Journal of Experimental Botany最新文献

The performance of plant hybrids relative to line breeding types is generally associated with higher yields, better adaptation, and improved yield stability. In bread wheat (Triticum aestivum L.), however, a broad commercial success for hybrids has not been accomplished until now largely due to the low efficiency of hybrid grain production, which is highly attributable to its self-pollinating nature. To better understand how hybrid wheat grains can be produced more effectively, we investigated the influence of synchronized flowering between female (i.e. male-sterile) lines and their male cross-pollinator lines as well as of the duration of flowering on hybrid grain production. We found that synchronization of flowering in combination with the longest possible temporal overlap had the largest positive effect on hybrid grain production. However, despite sufficient spatial and temporal synchronization of flowering, we also found that some female lines had lower hybrid grain set than others, suggesting genetic differences in female floral receptivity. To better assess female receptivity, we established a new phenotyping scale of male-sterile wheat flowers that provides the floral basics for effective cross-pollination. Applying this scale in our field and greenhouse trials revealed that better performing female lines remained longer in the pollen-receptive phase.

Plant cell walls delimit cells from their environment and provide mechanical stability to withstand internal turgor pressure as well as external influences. Environmental factors can be beneficial or harmful for plants and vary substantially depending on prevailing combinations of climate conditions and stress exposure. Consequently, the physicochemical properties of plant cell walls need to be adaptive, and their functional integrity needs to be monitored by the plant. One major threat to plants is posed by phytopathogens, which employ a diversity of infection strategies and lifestyles to colonize host tissues. During these interactions, the plant cell wall represents a barrier that impedes the colonization of host tissues and pathogen spread. In a competition for maintenance and breakdown, plant cell walls can be rapidly and efficiently remodelled by enzymatic activities of plant and pathogen origin, heavily influencing the outcome of plant-pathogen interactions. We review the role of locally and systemically induced cell wall remodelling and the importance of tissue-dependent cell wall properties for the interaction with pathogens. Furthermore, we discuss the importance of cell wall-dependent signalling for defence response induction and the influence of abiotic factors on cell wall integrity and cell wall-associated pathogen resistance mechanisms.

The balance between cell growth, proliferation, and differentiation emerges from gene regulatory networks coupled to various signal transduction pathways, including reactive oxygen species (ROS) and transcription factors (TFs), enabling developmental responses to environmental cues. The primary root of Arabidopsis thaliana has become a valuable system for unravelling such networks. Recently, the role of TFs that mediate ROS inhibition of primary root growth has begun to be characterized. This study demonstrates that the MADS-box TF gene XAANTAL1 (XAL1) is an essential regulator of hydrogen peroxide (H2O2) in primary root growth and root stem cell niche identity. Interestingly, our findings indicated that XAL1 acts as a positive regulator of H2O2 concentration in the root meristem by directly regulating genes involved in oxidative stress response, such as PEROXIDASE 28 (PER28). Moreover, we found that XAL1 is necessary for the H2O2-induced inhibition of primary root growth through the negative regulation of peroxidase and catalase activities. Furthermore, XAL1, in conjunction with RETINOBLASTOMA-RELATED (RBR), is essential for positively regulating the differentiation of columella stem cells and for participating in primary root growth inhibition in response to oxidative stress induced by H2O2 treatment.

Resupination refers to the developmental orientation changes of flowers through ~180°, leaving them effectively upside-down. It is a widespread trait present in 14 angiosperm families, including the Orchidaceae, where it is a gravitropic phenomenon actively controlled by auxins. Here, we demonstrate that the passive gravitational pull on flower parts can have an additional influence on resupination. We studied a lady's slipper orchid in which some flowers naturally fail to resupinate. We conducted a manipulative experiment removing floral parts and showed that both the probability of complete resupination and the degree of flower vertical movement (from 0° to 180°) are related to the mass of floral organs. During flower development, the tip of the ovary slightly curves actively (14.75°) due to gravitropism. This promotes a lever arm effect so that the gravitational pull acting on flower mass creates a torque that bends the ovary, orienting the flower into a resupinate position that is accessible to pollinators. The role of the mass of floral organs in resupination provides new insights into flower development and its role in pollination mechanisms.

Chloroplasts play a pivotal role in the metabolism of leaf mesophyll cells, functioning as a cellular hub that orchestrates molecular reactions in response to environmental stimuli. These organelles contain complex protein machinery for energy conversion and are indispensable for essential metabolic pathways. Proteins located within the chloroplast envelope membranes facilitate bidirectional communication with the cell and connect essential pathways, thereby influencing acclimation processes to challenging environmental conditions such as temperature fluctuations and light intensity changes. Despite their importance, a comprehensive overview of the impact of envelope-located proteins during acclimation to environmental changes is lacking. Understanding the role of these proteins in acclimation processes could provide insights into enhancing stress tolerance under increasingly challenging environments. This review highlights the significance of envelope-located proteins in plant acclimation.

Root senescence remains largely unexplored. In this study, the time-course of the morphological, metabolic, and proteomic changes occurring with root aging were investigated, providing a comprehensive picture of the root senescence program. We found novel senescence-related markers for the characterization of the developmental stage of root tissues. The rapeseed root system is unique in that it consists of the taproot and lateral roots. Our study confirmed that the taproot, which transiently accumulates large quantities of starch and proteins, is specifically dedicated to nutrient storage and remobilization, while the lateral roots are mainly dedicated to nutrient uptake. Proteomic data from the taproot and lateral roots highlighted the different senescence-related events that control nutrient remobilization and nutrient uptake capacities. Both the proteome and enzyme activities revealed senescence-induced proteases and nucleotide catabolic enzymes that deserve attention as they may play important roles in nutrient remobilization efficiency in rapeseed roots. Taking advantage of publicly available transcriptomic and proteomic data on senescent Arabidopsis leaves, we provide a novel lists of senescence-related proteins specific or common to root organs and/or leaves.

Darkness is often used as an effective measure to induce leaf senescence. Although many senescence-related genes in rice have been reported, the genome-wide genetic architecture underlying leaf senescence remains poorly understood. In our study, indica and japonica rice showed contrasting responses to dark-induced leaf senescence (DILS). Genome-wide association studies (GWAS) combined with transcriptomic analyses revealed 57, 97, and 48 loci involved in the regulation of the onset, progression, and ending of DILS, respectively. Haplotype analyses showed that the senescence-related loci differentially accumulated in indica and japonica accessions and functioned additively to regulate DILS. A total of 357 candidate genes were identified that are involved in various senescence-related processes such as lipid and amino acid catabolism, photosynthesis, response to reactive oxygen species, and regulation of defence response. In addition, functional analyses of candidate genes revealed that OsMYB21 positively regulates the onset of DILS, while OsSUB1B negatively regulates its progression. Thus, our results provide new insights into the genetic regulation of DILS in rice.