AoB Plants最新文献

Mountain rye (MR: Secale strictum syn. S. montanum) is a forage grass that is considered a candidate for perennial grain development in Australia. A greater understanding of the triggers for flowering would aid the integration of this dual-purpose perennial into Australian grazing and cropping systems. The objective of this experiment was to determine the effects of cold incubation (vernalization) periods of varying duration on the grain yield, biomass production, and phenology of MR, compared to a dual purpose annual winter wheat cultivar (AW: Triticum aestivum L), and the perennial intermediate wheatgrass (IWG: Thinopyrum intermedium (Host) Barkworth & D.R. Dewey). Plants were grown in pots to a three leaf stage, before being subjected to vernalization treatments of varying length (0, 3, 5, 7, 9, and 11 weeks) using a growth chamber set to 5°C and 10 hour lighting. The plants were then transferred to a glasshouse set to 22°C and a minimum of 10 hour lighting. Glasshouse daylengths increased as the season progressed from winter into spring and summer. Exposure at ≤5°C for 5 weeks in MR optimized reproductive development, compared to approximately 3 weeks for winter wheat and 11 weeks for IWG. Both MR and IWG appear to have a dual induction requirement, needing a period of cold exposure and short days, followed by daylengths of 12-13 hours for MR, and at least 13 hours for IWG, to optimize their grain production potential. The observed higher vernalization requirement of MR, compared to AW, helps delineate the grain production potential of the tested germplasm in current wheat-growing areas of temperate Australia. Reproductive tiller percentages were much higher and developed earlier in AW compared to the perennial cereals. Improving the ratio and timing of reproductive tillers development in perennial cereals should be a target if grain yields are to be improved.

The flowering phenology of many closely related species in the Brazilian Cerrado coincides with the onset of the rainy season, where sequential flowering often occurs with some overlap. Transitioning from solitary flowering to coflowering with congeneric species may alter the pollination environment, affecting pollen delivery and deposition patterns. Coflowering among conspecifics concurrently requires pollination niche differentiation to minimize reproductive costs. This study tested these concepts in the distylous Palicourea coriacea during two flowering periods: early in the season when it flowered alone, and later with conspecific P. officinalis, also distylous. Pollination syndromes were assessed by measuring corolla length, nectar volume and sugar concentration, and reproductive organ height. Palicourea coriacea shows yellow and shorter corollas with higher sugar concentration in the nectar, while P. officinalis presents yellow to orange longer corollas with more diluted nectar, aligning with bee and hummingbird pollination syndromes, respectively, as reported in the literature. However, the species exhibited significant overlap in stigma and anthers height. The main floral visitor in the two species during the study was Bombus pauloensis. Visitation increased through the season, particularly in conspecific patches of P. coriacea, resulting in higher pollen delivery. In contrast, pollen deposition was similar or higher in congeneric patches with P. officinalis during the coflowering period. Visits to P. coriacea were higher than in P. officinalis, suggesting a bumblebee preference for the former. The study highlights the complex interplay between flowering phenology, floral traits, and pollinator behaviour in shaping reproductive outcomes and potential niche differentiation. While differences in flowering and flower morphology may prevent potential costs of pollinator sharing, the risk of reproductive interference remains significant. Future research should focus on comprehensive pollination dynamics throughout the entire flowering season, measuring pollinator behaviour, pollen dynamics and plant fitness, to further elucidate the mechanisms driving floral evolution and niche differentiation in sympatric species.

