Bud Development Research Articles

Physiological and metabolic analyses reveal the proline-mediated flowering delay mechanism in Prunus persica.

Peaches are susceptible to various environmental stresses. Particularly in late spring, freezing temperatures can damage peaches and consequently, affect their productivity. Therefore, flowering delay is a prominent strategy for avoiding spring frost damage. Our previous study confirmed that treatment with 5% sodium alginate and 100 mM CaCl2 (5AG) to avoid frost damage during the blooming stage delays flowering. To reveal the flowering delay mechanism of peaches, this study systematically analyzed the modification of amino acid profiles in control and 5AG-treated peach plants at different day intervals. Our findings indicate that arginine (Arg), glutamate (Glu), and proline (Pro) levels differed between the control and 5AG-treated peach shoots throughout the phenological development of flower buds. Furthermore, two amino acids (Arg and Glu) are involved in the Pro pathway. Thus, using a computational metabolomics method, Pro biosynthesis and its characteristics, gene ontology, gene synteny, cis-regulatory elements, and gene organizations were examined to decipher the involvement of Pro metabolism in peach flowering delay. In addition, qRT-PCR analysis revealed the transcriptional regulation of Pro-related and flowering-responsive genes and their role in flowering delay. Overall, this pilot study provides new insights into the role of Pro in the flowering delay mechanisms in Prunus persica through 5AG treatment.

From buds to shoots: insights into grapevine development from the Witch's Broom bud sport.

Bud sports occur spontaneously in plants when new growth exhibits a distinct phenotype from the rest of the parent plant. The Witch's Broom bud sport occurs occasionally in various grapevine (Vitis vinifera) varieties and displays a suite of developmental defects, including dwarf features and reduced fertility. While it is highly detrimental for grapevine growers, it also serves as a useful tool for studying grapevine development. We used the Witch's Broom bud sport in grapevine to understand the developmental trajectories of the bud sports, as well as the potential genetic basis. We analyzed the phenotypes of two independent cases of the Witch's Broom bud sport, in the Dakapo and Merlot varieties of grapevine, alongside wild type counterparts. To do so, we quantified various shoot traits, performed 3D X-ray Computed Tomography on dormant buds, and landmarked leaves from the samples. We also performed Illumina and Oxford Nanopore sequencing on the samples and called genetic variants using these sequencing datasets. The Dakapo and Merlot cases of Witch's Broom displayed severe developmental defects, with no fruit/clusters formed and dwarf vegetative features. However, the Dakapo and Merlot cases of Witch's Broom studied were also phenotypically different from one another, with distinct differences in bud and leaf development. We identified 968-974 unique genetic mutations in our two Witch's Broom cases that are potential causal variants of the bud sports. Examining gene function and validating these genetic candidates through PCR and Sanger-sequencing revealed one strong candidate mutation in Merlot Witch's Broom impacting the gene GSVIVG01008260001. The Witch's Broom bud sports in both varieties studied had dwarf phenotypes, but the two instances studied were also vastly different from one another and likely have distinct genetic bases. Future work on Witch's Broom bud sports in grapevine could provide more insight into development and the genetic pathways involved in grapevine.

Description of Phenological Events of Persian Walnut (Juglans regia L.) according to the Extended BBCH Scale and Historical Scales

Walnut trees are grown worldwide for their edible fruits, which have high nutritional value. To address climate change, researchers have studied walnut phenology to create cultivars adapted to warmer climates. The objective of this study is to propose a scale for phenological Persian walnut observations using the Biologische Bundesanstalt, Bundessortenamt, und CHemische Industrie (BBCH) codification and alignment with historical alphameric scales. Here, the principal growth stages (PGSs) of Persian walnut (Juglans regia L.) are described using stages from a previously available alphanumeric scale. This standardised phenological scale describes Persian walnut growth from the dormant vegetative state through reproductive budding and senescence. This phenological scale is expected to increase the efficiency of walnut phenological monitoring. Fifty-seven stages are used to describe the life cycle of Persian walnut in this BBCH scale. Of these 57 stages, 3 stages are dedicated to seed germination (PGS-0), 4 stages are dedicated to bud development (PGS-0), 7 stages are dedicated to leaf development (PGS-1), 4 stages are dedicated to stem elongation (PGS-3), 8 stages are dedicated to inflorescence emergence (PGS-5), 5 stages are dedicated to male flowering (PGS-6), 5 stages are dedicated to female flowering (PGS-6), 5 stages are dedicated to fruit development (PGS-7), 12 stages are dedicated to fruit ripening (PGS-8), and 4 stages are dedicated to leaf senescence (PGS-9).

