoising diffusion probabilistic model (DDPM) and enhance its noise prediction network. Finally, the enhanced DDPM model then uses the output characteristics of the pre-enhancement network as conditional inputs to produce CT images of rice seedling stems that have a better sense of hierarchy. According to experimental data, the suggested approach outperforms the comparison methods in terms of several objective assessment metrics. Furthermore, the computational efficiency of this approach is 7.65 times greater than that of the conventional DDPM, providing robust technical support for subsequent complex computer vision applications.

3',5'-cAMP is a ubiquitous signaling molecule across kingdoms. Although cAMP was identified early in plants, its significance remained underappreciated. Recent discoveries revealed that nuclear auxin receptors (TIR1/AFBs) possess intrinsic adenylyl cyclase (AC) activity. Crucially, the cAMP produced can participate in transcriptional regulation semi-independently of canonical receptor function, transforming our understanding of the regulatory roles of cAMP in plants. This review systematically synthesizes: (i) the molecular basis of cAMP homeostasis; (ii) identification and functions of downstream effectors; and (iii) the role of cAMP in plant development, stress responses, and hormone interactions. We further highlight critical knowledge gaps, including the evolutionary rationale for moonlighting ACs, precise signal transduction mechanisms, and functions of non-canonical cyclic nucleotides. This review provides a conceptual framework for advancing plant cAMP research.

Understanding how environmental factors shape male reproductive traits is crucial for plant breeding and evolutionary biology. Here, we investigated the impact of soil nutrient availability on male reproductive traits in the wind-pollinated grass Secale cereale, leveraging the long-term 'Eternal Rye' monoculture field trial established in 1878. We analysed 552 rye individuals of a population variety and 736 rye individuals of a diverse rye panel grown under nutrient-deficient and nutrient-enriched conditions. Our results show that nutrient deficiency, compared with nutrient enrichment, significantly reduced anther length and pollen number per anther, whereas pollen size and viability remained stable or increased in the population variety. Under nutrient-rich conditions, we observed a trade-off between pollen size and number, which was absent under nutrient-deficient conditions, suggesting shifts in resource allocation strategies. Importantly, this phenotypic plasticity corresponded to changes in the underlying genetic architecture, with distinct quantitative trait loci (QTLs) detected under nutrient-deficient versus nutrient-enriched environments. These findings highlight the substantial influence of environmental plasticity on male reproductive traits and their genetic control in rye.

Plant organ initiation requires precise spatial and temporal coordination of cellular behaviors. In Arabidopsis, the gynoecium, the female reproductive structure formed by two fused carpels, is initiated after the termination of the floral meristem. Proper initiation of the carpels is crucial for ovule protection, successful fertilization, and the formation of diverse fruit structures. While the phytohormones auxin and cytokinin are known to regulate organogenesis, their interplay during the earliest stages of carpel development is not fully understood. In particular, how auxin-cytokinin crosstalk influences growth patterns that shape the emerging gynoecium remains unknown. Here, we combined confocal live imaging, hormone treatments, and hormone reporters to capture at cellular resolution the dynamic processes of cell expansion and division that drive the onset of the carpel developmental program. We show that carpel primordia initiation is driven by growth differences between the fast-expanding peripheral and slow-growing central regions, transforming the dome-shaped floral meristem into two fused carpels connected by a continuous ring of cells. Ectopic cytokinin treatments increase cell growth and division to promote an increase in the size of the carpel primordia, whereas inhibition of auxin transport has the opposite effect. Our results suggest that the interplay between auxin and cytokinin is indispensable for establishing the correct organ geometry during carpel initiation.

Wild cucumber (Echinocystis lobata) is an invasive annual vine rapidly spreading across Central European riparian zones. Its success is linked to seed dispersal, with hydrochory expected to play a major role, but the specific mechanisms are not fully understood. This study examines whether E. lobata uses a dual dispersal strategy by seed morphological differences and hydrodynamic behavior, supporting both short-distance and long-distance dispersal. Seeds were collected in autumn and early spring, and analysed for morphology, buoyancy, and hydrodynamic properties. Over 150 seeds underwent biometric measurements: digital image correlation for swelling deformation, micro-computed tomography for internal structure, and hydrodynamic properties. Approximately 23% of seeds were buoyant, with buoyant ones present in both autumn and spring seed groups. Buoyant seeds had larger surface areas and internal air cavities, contributing to lower drag and enhanced passive transport in water. Using digital image correlation and micro-computed tomography imaging, we visualized seed coat swelling patterns and quantified internal structures. Hydrodynamic experiments revealed that buoyant seeds experienced lower drag and slower acceleration. Under oscillatory flow, buoyant seeds exhibited passive propulsion at 1 Hz, indicating a resonance effect facilitating dispersal during fluctuating water flow. These findings support a dual dispersal strategy: temporal seed release and buoyancy enable both local recruitment and long-distance dispersal, likely contributing to invasive success in riparian habitats.