Grapevine (Vitis vinifera L.) stomata are highly sensitive to atmospheric changes and influence the tradeoff between water and carbon, as estimated by intrinsic water use efficiency (iWUE). The aim of this study was to examine how elevated CO₂ concentrations and water deficit affect the iWUE and whole plant evapotranspiration of two grapevine varieties (cv. Cabernet Sauvignon and cv. Chardonnay). Dormant cuttings were collected from a vineyard in Temecula Valley, CA, and were grown in a growth chamber under one of two CO₂ treatments: near ambient (410 ppm) or elevated (700 ppm). After 8 weeks of vegetative growth, grapevines were subjected to a well-watered (25% soil water content [SWC]) or gradual water-deficit treatment implemented over 12 days. We measured leaf gas exchange, including photosynthesis (A _net), stomatal conductance (g _s), intercellular carbon (C _i ), and calculated iWUE (A _net/g _s), as well as daily cumulative evapotranspiration per unit leaf area (g cm^-2 day^-1). Vines were harvested to determine total dry weight, root mass fraction, and nitrogen content. We found that elevated CO₂ and water deficit interactively increased the iWUE for both varieties, with Cabernet Sauvignon having 20% greater iWUE than Chardonnay at ~5% SWC. Chardonnay exhibited greater maximum conductance, and 43% more water transpired than Cabernet Sauvignon under a well-watered treatment. Chardonnay plants were also more impacted by elevated CO₂ and water-deficit treatment than Cabernet Sauvignon, exhibiting greater stomatal sensitivity under these treatments. At ambient CO₂, water deficit negatively impacted Chardonnay's photosynthesis than Cabernet Sauvignon. However, this effect was not observed at elevated CO₂. This study elucidates the intraspecific differences in stomatal behaviour, productivity, and water use of two V. vinifera L. genotypes (Cabernet Sauvignon and Chardonnay), under elevated CO₂ concentrations and short-term water deficit.

Soil heterogeneity significantly impacts the structure and function of plant communities. However, most of the previous studies only focussed on the effects of soil heterogeneity on plant populations, while the joint effects of plant interaction and soil heterogeneity on plant communities remain unclear. Thus, a manipulation experiment was done to explore the effects of soil heterogeneity and species combination on the seed germination, plant height and plant biomass, where three soil heterogeneity levels were created by varying patch sizes (small, medium, and large), and 10 species combinations were generated by growing four typical forages on the Qinghai-Tibetan Plateau (Elymus nutans, Festuca sinensis, Poa pratensis, and Vicia unijuga) either in monocultures or in mixtures. Data were analysed at three scales (at the pot scale, at the monoculture, and at the mixture scale). Results showed that with decreasing patch size, (i) at the pot scale, the seed germination and plant height in both monocultures and mixtures decreased, while the plant biomass in mixtures first decreased and then increased, and the plant biomass in monocultures decreased; and (ii) at the monoculture scale and the mixture scale, the plant height of E. nutans in the monoculture first decreased and then increased, while the plant height of the other monocultures decreased. Furthermore, the plant biomass of E. nutans in the monoculture first decreased and then increased, while the plant biomass of the rest species combination decreased. This study provides insight into the future restoration of degraded grassland in alpine meadows and the healthy management of artificial grasslands.

Plants have evolved strategies to maintain photosynthesis and mitigate tissue-damaging high light. In some dioecious seed plants, these strategies are sexually dimorphic and are linked to spatial segregation of the sexes (SSS) along light gradients. In vascular tissue-free plants (bryophytes) with separate sexes, SSS is common, but how light gradients, sexual dimorphisms, and SSS correlate is not well understood. To test if sexual dimorphisms in vegetative or sexual stages lead to light-associated SSS in bryophytes, we used Marchantia inflexa whose males occupy a wider range of light conditions, including higher light conditions, than females. We also tested if changes in development differed between sexes. We grew 25 males and 25 females in a glasshouse with clones in low and high light and assessed pigment and biomass allocation traits in vegetative and sexual thalli (analogous to leaves), representing non-sexual and sexually reproductive stages. We expected males to exhibit traits consistent with high light acclimation more than females and greater sex differences in sexual thalli due to specialization. Further, we reasoned that males would change more between stages than females. For sexual thalli, males had higher carotenoid/chlorophyll ratios (consistent with expectation), while females had higher chlorophyll a/b ratios and dry matter content (opposite from expectations). Vegetative thalli were not sexually dimorphic but were more plastic to light than sexual thalli. Overall, the stages differed more for males than females, but without regard for light. However, female stages differed more for dry matter content. Males generally need greater change in pigmentation and biomass allocation than females between stages, and we posit links for individual traits to sex function. Specialization in sexual thalli constrains their plasticity to light compared to vegetative thalli. Yet, neither sexual dimorphism in sexual thalli nor greater change between stages for males than females clearly leads to light-associated SSS.