Integrative Metabolomic and Transcriptomic Analysis Elucidates That the Mechanism of Phytohormones Regulates Floral Bud Development in Alfalfa.

Floral bud growth influences seed yield and quality; however, the molecular mechanism underlying the development of floral buds in alfalfa (Medicago sativa) is still unclear. Here, we comprehensively analyzed the transcriptome and targeted metabolome across the early, mid, and late bud developmental stages (D1, D2, and D3) in alfalfa. The metabolomic results revealed that gibberellin (GA), auxin (IAA), cytokinin (CK), and jasmonic acid (JA) might play an essential role in the developmental stages of floral bud in alfalfa. Moreover, we identified some key genes associated with GA, IAA, CK, and JA biosynthesis, including CPS, KS, GA20ox, GA3ox, GA2ox, YUCCA6, amid, ALDH, IPT, CYP735A, LOX, AOC, OPR, MFP2, and JMT. Additionally, many candidate genes were detected in the GA, IAA, CK, and JA signaling pathways, including GID1, DELLA, TF, AUX1, AUX/IAA, ARF, GH3, SAUR, AHP, B-ARR, A-ARR, JAR1, JAZ, and MYC2. Furthermore, some TFs related to flower growth were screened in three groups, such as AP2/ERF-ERF, MYB, MADS-M-type, bHLH, NAC, WRKY, HSF, and LFY. The findings of this study revealed the potential mechanism of floral bud differentiation and development in alfalfa and established a theoretical foundation for improving the seed yield of alfalfa.

Effectiveness of Nanoformulated Plant Growth Regulators in the Production and Propagation of High-value Crops and Ornamentals

Among the major classes of plant hormones, auxins, gibberellins, and cytokinins are widely used for plant propagation. These hormones influence the physiological and developmental processes of plants such as root initiation, apical dominance, seed germination, leaf expansion, and development of buds, flowers, and fruits. Its exogenous application was found to significantly improve the growth of several important plants. This study aimed to determine the effectiveness of plant growth regulators (PGRs) derived from naturally occurring plant growth-promoting bacteria (PGPBs) in the production and propagation of selected crops. In this study, indole- 3-acetic acid (IAA) and gibberellic acid (GA) were extracted from naturally occurring PGPB Bacillus sp. The extracted hormone was nanoformulated for controlled release and increased uptake in plants. The nanoformulated hormones were applied in the propagation of coffee and the production of eggplant and ornamentals. Results showed that the application of nanoformulated IAA (Nano-IAA) significantly increased the survival rate of coffee compared to the commercially available auxin. Nano-IAA increased the germination rate of eggplant in acidic soil and root emergence of Bougainvillea over the negative control (water) but was comparable to that of the commercially available auxin. The nanoformulated GAs and commercially available

Model for predicting apple bloom date based on bud response experiments in controlled environments

Climate change affects crop phenology, and this has raised interest in phenology models. Most previous studies have determined the functions and parameters of phenology models through calibrations based on observed historical bloom dates under field conditions. However, if all the functions and parameters are determined through bud response experiments in controlled environments, it becomes possible to develop a model that is independent of observation in specific regions and has a small risk of overfitting. Hence, we grew potted ‘Fuji’ apple trees under fully temperature-controlled condition to quantify the temperature response of endodormancy release, flower bud development, and their interaction to determine the functions and parameters of models. The optimum temperature to release endodormancy was between –3 °C and 6 °C, and it was not released at temperatures ≥12 °C. The developmental rate of the flower bud increased with increasing chilling treatment time at 6 °C; however, it did not change over 2000 h The relationship between the temperature and developmental rate was exponential for the ecodormancy stage. The models constructed from these experimental results were validated using a dataset of historical bloom dates observed under three different climatic field conditions in Japan. The results demonstrated that, regardless of whether the region was cold or warm, the overlap model can predict bloom dates with accuracy, whereas the sequential model can predict bloom dates with accuracy only in cold regions. The overlap model in which the functions and parameters are fixed through bud response experiments in controlled environments, is expected to be applicable for predictions spanning diverse temperature conditions in global apple-growing regions, including future temperature scenarios, without succumbing to overfitting.

