Plant Biology最新文献

Sexually deceptive orchids mimic female mating signals of their pollinators to achieve pollination. In Australia, multiple orchid genera exploit male thynnine wasps as pollinators, raising the possibility of convergent evolution of floral traits. This study investigates the chemical basis of attraction in Spiculaea ciliata and its pollinator Thynnoturneria abspiculus, uncovering the use of shared chemical attractants. Flowers of S. ciliata were collected in the field and extracted in dichloromethane and methanol. Gas chromatography-mass spectrometry (GC-MS) and field bioassays were used to identify and test candidate floral semiochemicals. Compound identity was confirmed through co-injection and peak enhancement with a synthetic standard, and behavioural responses of pollinators to candidate compounds were assessed with the aid of dummies loaded with candidate compounds. Spiculea ciliata attracts male T. abspiculus using a single semiochemical emitted from its labellum, identified as 4-hydroxy-3-(methylthio)benzaldehyde. This compound alone elicited sexual behaviours in male wasps comparable to those triggered by whole floral extracts. 4-Hydroxy-3-(methylthio)benzaldehyde is also known from distantly related Caladenia orchids and their pollinators, indicating repeated evolution of this unusual aromatic sulfurous semiochemical. These findings demonstrate convergent evolution of chemical signalling systems in sexually deceptive orchids and their thynnine wasp pollinators.

Pronounced seasonal fluctuations in Central Asian temperate deserts, where annual temperature variations can exceed 80 °C, have shaped unique environmental adaptation strategies in regional vegetation. However, it remains unclear how biological soil crusts (BSCs), a dominant desert land cover, respond to inter-seasonal hydrothermal fluctuations and whether these adaptive strategies are consistent across different crust types. This study investigated cyanobacterial, lichen and moss crusts in the Gurbantunggut Desert to explore their seasonal adaptive strategies from the perspectives of biomass dynamics and non-structural carbohydrate (NSC) allocation patterns. The results indicated that biomass in cyanobacterial and lichen crusts increased progressively from spring to the following spring, whereas moss crusts showed no significant variation. Regarding resource allocation, cyanobacterial crusts showed a steady increase in soluble sugars and the soluble sugar-to-starch ratio, suggesting they effectively utilize seasonal precipitation pulses to sequester carbon (C) for growth. In contrast, lichen and moss crusts exhibited an inverse relationship between soluble sugars and starch; specifically, during stress periods, they remobilize starch into soluble sugars to maintain cellular osmotic homeostasis. Notably, their environmental tolerances diverged: lichen crusts exhibited high thermal tolerance but were sensitive to low-temperature stress, whereas moss crusts demonstrated robust chilling tolerance but were vulnerable to heat stress. In conclusion, our findings confirm that different BSC types employ distinctive survival strategies and stress-tolerance mechanisms, suggesting a potential for seasonal ecological niche complementarity. This study provides novel insights into the physiological adaptation strategies of desert cryptogams in response to extreme environmental variability.

Global food systems are under pressure to remain stable amidst increasing uncertainty. Plant epicuticular waxes play vital roles in mitigating a range of environmental stressors, hence understanding their diversity can inform practices that sustain the large-scale production of grain crops that underpin human nutrition. This study employs a combination of gas chromatography-mass spectrometry and scanning electron microscopy to chemically and morphologically characterise the foliar epicuticular waxes from economically important monocot and dicot species. Principal component analyses are also performed to identify key wax components that distinguish species apart. Monocot epicuticular waxes were uniform in platelet morphologies and were generally richer in primary alcohols, while dicots were morphologically diverse and were generally richer in alkanes. A clear disconnect between chemical composition and morphology suggests that individual wax components cannot be used to predict leaf surface properties. The wax composition data presented here also suggests that cuticular aldehydes are not exclusive to the decarbonylation pathway, depicting a more complex regulatory framework for cuticular wax biosynthesis. This study offers a broader inter- and intra-species view of foliar wax chemistry, emphasising differences in cuticular wax biosynthetic strategies and their implications for plant-pathogen interactions. The data collected in this study provide a valuable baseline for future studies that link epicuticular wax physicochemical properties to their biological implications.