With the rising threat to insect pollinators and the upcoming pollinator crisis, it is important to know how pollinators contribute to pollen transfer. The contributions of individual pollinator taxa to pollen transfer depend both on their abundance and on how much pollen each individual can carry, with overall importance being a multiplication of these two values. Here, we quantified pollen load across a diverse spectrum of insect pollinator taxa and variation in their abundance over 11 years. We found that, while variation in pollen load was relatively small among pollinator taxa (compared to relatively high variability among individuals within each insect taxon), the visitation levels changed significantly over the years, resulting in a high degree of variation in pollinator contributions to pollen transfer of each insect taxon at the community level. Thus, we conclude that the overall importance of pollinator taxa for pollen transfer is determined further by their abundances than by their taxon-specific capability for carrying various pollen loads. As the insect abundances vary over time and may change dramatically from year to year, our results highlight the importance of diverse and species-rich pollinator communities, as the population decline of one pollinator can be buffered by an increase in another pollinator taxa.

Plant reproductive strategies are particularly relevant on islands, where environmental constraints usually shape ecological dynamics. In this sense, the role of lizards (Lacertilia) as flower visitors and potential pollinators has been increasingly recognized. However, lizards may also consume plant reproductive tissues, potentially influenced by lizard intraspecific traits such as age and sex. This study aims to investigate, for the first time, the reproductive biology of the rare Mediterranean shrub Withania frutescens (L.) Pauquy (Solanaceae), and to assess the role of the Balearic lizard Podarcis lilfordi Günther (Lacertidae) as a potential pollinator on Na Redona islet (Cabrera archipelago, Balearic Islands). We analysed flower traits (corolla length, corolla diameter, stamen length, and pistil length) and performed flower bagging experiments with three pollination treatments (open pollination, autogamy, and cross hand-pollination) from 2018 to 2021 to unravel the plant reproductive system. Fruit set, the number of seeds per fruit, seed weight, size and viability were then assessed. Observational censuses were conducted to identify the main flower visitors and estimate their visitation frequency. Finally, we measured morphometric traits of lizards and explored potential intraspecific variation in floral use. The flowers of W. frutescens were morphologically hermaphroditic but functionally dioecious, spatially separated in unisexual individual plants. Open pollination and autogamy treatments resulted in similar fruit set, while cross hand-pollination produced the highest value. However, open pollination significantly increased seed weight and viability. Lizards were the most frequent floral visitors, accounting for 68% of visits, while insects made up the remaining 32%. Lizards played a dual role as both pollinators and florivores, with 45% of their visits potentially contributing to pollination and 55% involving florivory. Juveniles and females primarily conducted legitimate visits, whereas males -with a larger size- were more likely to consume the flowers. Our research describes, for the first time, a mixed reproductive system in W. frutescens, combining hermaphroditism with cryptic dioecy. We also provide a new example of a lizard-pollinated plant, highlighting the importance of vertebrates on island pollination as well as the influence of pollinator intraspecific variation on plant reproductive success. Further research on the reproductive and pollination systems of small, isolated plant populations is crucial, given their heightened vulnerability to disturbance and genetic inbreeding.

