Germination Tube Research Articles

NETWORKED2-subfamily proteins regulate the cortical actin cytoskeleton of growing pollen tubes and polarised pollen tube growth.

We have recently characterised NET2A as a pollen-specific actin-binding protein that binds F-actin at the plasma membrane of growing pollen tubes. However, the role of NET2 proteins in pollen development and fertilisation have yet to be elucidated. To further characterise the role of Arabidopsis NET2 proteins in pollen development and fertilisation, we analysed the subcellular localisation of NET2A over the course of pollen grain development and investigated the role of the NET2 family using net2 loss-of-function mutants. We observed NET2A to localise to the F-actin cytoskeleton in developing pollen grains as it underwent striking structural reorganisations at specific stages of development and during germination and pollen tube growth. Furthermore, net2 loss-of-function mutants exhibited striking morphological defects in the early stages of pollen tube growth, arising from frequent changes to pollen tube growth trajectory. We observed defects in the cortical actin cytoskeleton and actin-driven subcellular processes in net2 mutant pollen tubes. We demonstrate that NET2 proteins are essential for normal actin-driven pollen development highlighting an important role for the NET2 family members in regulating pollen tube growth during fertilisation.

Efficacy of Wickerhamomyces anomalus yeast in the biocontrol of blue mold decay in apples and investigation of the mechanisms involved

Blue mold decay is the one of most important postharvest disease of apples caused by the fungus, Penicillium expansum. This study aimed to investigate the biocontrol efficacy of the yeast, Wickerhamomyces anomalus, on postharvest blue mold decay of apples and the relative defense mechanisms. The results indicated that W. anomalus could significantly reduce the blue mold decay of apples, and the maximum inhibition was obtained when the concentration of W. anomalus was 1 × 108 cells ml−1. Furthermore, W. anomalus significantly reduced the fruit decay under ambient conditions, without generating any change in fruit quality. In vitro experiments showed that W. anomalus greatly inhibited the spore germination and germ tube elongation of P. expansum. Besides, its ease of adaptation, stable growth and potential colonization of in apple wounds or surfaces indicated that W. anomalus could compete with P. expansum for nutrients and space, leading to considerable inhibition blue mold decay. W. anomalus significantly induced the activities of polyphenol oxidase (PPO), peroxidase (POD), catalase (CAT), phenylalanine ammonia-lyase (PAL), and ascorbate peroxidase (APX) in apples. Moreover, W. anomalus increased the contents of flavonoid and total phenols. All these results suggested that W. anomalus has potential biocontrol efficacy to control the postharvest blue mold decay of apples

Inhibitory effects and mechanisms of vanillin on gray mold and black rot of cherry tomatoes

Vanillin is a natural antimicrobial agent; however, there are few reports on its antifungal effect on postharvest pathogenic fungi. This study aimed to investigate the in vivo and in vitro antifungal activities of vanillin against gray mold (caused by B. cinerea) and black rot (caused by A. alternata) of cherry tomato fruit and to explain its possible mechanism of action. Vanillin strongly inhibits Botrytis cinerea and Alternaria alternata mycelial growth, spore germination, and germ tube elongation in a concentration-dependent manner (P<0.05). In vivo experiments showed that 4000 mg L−1 vanillin treatment inhibited cherry tomato gray mold and black rot occurrence. Besides, intercellular electrolytes, soluble proteins, and soluble sugars leakage indicated that 50 or 100 mg L−1 vanillin treatment increased Botrytis cinerea and Alternaria alternata membrane permeability. The increase of malondialdehyde and hydrogen peroxide contents confirmed that 50 or 100 mg L−1 vanillin treatment damages the pathogen membranes. Importantly, vanillin treatment inhibited the pathogenicity-related enzyme activities of the two pathogens to reduce their infection ability, among them PL enzyme activity in A. alternata was most inhibited, reducing by 94.7 % at 6 h treated with 100 mg L-1 vanillin. The hyphae morphology of the two pathogens changed, the mycelia were severely damaged, and the hyphae surface was deformed, shrunk, or even broken after 100 mg L−1 vanillin treatment. In summary, vanillin had a substantial inhibitory effect on postharvest gray mold and black rot in cherry tomato fruit. Therefore, vanillin can be an effective alternative to prevent and control cherry tomato postharvest diseases