Transcriptomics and metabolomics analysis revealed the regulatory network of apical buds development in lotus (Nelumbo nucifera Gaertn.)

As a perennial ornamental plant, lotus will begin to become dormant in the face of adverse environmental conditions. The dormancy and apical buds development of lotus are of great significance in regulating the flowering period, storage and reproduction of the lotus rhizome, but the related regulatory mechanisms have not been reported. In this study, we sampled the lotus apical buds at 0 d, 12 d and 24 d after planting, and determined that the lotus could complete the dormancy releaseprocess at 12 days after planting. The monitoring of physiological indexes, hormone levels and transcriptome sequencing of 9 samples in three periods were carried out. It was found that the contents of carbohydrates and hormones changed significantly during apical buds development. Transcriptome analysis also showed that a large number of differentially expressed genes were enriched in hormone synthesis and signal transduction pathways, starch and sucrose metabolism pathways, and lipid metabolism pathways, these genes may be involved in the development of lotus apical buds. Subsequently, we analyzed the differential transcription factors during apical buds development and screened a key differential gene NnHSP18.2. NnHSP18.2 is a heat shock protein (HSP) family gene specifically expressed on apical buds, encoding a protein of 160 amino acids with a conserved α-crystallin domain (ACD) domain. Overexpression of NnHSP18.2 can inhibit Arabidopsis seed germination. These results are of great significance for exploring the molecular mechanism of lotus apical buds development and actively promoting the development of the lotus industry.

Research Progress on Forest Eco-Product Value Realization and Eco-Industry: The Inspiration for Planted Forests in Karst Desertification Control

Karst desertification (KD) is a phenomenon in which the surface of the karst region presents a landscape similar to desertification, which restricts the social development of the karst region. How to develop values based on karst desertification control is the focus of current research, with the continuous promotion of karst desertification control (KDC). Planted forests for KDC are an important part of the value realization of ecological products (EPs) and ecological industry (EI) in karst areas. The statistical analysis of 265 relevant papers in this paper shows the following: (1) the literature focuses on EP and EI research; (2) the overall research shows a year-on-year growth trend. It includes three stages: budding (2001–2006), fluctuating growth (2007–2015) and rapid development (2016–2023), with 6, 58 and 211 articles published in each stage, respectively; (3) China is the country with the largest number of articles published, followed by the United States and then Canada, accounting for 47.74%, 11.93% and 6.17%. This paper summarizes the landmark results and key scientific issues to be solved in the study directions of EP supply capacity, EP value accounting, eco-products value realization (EPVR) and EI, taking into account the above results.

The gustin gene variation at rs2274333 and PROP taster status affect dietary fat perception: a stepwise multiple regression model study

Gustin, a trophic factor for taste bud development, and its polymorphism at rs2274333 influence taste perception of 6-n-propylthiouracil (PROP) and fungiform papillae (FP) density. The PROP taster status affects dietary fat sensing and body composition. However, there is a paucity of research on the gustin genotype with dietary fat perception, PROP tasting ability, and body mass index (BMI). Thus, taste sensitivity to fat and bitterness was evaluated in 178 healthy individuals. The general labeled magnitude scale was used to determine suprathreshold taste intensity ratings, whereas the alternative forced choice approach was used to estimate the taste-sensing ability. The FP density was assessed by applying blue-colored food dye over the anterior region of the tongue. Restriction fragment length polymorphism was used to detect the genetic polymorphism (rs2274333) in the carbonic anhydrase VI (CA-VI) gene. Fisher's chi-square analysis showed that the CA-VI genotype and allelic frequencies significantly correlated (p<0.001) with the PROP taster status and BMI. Healthy individuals with AA genotypes of the CA-VI polymorphism and PROP super-tasters demonstrated stronger gustatory sensitivity for linoleic acid (LA) with greater FP density in comparison to individuals with AG/GG genotypes and other PROP taster groups. Stepwise forward multiple regression analysis indicates that BMI and PROP taster status significantly influence the LA sensing ability. The suprathreshold intensity rating for LA was also significantly impacted by PROP taster status and CA-VI genotypes, with a variation of 73.3%. Overall, our findings show a relationship between the taste papillae environment and the CA-VI genetic mutation at rs2274333, which influenced the gustatory preference for dietary fat and bitter taste.