The covering tissue structure is important for leafless stem succulents, influencing their photosynthetic activity. Usually, the epidermis on succulent stems persists for a long time, making the stem photosynthesize as long as possible. Its persistence implies maintaining the continuity of covering tissues during bark dilatation. In most plants, dilatation is performed by developing periderm(s) to replace the epidermis. The ways of bark dilatation with delay of periderm formation remain poorly known. In the present study, we examine the structure of the juvenile and mature bark of succulent pencil tree Euphorbia tirucalli (Euphorbiaceae) to clarify the ways of dilatation of its protective tissues. The bark structure of Euphorbia tirucalli at various developmental stages was examined using light and scanning electron microscopy. The epidermis is found not only on young stems of E. tirucalli but also on the bark of its thick branches and trunk, which are up to about 6 cm in diameter. On the young stems, the stomata are sunken in long vertical grooves. On the older stems, these grooves are stretched out due to dilatation, bringing stomata to the surface. Expansion cracks, i.e. broad vertical epidermal ruptures underlaid by tightly arranged tangential strands of cortical parenchyma, appear between the stomatal zones on dilated bark. The phellogen is initiated in the depth of the cortex beneath the epidermal ruptures long after their formation. The bark dilatation by forming epidermal ruptures with delayed initiation of periderm was found for the first time. Prolonged photosynthesis in the succulent stem is the main functional benefit of such a bark dilatation method. The initiation of periderm in the depth of the cortex has not been reported in stem succulents other than a few Euphorbia species.

Euphorbiaceae is among the main angiosperm families with a high number of laticiferous species. Although many of its species remain to be studied in terms of their anatomy, chemistry, and uses, there are some of recognized economic importance due to useful secondary compounds present in the latex. Acalyphoideae, one of the three major subfamilies, has traditionally been distinguished from the rest of Euphorbiaceae by the absence of latex and laticifers. To test this long-standing assumption, we anatomically analysed 40 species in 10 genera, representing six of the nine subclades of Acalyphoideae s.s., to examine the presence of laticifers using leaf blade and petiole sections. Laticifers were observed in all the studied species and consisted of multinucleate, elongated cells with dense cytoplasm. They were articulated and branched in Acalypha, Bia, and Dalechampia; this was further confirmed by ontogenetic analyses in Acalypha accedens, A. brasiliensis, and A. poiretii. Histochemical tests revealed lipids, proteins, mucilage, and starch in laticifers. Our results demonstrate that laticifers are present and common in Acalyphoideae and thus more widespread in Euphorbiaceae than previously known. The scarcity of detailed anatomical studies, and the often imperceptible latex exudation of most Acalyphoideae, are probably the main reasons that have misled field botanists and systematists in the past.

A stable supply of transplants with floral buds is required to improve the initial yield of the June-bearing cultivars of strawberry (Fragaria × ananassa Duch.). A closed transplant production system (CTPS) enables year-round production to meet the demands for the year-round production of strawberries in plant factories. In this study, we evaluated the performance of a novel method involving the localized chilling of strawberry crowns using silicone tubes containing circulated chilled water at different temperatures (10, 15, or 20°C) at the nighttime and different chilling regimes (daytime, nighttime, or entire day) under high air temperature conditions in a CTPS in terms of floral bud differentiation. We observed that 4 weeks of localized chilling at 10 or 15^oC during the nighttime under the air temperature of 25/20°C (photo-/dark periods) and a photoperiod of 10 h promoted floral bud differentiation, whereas 6 weeks of localized chilling under the same conditions inhibited differentiation. Moreover, 4 weeks of localized chilling at 5^oC during the daytime or entire day under the elevated air temperatures of 28/21°C and an extended photoperiod of 14 h promoted floral bud differentiation, and 6 weeks of localized chilling during the entire day under the same conditions further promoted bud differentiation compared with that in the control. Plant growth was generally unaffected by the localized chilling of the crowns. The results indicate that to cope with the impacts of elevated air temperature and photoperiod conditions, the continuous localized chilling of crowns at 5^oC during the entire day for 6 weeks must be used to achieve optimal bud differentiation. These findings suggest the effectiveness of the localized chilling of the crowns for floral bud differentiation in strawberry in CTPSs, without disrupting the high-air temperature and long-day conditions required for vegetative growth.