Effect of exogenous melatonin treatment onAspergillusdecay, aflatoxin B1 accumulation and nutritional quality of fresh “Akbari” pistachio fruit

This study aimed to investigate the mechanisms activated by melatonin treatment for attenuating Aspergillus decay, suppressing aflatoxin B1 (AB1) accumulation, and preserving nutritional quality in fresh pistachio fruits during storage at 25°C for 18 days. At 6-day intervals, samples from each of three replications were selected, and subjected to biochemical analysis. Our results showed that fresh pistachio fruits treated with 1,000 µM melatonin and inoculated with Aspergillus flavus, exhibited lower Aspergillus decay accompanied by lower endogenous AB1 accumulation. Melatonin treated fruit also showed lower H2O2 and malondialdehyde accumulation during storage. Furthermore, higher linolenic acid accumulation accompanied by higher phenols and flavonoids accumulation as well as superior DPPH scavenging capacity in fresh pistachio fruits treated with 1,000 µM melatonin, could be ascribed to lower lipoxygenase and higher phenylalanine ammonia-lyase enzymes activity, respectively, during storage. Besides, melatonin applying at 1,000 µM suppressed spore germination and germ tube elongation in A. flavus. Practical applications Aflatoxin B1 (AB1) accumulation as carcinogenic mycotoxin in pistachio fruits during Aspergillus flavus infection have been considered as a risk for human health. Since ROS generating from kernels could be responsible for triggering A. flavus growth and AB1 biosynthesis. Therefore, alleviating oxidative stress by melatonin treatment not only could be operative for attenuating fungal decay and decreasing AB1 accumulation but also could be favorable for maintaining the quality of fresh pistachio fruits.

AtENO2 functions in the development of male gametophytes in Arabidopsis thaliana

Pollen fertility is an important factor affecting the seed setting rate and seed yield of plants. The Arabidopsis thaliana enolase gene ENO2 (AtENO2) can affect the pollen morphology, germination, and pollen tube growth. AtENO2 encodes two proteins AtENO2 and AtMBP-1. To examine the effect of AtENO2 protein on pollen development, the 2nd ATG of the AtENO2 coding sequence for AtMBP-1 was mutated by site-directed mutagenesis, and transgenic plants expressing only AtENO2 but not AtMBP-1 were obtained. Phenotypic analysis indicated that AtENO2 was essential in the pollen development. The mechanisms of AtENO2 on pollen development were analyzed. AtENO2 can affect development of the pollen intine, and the mechanism may be that AtENO2 regulated the methyl esterification of pectin in pollen intine through ARF3 and AtPMEI-pi. The -734 ∼ -573 sequence of AtENO2 promoter is the main transcriptional regulatory region of AtENO2 affecting pollen development. The functional cis-acting element may be GTGANTG10(GTGA), and the trans-acting factors may be KAN, AS2 and ARF3/ETT. Moreover, the deletion of AtENO2 can cause significant difference in the expression of multiple genes related to pollen exine development. These results are useful for further studying the function of AtENO2 and exploring the mechanism of plant pollen development.

CoNPR1 and CoNPR3.1 are involved in SA- and MeSA- mediated growth of the pollen tube in Camellia oleifera.

Salicylic acid (SA) is a plant hormone involved in a series of growth, development, and stress responses in plants. Nonexpressor of pathogenesis-related genes 1 (NPR1) is the core regulatory gene in the process of SA-mediated systemic acquired resistance (SAR). Whether NPR1 is involved in pollen tube growth mediated by SA and its derivative MeSA (methyl salicylate) remains to be explored. Here, we found that the contents of endogenous SA and MeSA in self- or cross-pollinated pistils changed significantly, and exogenous SA and MeSA significantly promoted pollen germination and pollen tube elongation of Camellia oleifera at lower concentrations. CoNPR1, CoNPR3.1, CoNPR3.2, and CoNPR5 were identified, and they were all located in the nucleus. A high level of consistency was observed across the phylogenetic relationships, gene structures, and functional domains, indicating a clear division of function, as observed in other species. The expression levels of CoNPR1, CoNPR3.1, CoNPR3.2, and CoNPR5 in self- and cross-pollinated pistils had certain regularity. Furthermore, they exhibited tissue-specific expression pattern. CoNPR1 and CoNPR3.1 were expressed in pollen tubes, whose expression was regulated by SA or MeSA, and their expression patterns were basically consistent with the trend of pollen germination. These results indicate that SA and MeSA are involved in the pollen tube growth of C. oleifera, and CoNPRs may play an important role therein.