Overcoming Dormancy in Prunus Species under Conditions of Insufficient Winter Chilling in Israel.

The phenomenon of dormancy and the evolutionary causes for its development are presented together with the effects of the climatic factors: temperature and light. Shade and darkness have been found to enhance bud breaking in peach. The effects of various temperatures on chilling accumulation, chilling negation and chilling enhancement are described. The way these are computed in the face of global warming is explained, using the dynamic model. When natural chilling is less than that required, there are ways of compensation, up to a certain level. Various horticultural, physical and chemical means to achieve this are described, including bending branches, reducing vegetative vigor, shading the orchard, sprinkling to reduce daytime temperature and the application of various chemicals to break dormancy. When winter chilling is markedly reduced and temperatures increase considerably, the use of dormancy avoidance is suggested in frost-free places. This technique can induce a new growing cycle by avoiding dormancy altogether. However, the best approach is to breed high-quality cultivars requiring much less chilling. Another aspect discussed in this work, independent of the chilling requirement, is the negative effect of heat spells in winter and spring on the abnormal development of flower buds, leading to a low level of the stone fruit set and a reduced yield.

Comprehensive study on in vitro propagation of some imported peach rootstocks: in vitro explant surface sterilization and bud proliferation

The present study was conducted in the Laboratory of Tissue Culture, Horticulture Department, Faculty of Agriculture, Damietta University, Egypt. The objective of this study was to establish a micropropagation protocol suitable for three imported peach rootstocks: Okinawa (P. persica), Nemared (P. persica × P. davidiana) × P. persica), and Garnem (P. dulcis × P. persica) in vitro. The results showed that soaking the explants in sodium hypochlorite (NaOCl) at 20% for 15 min produced the highest responsiveness (82.81%), survival (96.61%), with the lowest mortality (3.14%) and contamination (0.24%). Explants of the Garnem genotype had the best response (89.12%), survival (90.62%), lowest mortality (0.00%), and highest contamination (9.37%) when compared to the other genotypes. In comparison with axillary buds, the shoot tip displayed the highest responsiveness, survival, and death (100, 87.40, and 12.59%, respectively), as well as the least significant contamination (0.00%). Additionally, the percentages of responsive, survived, dead, and contaminated explants at the various collection dates varied significantly. The 6-benzylaminopurine (BAP) concentrations used (3 to 5.0 mg/L) demonstrated similar behavior in terms of in vitro proliferation, with rates of 3.77 to 6.11, 4.33 to 8.88, and 3.33 to 7.44 shoot numbers per explant for the Okinawa, Nemared, and Garnem peach rootstocks, respectively, indicating that the number of shoot proliferations is genotype-dependent. Additionally, using 5.0 mg/L BAP in combination with 0.2 mg/L IBA significantly increased average shoot proliferation (96.29%), number of shoots per explant (7.48), and average leaf number/explant (16.33) compared to the other treatments. Based on these results, adventitious bud development was enhanced during in vitro multiplication of the Okinawa, Nemared, and Garnem peach rootstocks by the synergistic interaction of indole-butyric acid (IBA) and 6-benzylaminopurine (BAP).