To alleviate negative effects of genetic drift on rare plants, it has been suggested to artificially increase gene flow between isolated populations and create new populations by mixing different provenances to maximize genetic variation. However, there is also a risk of outbreeding depression. We studied the effects of cross type on components of fitness in two closely related taxa, the rare rock plants Saxifraga rosacea ssp. rosacea (octoploid) and S. rosacea ssp. sponhemica (hexaploid), a Central European endemic. Using plants from 30 populations, we carried out within-population crosses (WPC), between-population crosses (BPC) and between-taxon crosses (BTC), and measured performance over two generations in a common garden. We also studied backcrosses (BTC × WPC). Seed yield of BPC and survival of offspring were higher than that of both WPC and BTC, indicating genetic load in the isolated rock populations of both taxa. However, BPC offspring showed outbreeding depression for reproduction, while BTC offspring was nearly completely sterile, and backcrosses hardly produced any seeds. The mass and germination of the seeds produced by the F₁ and the F₂, and survival of the F₂ were not negatively affected by BPC and BTC. Our results suggest caution in increasing gene flow between long-term isolated populations or mixing seeds for restoration projects. The nearly complete infertility of the F₁-plants resulting from BTC strongly supports the notion that management measures resulting in heteroploid crosses should be avoided. Moreover, the sterility of the hybrids suggests that the two taxa should be treated as separate species.

Distyly promotes cross-pollination via reciprocal herkogamy and heteromorphic self-incompatibility, and how its functionality is maintained in species with contrasting corolla morphologies is worth further study. Using eight Limonium species (four long-tubular, four short-tubular) across 25 populations from Xinjiang, China, we examined whether corolla morphology affects distylous syndrome, reproductive success and the relationship between reciprocity and pollen deposition. All species exhibited pollen-stigma dimorphism and high fruit set from inter-morph pollination but were almost sterile from selfing/intra-morph pollination. However, long-tubular and short-tubular flowers showed divergent functional strategies. Long-tubular species displayed smaller variation in herkogamy but suffered significant pollen limitation under open pollination, with fruit set markedly lower than hand cross-pollination. In contrast, short-tubular species showed greater floral morph variation, broader variation ranges in herkogamy and higher natural fruit set with no pollen limitation. Critically, in the long-tubular L. chrysocomum, lower reciprocity was associated with reduced illegitimate pollen deposition on papillate stigmas, challenging the assumption that higher precision always enhances function. These results revealed that corolla morphology modulates distyly functionality through two distinct pathways: in addition to pollen-stigma dimorphism, long-tubular flowers (L. chrysocomum) maintain distyly through optimized reciprocity; short-tubular flowers exhibit a greater reliance on dimorphism alone. Our findings highlight the role of floral architecture in shaping the ecological and evolutionary dynamics of distyly.

Continuous cropping obstacles threaten sustainable agriculture. Phthalic acid (PA) is a key autotoxin in pepper. This study investigated the physiological mechanisms and agronomic benefits of exogenous silicon (Si) in alleviating PA stress in pepper. Pepper seedlings grown in soilless substrate culture were exposed to 2 mM PA with or without Si (0-2 mM). Growth, root architecture, photosynthesis and redox metabolism were analysed. A field trial assessed yield and fruit quality. PA stress induced an atypical redox response: suppressed reactive oxygen species accumulation and antioxidant system impairment. Exogenous Si alleviated these effects. The 1 mM Si treatment increased plant height, stem diameter and leaf number by 53.4%, 16.8% and 35.3%, respectively. Si restored antioxidant capacity, with 2 mM Si increasing leaf superoxide dismutase activity by 289.7% and 1.5 mM Si decreasing root H₂O₂ content by over 50%. The 1.5 mM Si treatment also reversed PA-induced photosynthetic suppression, numerically increasing net photosynthetic rate by 381.0% and increasing chlorophyll content by 25.8%. Field validation showed that 1 mM Si reversed PA-induced yield loss (restoring to control levels), improved fruit quality and reduced symptom incidence. Exogenous sodium silicate (Na₂SiO₃) effectively mitigates PA-induced phytotoxicity by rebalancing redox homeostasis, enhancing photosynthesis and improving root growth. However, the specific contribution of Si versus co-supplied Na⁺ requires further verification. This study demonstrates the potential of sodium silicate as a sustainable soil amendment to enhance pepper tolerance under intensive cultivation.

Sugarcane (Saccharum spp.) is an important crop for food and energy security. Identifying SNPs and genes associated with sugarcane yield and related traits is crucial for developing high - yielding sugarcane cultivars through molecular breeding. Here, we measured nine phenotypic traits across 160 sugarcane genotypes and employed multiple statistical models (namely MLM, CMLM, MLMM, FarmCPU and SUPER) in GWAS to identify stable and pleiotropic loci. A total of 200 SNPs corresponding to 137 QTLs were detected to be significantly associated with nine traits using multiple statistical models, among which 18 QTLs were consistently identified by two or more models. Notably, the SNP S9A_47793177 on chromosome 9A showed the strongest association with phenotypic variation in aboveground biomass, with a phenotypic explanation rate of 70.54%. Additionally, several QTLs significantly associated with tillering - related traits were identified, suggesting that these QTLs may play crucial roles in the regulation of tillering. The QTLs and SNPs identified in this study provide a significant foundation for molecular marker - assisted breeding in sugarcane. This advancement can significantly enhance the efficiency of genetic improvement for sugarcane yield and tillering - related traits.