Investigating the biocontrol potentiality of Wickerhamomyces anomalus against postharvest gray mold decay in cherry tomatoes

Gray mold decay caused by Botrytis cinerea is one of the primary postharvest diseases of cherry tomatoes globally, leading to considerable economic losses. This study aimed to assess the biocontrol efficacy of Wickerhamomyces anomalus against postharvest gray mold decay in cherry tomatoes. The results indicated that W. anomalus significantly reduced the gray mold decay in cherry tomatoes in a concentration-dependent manner without affecting cherry tomatoes' quality. W. anomalus developed rapidly in wounds and on surfaces of cherry tomatoes at both 20 ± 2 °C and 4 ± 2 °C, and reduced the spore germination and germ tube length of B. cinerea in vitro. W. anomalus could adapt to the environment and compete for the nutrients and space against the pathogens. Besides, W. anomalus significantly enhanced the activities of defense-related enzymes in cherry tomatoes, including polyphenoloxidase (PPO), peroxidase (POD), catalase (CAT), and phenylalanine ammonialyase (PAL). Ultimately, the application of W. anomalus induced the disease resistance ability of cherry tomatoes. These findings suggested that W. anomalus could be a promising biocontrol agent to manage the postharvest gray mold decay in cherry tomatoes.

Solidago canadensis, a Flower or Weed?

Figure 1. Flowers or weeds? S. canadensis is one of the worst exotic weeds in China (A). Yet, farmers grow it as a cut flower (B). Because diploid cytotypes grow faster and flower earlier than other polyploids, all cultivated S. canadensis cytotypes for cut flowers are diploids. We found that diploids are sterile under hot-summer temperature south of 24°C-isotherm range and cultivation of S. canadensis will not lead to naturalization. However, the risk for naturalization increases in regions north of 20ºC-isotherm range. Photo credit: Sheng Qiang. Figure 2. Population of Solidago canadensis in native and introduced range in North America and China, respectively. S. canadensis plants are significantly taller and denser in the introduced range in China (Jiangsu) (A) than in their native range of North America (Pennsylvania, USA) (B). S. canadensis plants often outcompete native plants in invasive habitats and essentially become monoculture-type communities. Photo credit: Sheng Qiang. Figure 3. Dramatic difference in height of Solidago canadensis between native and invasive populations. S. canadensis plants can often be over 4m in height in China (Nanjing) (A), but are usually below 2m in North America (Ottawa, Canada) (B). Photo credit: Sheng Qiang. Figure 4. Field sampling site diagram. At each site, sampling plots were separated by at least 10 m to minimize the probability of sampling multiple ramets from individual genets. Photo credit: Guoqi Chen. Figure 5. Pollen germination and pollen tube growth on a stigma. (A) Pollen germination; (B) pollen tube growth; (C) penetration of pollen tubes into an ovary. Photo credit: Beibei Yao. These photographs illustrate the article “Solidago canadensis, a flower or weed?” by Sheng Qiang, Jiliang Cheng, Guoqi Chen, Beibei Yao published in Ecological Monographs. https://doi.org/10.1002/ecm.1445.

Effect of extensin-like OsPEX1 on pollen fertility in rice.

LRXs (leucine-rich repeat extensins) are chimeric cell wall proteins containing an N-terminal leucine-rich repeat (LRR) and a C-terminal extensin domain. Increasing evidences suggest that LRXs family genes play important roles in pollen germination and pollen tube growth in Arabidopsis thaliana. However, the functions of rice (Oryza sativa L.) LRX genes in pollen development remain poorly understood. Bioinformatics analysis showed that the rice LRX gene family consist of eight members, namely OsPEX3, OsLRX3 and OsLRX5 located on chromosome 1, OsLRX1, OsLRX3, OsLRX2,OsPEX1 and OsPEX2 located on chromosome 2, 5, 6, 11 and 12, respectively. The OsPEX1 gene is preferentially expressed in rice anther, suggesting that it may be involved in the regulation of pollen development. Next, we further investigated the role of the OsPEX1 gene in rice by knockdown of its expression using an RNAi approach. The OsPEX1 RNAi transgenic lines showed a significant decrease in seed setting rate (10%~30%) due to pollen sterility. Further quantitative RT-PCR analysis indicated that the OsPEX1 gene was significantly down-regulated in the RNAi transgenic lines. The results indicate that the OsPEX1plays an important role in the regulation of rice pollen development. Further studies on this gene could provide insights on the molecular and genetic mechanisms in this developmental process.