DIA-based proteome profiling with PRM verification reveals the involvement of ER-associated protein processing in pollen abortion in Ogura CMS cabbage

Ogura cytoplasmic male sterility (Ogura CMS) is extensively applied in hybrid seed production in cruciferous crops. However, the post-transcriptional molecular basis of Ogura CMS in cruciferous crops remains elusive. Here, a data-independent acquisition-based proteomic approach coupled with a parallel reaction monitoring-based targeted proteomic assay was used to analyze the proteome dynamics of Ogura CMS cabbage line RM and its maintainer line RF during floral bud development to obtain insights into the mechanism underlying Ogura CMS in cruciferous crops. A total of 9 162 proteins corresponding to 61 464 peptides were identified in RM and RF floral buds. The proteomic fluctuation of RM was weaker than that of RF. Differences in protein expression between RM and RF gradually enlarged with floral bud development. Fifteen continually up-regulated and eight continually down-regulated proteins were found in RM relative to RF throughout floral bud development. Differentially expressed proteins between RM and RF during floral bud development were implicated in the endoplasmic reticulum (ER)-associated protein processing pathway, in which most of them exhibited down-regulated expression in RM. These data suggest that ER-associated protein processing may be involved in pollen abortion in Ogura CMS cabbage by inhibiting the expression of critical factors. Our findings not only deepen the understanding of the molecular mechanisms of Ogura CMS in cruciferous crops but also provide better guidance for applying Ogura CMS in the hybrid breeding of cruciferous crops.

Auxin and carbohydrate control flower bud development in Anthurium andraeanum during early stage of sexual reproduction

BackgroundFlower buds of Anthurium andraeanum frequently cease to grow and abort during the early flowering stage, resulting in prolonged planting times and increased commercialization costs. Nevertheless, limited knowledge exists of the mechanism of flower development after initiation in A. andraeanum.ResultsIn this study, the measurement of carbohydrate flow and intensity between leaves and flowers during different growth stages showed that tender leaves are strong sinks and their concomitant flowers are weak ones. This suggested that the tender leaves compete with their concomitant flower buds for carbohydrates during the early growth stages, potentially causing the abortion of the flower buds. The analysis of transcriptomic differentially expressed genes suggested that genes related to sucrose metabolism and auxin response play an important role during flower bud development. Particularly, co-expression network analysis found that AaSPL12 is a hub gene engaged in flower development by collaborating carbohydrate and auxin signals. Yeast Two Hybrid assays revealed that AaSPL12 can interact with AaARP, a protein that serves as an indicator of dormancy. Additionally, the application of exogenous IAA and sucrose can suppress the expression of AaARP, augment the transcriptional abundance of AaSPL12, and consequently expedite flower development in Anthurium andraeanum.ConclusionsCollectively, our findings indicated that the combination of auxin and sugar signals could potentially suppress the repression of AaARP protein to AaSPL12, thus advancing the development of flower buds in Anthurium andraeanum.

H2O2 promotes trimming-induced tillering by regulating energy supply and redox status in bermudagrass.

Tillering/branching pattern plays a significant role in determining the structure and diversity of grass, and trimming has been found to induce tillering in turfgrass. Recently, it has been reported that hydrogen peroxide (H2O2) regulates axillary bud development. However, the role of H2O2 in trimming-induced tillering in bermudagrass, a kind of turfgrass, remains unclear. Our study unveils the significant impact of trimming on promoting the sprouting and growth of tiller buds in stolon nodes, along with an increase in the number of tillers in the main stem. This effect is accompanied by spatial-temporal changes in cytokinin and sucrose content, as well as relevant gene expression in axillary buds. In addition, the partial trimming of new-born tillers results in an increase in sucrose and starch reserves in their leaves, which can be attributed to the enhanced photosynthesis capacity. Importantly, trimming promotes a rapid H2O2 burst in the leaves of new-born tillers and axillary stolon buds. Furthermore, exogenous application of H2O2 significantly increases the number of tillers after trimming by affecting the expression of cytokinin-related genes, bolstering photosynthesis potential, energy reserves and antioxidant enzyme activity. Taken together, these results indicate that both endogenous production and exogenous addition of H2O2 enhance the inductive effects of trimming on the tillering process in bermudagrass, thus helping boost energy supply and maintain the redox state in newly formed tillers.