Pistachio (Pistacia vera) is a drought- and salinity-tolerant perennial whose fruit features a fleshy exo-mesocarp, or 'hull', that protects the kernel. Hull development and degradation are key to kernel quality, yet the anatomy and mechanisms driving hull breakdown during late-stage development remain largely unknown. Here, we show that the hull contains anatomically distinct layers of hypodermal parenchyma and filler parenchyma. Using a combination of transcriptome analyses and immunohistochemistry, we show that changes in pectin-associated gene expression and modification of this polysaccharide are involved in hull cell size increase, loss of cell-cell adhesion, and hull softening. Anatomical analysis shows that filler parenchyma expands during late-stage hull development while hypodermal parenchyma remains constant in size. Field data suggest that irrigation and humidity affect pistachio hull split, implicating a role for water status in cell expansion. In summary, the complex interplay between molecular, cellular, and environmental changes suggests that cell layer-specific modifications of the cell wall are linked to exo-mesocarp splitting, forming a model for understanding the mechanism of fruit split during ripening in non-berry fruit crops.

Grapevine (Vitis vinifera L.) buds undergo seasonal dormancy to survive unfavourable conditions and synchronize growth with environmental cues. While dormancy transitions have been widely studied in temperate woody perennials, the physiological and metabolic dynamics underlying these transitions in grapevine remain poorly understood. Our study investigates seasonal changes in the physiology and metabolism of perennating buds in V. vinifera cv. Cabernet Sauvignon, focusing on dormancy depth, respiration, sugar metabolism, and cell cycle activity. We identified three distinct phases of bud quiescence: (i) para-dormancy (early summer), characterized by active metabolism and high levels of tricarboxylic acid cycle intermediates, shikimate, and myo-inositol; (ii) endo-dormancy (late summer to autumn), where dormancy depth peaked in late summer and was marked by reduced respiration and bud water content, and a sharp decline in hexose levels with a concomitant increase in raffinose; and (iii) eco-dormancy (winter to spring), featuring increased respiration, sugar mobilization (notably sucrose, glucose, and trehalose), and reactivation of cell division, with a shift of cells into the G2 phase. Just prior to bud burst, we observed a significant accumulation of sugar-phosphates, providing evidence that supports their role in promoting bud burst also in grapevine. Our findings provide new insights into the biochemical and physiological regulation of bud dormancy and bud burst, contributing to a deeper understanding of dormancy transitions in perennial crops.

Chloroplast iron-sulfur (Fe-S) clusters, essential cofactors for Fe-S proteins, are assembled by the sulfur utilization factor (SUF) BC2D complex, but regulation of their biogenesis remains unclear. We show that during leaf senescence, SUFB transcription rapidly increases while SUFC/SUFD transcripts and the abundance of all three SUF proteins remain unchanged. Leaf necrosis with green color occurs solely when SUFB RNA interference (RNAi) is induced, and the decrease of SUFs is obviously faster in SUFB-RNAi than SUFC-RNAi lines. Furthermore, SUFB exhibits a higher turnover rate than SUFC/SUFD, which accelerates during senescence. Overexpressing SUFB elevates SUFC/SUFD/SUFBC2D levels, revealing that SUFB stabilizes SUFC/SUFD via SUFBC2D complex formation, a function SUFC lacks. Under iron deficiency, SUFB transcript level declines, whereas SUFC/SUFD transcript levels remain unchanged. Nevertheless, abundance of SUFs decreases, suggesting that the reduced amount of SUFBC2D is mediated by the down-regulation of SUFB transcription. We subsequently found that SUFs accumulated in a caseinolytic protease (CLP)-impaired mutant and exhibited resistance to degradation when cytoplasmic translation was inhibited by cycloheximide, revealing that their turnover is mediated by CLP. Moreover, SUFB, SUFC, and SUFD physically interact with CLPS1, a substrate adaptor of the CLP complex. Collectively, SUFB expression and CLP coordinately regulate Fe-S biogenesis by controlling SUFBC2D abundance, providing critical insights into plant adaption to leaf senescence and iron deficiency.