Antifungal effect of essential oil and different extracts obtained from Nepeta meyeri on Botrytis cinerea

The study concerns the antifungal effect of the aqueous and methanolic extracts, and the essential oil obtained from the aerial parts of Nepeta meyeri Benth. on Botrytis cinerea Pers. The fungus has been isolated from the infected plants of common grape Karaerik (Vitis vinifera L.) cultivating in vineyards in Üzümlü district, Erzincan (Turkey), and was cultured on potato dextrose agar medium in Petri dishes after the identification by 18S rRNA gene-based PCR assay. The concentrations of extracts from N. meyeri in Petri dishes were 2%, 5% and 10% (w/v) for aqueous extract (AE); 500, 1000 and 1500 ppm (v/v) for methanolic extract (ME), and 0.6, 0.8 and 1 µL for essential oil (EO). After the treatments, mycelial growth, spore germination, and germ tube elongation were determined. Sterile distilled water at the same ratios was used for the control treatment. Thirty-six different compounds were identified in the EO of N. meyeri by GC/MS. The highest antifungal activity has been registered for EO of N. meyeri. The inhibition rates in 1 µL/Petri of the EO were 80.72%, 18%, 38.15% on mycelial growth, spore germination and germ tube elongation, respectively. However, AE and ME of N. meyeri showed diverse effects on the studied parameters of B. cinerea. It is suggested that the favourable concentration of EO from N. meyeri can contribute to the prevention of B. cinerea infection (grey mould) which causes disease in vineyards.

Pollen tube in hazel grows intermittently: Role of Ca2+ and expression of auto-inhibited Ca2+ pump

Owing to the absence of the ovary when the female inflorescence blooms, hazel pollen tubes show an obvious intermittent growth pattern, which has an important impact on the number of fruits per cluster and yield, but little is known about the mechanisms governing this process. Spray treatments of Ca2+ and Ca2+-ATPase activator 5-aminolevulinic acid (ALA) in field experiment showed that Ca2+ treatments inhibited pistillate inflorescence drop and produced more fruits, while the effects of ALA treatments was just opposite to that of calcium treatments. Highly accumulated Ca2+ was observed at the rear part of the stigma and in the ovary primordial cell layers. Under in vitro culture conditions, pollen germination ratio and tube length were promoted and inhibited by Ca2+ and ALA, respectively. ALA treatment reduced the Ca2+ concentration in pollen tube, which was not conducive to the formation of a tip-focused Ca2+ gradient in pollen tube. The hazel genome encoded 17 Ca2+-ATPases, including 14 auto-inhibited Ca2+-ATPases and three ER-type Ca2+-ATPases. Hazel Ca2+-ATPase family proteins, including 11 common transmembrane domains, were highly conserved. Of 17 Ca2+-ATPases, qRT-PCR analysis showed that ChACA1 and ChECA2 were highly expressed in pollen tubes. In the range of 0–1.3 mM Ca2+, Ca2+ fluorescence intensity in pollen tubes, expression of ChACA1 continued to rise simultaneously, and they reached their maximum at 1.3 mM Ca2+, then declined at 1.6 mM Ca2+, which was consistent and inconsistent with changing trends of pollen tube length and ChECA2 respectively. Analysis of enzyme activity in pollen tubes showed that Ca2+-ATPase activity was promoted by both Ca2+ and ALA treatments significantly. Our findings suggested that ChACA1 may act as a key regulator of pollen germination and pollen tube development in hazel, and provide new insight into the mechanisms of unique pollen tube intermittent growth in hazel.

The Arabidopsis thaliana Class II Formin FH13 Modulates Pollen Tube Growth.