Two key enzyme genes associated with ethylene bio-synthesis, LbACS and LbACO, are involved in the regulation of lily flower senescence

Ethylene plays an important role in regulating the growth and development of flowers and determines the flower life span of ornamental plants. In this study, the lily variety 'Manissa' was used to elucidate the mechanism associated with the regulation of lily senescence by the genes for 1-aminocyclopropane-1-carboxylic acid synthetase (ACS) and 1-aminocyclopropane-1-carboxylic acid oxidase (ACO), which are key enzymes in the ethylene biosynthesis pathway. The results showed that ethylene release increased, the relative water content first increased and then decreased, and relative conductivity continuously increased as lily bud development progressed. LbACS1 transcription was highest at the blooming stage, LbACS7 transcription was highest at the green bud stage, and LbAC03 and LbAC04 levels both peaked at the yellow bud stage and the blooming stage. After treating cut lily flowers with ethephon and ethylene inhibitor 1-methylcyclopropene (1-MCP), the results showed that ethephon promoted the senescence of cut flowers, ethylene release, and the transcription levels of the four Lb genes. 1-MCP treatment also delayed the aging of cut flowers, but reduced ethylene release and inhibited the transcription of LbAC03 and LbAC04 when the treatment was applied during the later stages of bud development. This study provided evidence for the role of ethylene and the functions of LbACS and LbAC0 in the aging process associated with cut lily flowers.

Phenological growth stages of cardamom (Elettaria cardamomum Maton): Detailed identification and description using the extended BBCH scale

AbstractCardamom (Elettaria cardamomum Maton) is an important spice crop with high market value. In this study, we describe the phenological growth stages of cardamom using a three‐digit extended Biologische Bundesanstalt, Bundessortenamt und CHemische Industrie (BBCH) scale, which includes eight principal growth stages, comprising four vegetative, two reproductive and two capsule development stages. Additionally, we identified 45 secondary stages within these principal growth stages, providing a comprehensive characterisation of the crop's growth progression, including bud development, leaf emergence, tillering and shoot development, while the reproductive stages included inflorescence emergence and flowering. The capsule development stage details the maturation process of capsules. The study also highlights the parallel occurrence of tillering, shoot development and inflorescence emergence stages during specific growth phases. The knowledge of growth stages facilitates timely interventions, optimising crop management strategies and enhancing overall crop productivity. Additionally, these findings offer valuable insights for breeding programmes and the selection of superior genotypes, contributing to the sustainable cultivation and economic viability of cardamom as an important export‐oriented spice crop.Highlights BBCH scale provides uniform coding for different growth stages of cardamom. Identified and described eight principal growth stages (PGS). PGS comprises of 4 vegetative, 2 reproductive and 2 capsule development stages. 45 secondary stages were identified within 8 principal growth stages. Tillering, shoot development and inflorescence emergence occurs parallelly.

Phenological growth stages of Xanthoceras sorbifolium Bunge: Codification and description according to the BBCH scale

Xanthoceras sorbifolium Bunge is a kind of unique oil tree species found in northern China that has high ecological, ornamental, and economic value. Its seed oil is not only a high-quality edible oil well supplied with unsaturated fatty acids but also a superior raw material for biodiesel production. In the present study, the different phenological growth stages of X. sorbifolium were characterized according to the Biologische Bundesanstalt, Bundessortenamt und CHemische Industrie (BBCH) scale. Eight principal growth stages were described for the bud, leaf and shoot development; inflorescence emergence and flowering; fruit development and maturity, together with senescence and beginning of dormancy. Meanwhile forty-two secondary growth stages were described in detail. Illustrative pictures with a codification were provided to better define and describe these phenological growth stages. Phenological records from two growing seasons were used to create a schematic representation of the principal growth stages. This study provides a beneficial reference for general orchard management, scientific research, and cultivation of new cultivars.

Identification of Olives Using In-Field Hyperspectral Imaging with Lightweight Models.