Heteranthery refers to the presence of morphologically distinct stamens within a flower. Previous studies have focused on morphological matching between floral structures and pollinator body size and on the division-of-labour hypothesis (i.e. feeding pollen as a reward and pollinating pollen as a male gametophyte). However, little attention has been paid to when each stamen type presents pollen, despite the importance of phenological matching in determining pollen transport frequency. We hypothesize that morphological and phenological matching affect the qualitative (pollen transfer efficiency) and quantitative (encounter frequency) components of pollen transport, respectively. To test this hypothesis, we first examined male fertility of pollen produced by dimorphic stamens in heterantherous Lagerstroemia indica. Second, we compared morphological matching between floral structures and bee body size and evaluated its consequences for pollen transport efficiency in large carpenter bees and small honeybees. Third, we assessed phenological matching by examining diurnal patterns of anther dehiscence and bee activity and their correspondence. Flowers exhibited clear functional differentiation: feeding pollen contributed less to male success due to lower fertility. Carpenter bees, whose body size matched floral morphology, more effectively transferred pollinating pollen via dorsal deposition, whereas honeybees accumulated feeding pollen ventrally with limited pollination success. Dehiscence of pollinating anthers began early in the morning, coinciding with carpenter bee activity and continued gradually throughout the day. Together, our study reframes heteranthery as multidimensional matching strategy in which phenology governs encounter to pollinators and morphology governs the consequence of pollen transport.

Insufficient light intensity diminishes stem mechanical strength of Paeonia lactiflora, adversely affecting the quality of cut flowers. However, the underlying mechanisms remain poorly understood. Through anatomical analysis and matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI MSI) combined with LC-MS, the shading-induced changes of morphology and metabolism in fibre cells of P. lactiflora stems were comprehensively characterized for the first time. The results showed that shading inhibited secondary cell wall (SCW) thickening in fibre cells, leading to thinner SCWs and low stem mechanical strength. A total of 931 metabolites were detected in the full-sun and shade groups of P. lactiflora stem sections by MALDI MSI, and 25 significant differential metabolites were identified in the stem fibre cell zones by MS/MS fragmentations. The shading-induced differential metabolites in the fibre cell zones were primarily concentrated on various secondary metabolites with antioxidant defence properties, with their synthesis triggered by shade stress. It indicated that shading reduced P. lactiflora stem mechanical strength by inhibiting fibre SCW thickening, and this inhibition was closely correlated with an enhanced synthesis of defence metabolites in the fibre cells. This study lays a foundation for elucidating the cytological mechanism underlying shading that affects stem mechanical strength.

Sclerophyllous plants present a suite of traits, including small, leathery leaves with thick cuticles, dense trichomes and sclerified tissues, which are often accompanied by high levels of secondary metabolites. Although these features are generally associated with protection and defence, they do not necessarily deter gall-inducing organisms. In fact, some gall inducers may exploit the structural and chemical complexity of sclerophyllous tissues to develop protective and nutrient-rich microhabitats. This appears to be the case for eriophyid mites (Acari: Eriophyidae) that induce galls on the leaves of Crinodendron patagua Mol. (Elaeocarpaceae), a sclerophyllous species endemic to Chile and characteristic of coastal Mediterranean forests. We hypothesized that these mites exploit and enhance the morphoanatomical and chemical traits of C. patagua sclerophyllous leaves to induce the formation of galls that function as protective, nutrient-enriched microhabitats in the stressful Mediterranean-type climate of central Chile. Anatomical, cytohistometric, histochemical and spectrophotometric analyses were performed on galled and non-galled leaves to evaluate changes in anatomical structure, primary metabolites (proteins and reducing sugars) and secondary metabolites (polyphenols). The results revealed that mites induce anatomical changes that favour progeny development, including hypotrophy and thinning of adaxial epidermal cell walls rich in cellulose and hemicellulose and the accumulation of proteins and reducing sugars in these nutritive cells. In parallel, lignified trichomes redifferentiated at the opening of the gall, abaxial epidermal cells exhibited hypertrophy and thickened walls, and the polyphenol content increased in gall tissues. Some sclerophyllous characteristics were intensified, whereas others remained unchanged. Gall development in C. patagua selectively reprograms structural and biochemical traits to meet the nutritional and protective needs of eriophyid mites, partially supporting our original hypothesis.