Formins are a large, evolutionarily conserved family of actin-nucleating proteins with additional roles in regulating microfilament, microtubule, and membrane dynamics. Angiosperm formins, expressed in both sporophytic and gametophytic tissues, can be divided into two subfamilies, Class I and Class II, each often exhibiting characteristic domain organization. Gametophytically expressed Class I formins have been documented to mediate plasma membrane-based actin assembly in pollen grains and pollen tubes, contributing to proper pollen germination and pollen tube tip growth, and a rice Class II formin, FH5/RMD, has been proposed to act as a positive regulator of pollen tube growth based on mutant phenotype and overexpression data. Here we report functional characterization of the Arabidopsis thaliana pollen-expressed typical Class II formin FH13 (At5g58160). Consistent with published transcriptome data, live-cell imaging in transgenic plants expressing fluorescent protein-tagged FH13 under the control of the FH13 promoter revealed expression in pollen and pollen tubes with non-homogeneous signal distribution in pollen tube cytoplasm, suggesting that this formin functions in the male gametophyte. Surprisingly, fh13 loss of function mutations do not affect plant fertility but result in stimulation of in vitro pollen tube growth, while tagged FH13 overexpression inhibits pollen tube elongation. Pollen tubes of mutants expressing a fluorescent actin marker exhibited possible minor alterations of actin organization. Our results thus indicate that FH13 controls or limits pollen tube growth, or, more generally, that typical Class II formins should be understood as modulators of pollen tube elongation rather than merely components of the molecular apparatus executing tip growth.

Antifungal properties of recombinant Puroindoline B protein against aflatoxigenic Aspergillus flavus

Aspergillus flavus contamination is of great concern to food safety. Our previous studies demonstrated that recombinant Puroindoline B protein (rPINB) has an inhibitory effect on A. flavus mycelium development. However, fungal contamination often begins with spore germination within food shelf life. Here, rPINB was evaluated for its antifungal properties against A. flavus spores in vivo and in vitro. The results showed that rPINB could inhibit spore formation and aflatoxin B1 of A. flavus on maize. In vitro analysis revealed its dose-dependent antifungal effect on spore germination and germ tube growth of A. flavus. Scanning electron microscopy revealed that rPINB exposure altered spore morphology, indicating it damaged the cell wall. Transmission electron microscopy and the inhibition of ergosterol synthesis further revealed that rPINB exposure significantly damaged the cell membrane. The mitochondrial membrane potential decreased, and DNA fragments were scattered in the cytoplasm as detected using 5,5′,6,6′-tetrachloro-1,1′,3,3′-tetraethylbenzimidazolocarbocyanine iodide and 4′,6-diamidino-2-phenylindole staining. The direct antifungal activity of rPINB observed both in vivo and in vitro suggests that rPINB may be used to prevent fungal contamination of stored foods and agricultural products in the future.

Characterization and Functional Importance of Two Glycoside Hydrolase Family 16 Genes from the Rice White Tip Nematode Aphelenchoides besseyi.

Simple SummaryThe rice white tip nematode Aphelenchoides besseyi is a plant parasite but can also feed on fungi if this alternative nutrient source is available. Glucans are a major nutrient source found in fungi, and β-linked glucans from fungi can be hydrolyzed by β-glucanases from the glycoside hydrolase family 16 (GH16). The GH16 family is abundant in A. besseyi, but their functions have not been well studied, prompting the analysis of two GH16 members (AbGH16-1 and AbGH16-2). AbGH16-1 and AbGH16-2 are most similar to GH16s from fungi and probably originated from fungi via a horizontal gene transfer event. These two genes are important for feeding on fungi: transcript levels increased when cultured with the fungus Botrytis cinerea, and the purified AbGH16-1 and AbGH16-2 proteins inhibited the growth of B. cinerea. When AbGH16-1 and AbGH16-2 expression was silenced, the reproduction ability of A. besseyi was reduced. These findings have proved for the first time that GH16s contribute to the feeding and reproduction of A. besseyi, which thus provides novel insights into how plant-parasitic nematodes can obtain nutrition from sources other than their plant hosts.The glycoside hydrolase family 16 (GH16) is widely found in prokaryotes and eukaryotes, and hydrolyzes the β-1,3(4)-linkages in polysaccharides. Notably, the rice white tip nematode Aphelenchoides besseyi harbors a higher number of GH16s compared with other plant-parasitic nematodes. In this work, two GH16 genes, namely AbGH16-1 and AbGH16-2, were isolated and characterized from A. besseyi. The deduced amino acid sequences of AbGH16-1 and AbGH16-2 contained an N-terminal signal peptide and a fungal Lam16A glucanase domain. Phylogenetic analysis revealed that AbGH16-1 and AbGH16-2 clustered with ascomycete GH16s, suggesting AbGH16-1 and AbGH16-2 were acquired by horizontal gene transfer from fungi. In situ hybridization showed that both AbGH16-1 and AbGH16-2 were specifically expressed in the nematode gonads, correlating with qPCR analysis that showed the high transcript levels of the two genes in the female nematodes. AbGH16-1 and AbGH16-2 were also significantly induced in nematodes feeding on Botrytis cinerea. Characterization of the recombinant protein showed AbGH16-1 and AbGH16-2 displayed pronounced inhibition of both conidial germination and germ tube elongation of B. cinerea. In addition, silencing of AbGH16-1 and AbGH16-2 by RNA interference significantly decreased the reproduction ability of A. besseyi and had a profound impact on the development process of offspring in this nematode. These findings have firstly proved that GH16s may play important roles in A.besseyi feeding and reproduction on fungi, which thus provides novel insights into the function of GH16s in plant-parasitic nematodes.