During the growing season, olives progress through nine different phenological stages, starting with bud development and ending with senescence. During their lifespan, olives undergo changes in their external color and chemical properties. To tackle these properties, we used hyperspectral imaging during the growing season of the olives. The objective of this study was to develop a lightweight model capable of identifying olives in the hyperspectral images using their spectral information. To achieve this goal, we utilized the hyperspectral imaging of olives while they were still on the tree and conducted this process throughout the entire growing season directly in the field without artificial light sources. The images were taken on-site every week from 9:00 to 11:00 a.m. UTC to avoid light saturation and glitters. The data were analyzed using training and testing classifiers, including Decision Tree, Logistic Regression, Random Forest, and Support Vector Machine on labeled datasets. The Logistic Regression model showed the best balance between classification success rate, size, and inference time, achieving a 98% F1-score with less than 1 KB in parameters. A reduction in size was achieved by analyzing the wavelengths that were critical in the decision making, reducing the dimensionality of the hypercube. So, with this novel model, olives in a hyperspectral image can be identified during the season, providing data to enhance a farmer's decision-making process through further automatic applications.

Bud development, flower phenology and life history of holoparasitic Rafflesia cantleyi.

Despite being the world's largest single-flower, Rafflesia's biology and life history are still poorly understood due to its cryptic growth strategy on Tetrastigma vines. Previous studies have been mostly short-term, contrary to Rafflesia's long development period before blooming. Bud development and flower phenology of R. cantleyi was studied in a dipterocarp forest in Lata Jarum, Peninsular Malaysia. Seven populations, consisting of 247 buds, were monitored fortnightly for 65months in two discrete studies between 2009 and 2018. The bud size distribution of R. cantleyi is dynamic, progressively changing from small flower buds to larger buds before flowering. Buds < 5.0cm across had the slowest growth and highest mortality rates, while those > 15.0cm across demonstrated accelerated growth. The bud growth profiles of the same site clustered distinctively regardless of sex with successful blooming rate that varied greatly between sites, prompting speculation about their relatedness to the sites' physical attributes. We reported the first female-dominated population in Rafflesia's life history. Rafflesia cantleyi's blooming rate at Lata Jarum is moderate to high, with non-seasonal flowering phenology as evident by the lack of synchronisation and consistency between flowering and local rainfall patterns. Based on the field data of the present study and the published information of other Rafflesia species, R. cantleyi's life cycle was estimated between 4.0 and 5.3years. Our findings further explain Rafflesia's biology and life history and highlight the gap in knowledge of the natural habitats on the endoparasite's growth and fate potentially for future conservation and study.

Physiological, biochemical and transcriptomic studies reveal the mechanisms promoting tiller bud growth under high temperature conditions in japonica rice

High temperature (HT) negatively impacts the initiation and development of tiller buds in japonica rice, resulting in a substantial decrease in yield. However, the physiological and molecular mechanisms alleviating the inhibition of HT on the growth of tiller buds in japonica rice remain elusive. Hence, this study aimed to dissect the underlying mechanisms of normal tiller buds’ growth under HT in japonica rice through comparative physiological, biochemical and transcriptomics analyses of two contrasting varieties, ‘Changgeng 225’ (‘CG225’, heat-tolerant) and ‘Zhonghua 11’ (‘ZH11’, heat-sensitive). Compared with ‘ZH11’, the tiller number of ‘CG225’ decreased less under HT stress. ‘CG225’ outperformance over ‘ZH11’ was due to higher activities of the antioxidant enzymes (SOD, CAT, POD and APX), as well as higher activities of the key enzymes involved in carbon and nitrogen metabolism (NR, GOGAT, GS, GDH, SS and SPS) in tiller buds. In addition, lower contents of the tiller-inhibiting phytohormone ABA and SLs, and higher contents of the tiller-promoting phytohormone CK in ‘CG225’ also promoted the growth of tiller buds. Most of the significant DEGs between ‘CG225’ and ‘ZH11’ under HT conditions were assigned to chloroplast and photosynthesis. We identified potential candidate genes, including transcription factors (EP2, B3, bHLH, MYB, NAC, and WRKY), phytohormone (auxin efflux carriers and ethylene biosynthesis genes), antioxidant system (peroxidases), and sucrose pathway-related genes. Furthermore, ectopic sucrose application significantly alleviated HT inhibitory effects on tiller bud growth of ‘ZH11’ plants. Our results reveal a synergistic control of heat stress by several metabolic mechanisms in japonica rice during tillering and provide fundamental resources for improving rice HT tolerance and production.