Biological control of early blight disease of potato caused by Alternaria alternata EBP3 by an endophytic bacterial strain Bacillus velezensis SEB1

Early blight is a well known disease causing severe loss in potato production which is used as staple food in many parts of the world. For overcoming the drawbacks of chemical fungicides used for controlling the disease, searching of suitable biocontrol agents are essential. In the present endeavour, the fungal pathogen was isolated and identified from the infected leaves of potato grown in the lateritic belt of Santiniketan, West Bengal, India. Based on morphological characteristics and sequencing of ITS region, the isolated pathogen EBP3 was identified as Alternaria alternata instead of Alternaria. solani. The pathogen was further confirmed by pathogenecity test following pot based experiment. One endophytic bacterial strain Bacillus velezensis SEB1 isolated from Vigna mungo (L.) Hepper was checked for its biocontrol efficacy against the isolated pathogen. SEB1 was found effective for inhibiting the pathogenic growth on dual culture overlay plates. In addition to fungal cell wall degrading enzymes ß-glucanase and protease, SEB1 can secrete thermostable antifungal metabolites to the extracellular broth which are insensitive to proteinase K. The crude EA fraction of the CFS of SEB1 inhibited the conidial germination and germ tube elongation of EBP3. 82.34 ± 4.56% inhibition in fungal radial growth was also observed in the presence of EA fraction at 1000 µg/ml. In vivo challenge experiments suggested decrease of disease severity form 52.47 ± 3.8% to 9.59 ± 2.1% due to application of the biocontrol agent SEB1. Based on overall observation the endophytic bacterial isolate SEB1 can be considered as a suitable biocontrol agent for controlling the early blight of potato caused by A. alternata.

Secretory Vesicles Targeted to Plasma Membrane During Pollen Germination and Tube Growth.

Pollen germination and pollen tube growth are important biological events in the sexual reproduction of higher plants, during which a large number of vesicle trafficking and membrane fusion events occur. When secretory vesicles are transported via the F-actin network in proximity to the apex of the pollen tube, the secretory vesicles are tethered and fused to the plasma membrane by tethering factors and SNARE proteins, respectively. The coupling and uncoupling between the vesicle membrane and plasma membrane are also regulated by dynamic cytoskeleton, proteins, and signaling molecules, including small G proteins, calcium, and PIP2. In this review, we focus on the current knowledge regarding secretory vesicle delivery, tethering, and fusion during pollen germination and tube growth and summarize the progress in research on how regulators and signaling molecules participate in the above processes.

RNA-Seq Highlights Molecular Events Associated With Impaired Pollen-Pistil Interactions Following Short-Term Heat Stress in Brassica napus.

The global climate change is leading to increased frequency of heatwaves with crops getting exposed to extreme temperature events. Such temperature spikes during the reproductive stage of plant development can harm crop fertility and productivity. Here we report the response of short-term heat stress events on the pollen and pistil tissues in a commercially grown cultivar of Brassica napus. Our data reveals that short-term temperature spikes not only affect pollen fitness but also impair the ability of the pistil to support pollen germination and pollen tube growth and that the heat stress sensitivity of pistil can have severe consequences for seed set and yield. Comparative transcriptome profiling of non-stressed and heat-stressed (40°C for 30 min) pollen and pistil (stigma + style) highlighted the underlying cellular mechanisms involved in heat stress response in these reproductive tissues. In pollen, cell wall organization and cellular transport-related genes possibly regulate pollen fitness under heat stress while the heat stress-induced repression of transcription factor encoding transcripts is a feature of the pistil response. Overall, high temperature altered the expression of genes involved in protein processing, regulation of transcription, pollen-pistil interactions, and misregulation of cellular organization, transport, and metabolism. Our results show that short episodes of high-temperature exposure in B. napus modulate key regulatory pathways disrupted reproductive processes, ultimately translating to yield loss. Further investigations on the genes and networks identified in the present study pave a way toward genetic improvement of the thermotolerance and reproductive performance of B. napus varieties.

Germination of Pollen Grains of Spathodia companulata P. Beauv in in vitro and in vivo like Condition with the Influence of a Promoter Medium

In vitro, germination is the most commonly used technique in pollen physiology. This provides a simple experiment method to study the pollen germination and pollen tube growth, in the endogenous as well as exogenous conditions. In vivo conditions (endogenous) can also apply to the study of pollen system. In the present investigation, the pollen germination of Spathodia companulata P. Beauv was studied in the different parts of the carpel viz., style, stigma, ovary, style-stigma, style-ovary and whole gynoecium. Spathodia companulata P. Beauv is planted for reforestation schemes, for soil conservation. In India, it is seen that there is a rare formation of fruit and seeds in this plant. Thus for the study of the growth of the plant for cultivation purposes, the growth of the pollen tube was studied which could be one of the reason for the less fruit and seed formation. Pollen tubes were found to be stimulated by those components present in the different selected parts of the carpel.

Boron Applications and Bee Pollinators Increase Strawberry Yields

ABSTRACT Several factors influence fruit set and yield in strawberry production. Bees play an important role in pollinating strawberry flowers; however, bee populations are decreasing due to air pollution and high usage of pesticides. Boron (B) can increase fruit set by improving pollen viability, germination, and pollen tube growth. This study aimed to assess how the application of honey bees and B fertilizer affects yields and marketable fruit quality of Fortuna strawberry cultivar. The experiment used two strawberry growing tunnels. One was open, thus allowing bee activity, and the other was closed, which meant that bees could not access the strawberry flowers. Each tunnel had different B applications. The presence of bees increased the total fruit yield per plant by 54% compared to the results of plants that were not pollinated by bees. Plants treated with bees yielded bigger fruit than those without bee treatment, which is likely a result of more achenes having been fertilized. Fruit formation, however, did not depend directly on pollinator activity. Both in the presence and absence of bees, applying B to the soil increased yields and decreased misshapen fruit rates. Applying B to the soil was more effective than B foliar applications. As a result of this study, it is demonstrated that strawberry plants perform at a higher rate with the application of B and the presence of bee activity.

Rizobacterias con potencial antagonista in vitro a Mycosphaerella fijiensis Morelet

El empleo de bio-controladores en la agricultura beneficia los aspectos fisiológicos en plantas, a diferencia de la constante aplicación de pesticidas en el cultivo del banano ha ocasionado la pérdida de la sensibilidad en M. fijiensis, reduciendo la microbiota del suelo. El objetivo se enfocó en caracterizar el potencial antagónico de las PGPR en inhibición de germinación de ascósporas y desarrollo micelial de M. fijiensis. Se realizaron cultivos monospóricos de M. fijiensis e identificado por PCR. Se evaluaron los extractos celulares de Pseudomonas putida PB3-6, Klebsiella variicola BO3-4, Enterobacter asburiae BA4-19, Serratia marcescens PM3-8, Enterobacter asburiae PM3-14, Pseudomonas protegens CHA0, Pseudomonas fluorescens WCS417, Pseudomonas veronii R4 y Bacillus subtilis ATCC 5540 para sus evaluaciones antagonistas: a) Inhibición del tubo germinativo de las ascósporas al 2% y b) Desarrollo micelial al (2 y 10 %). La PCR empleado en la identificación de M. fijiensis se confirma el producto de amplificación de 1018 pb. El factor antagónico de los extractos celulares al 2 % de PM3-14 y CHA0 inhibe sobre el 80 % al desarrollo de los tubos germinativos. La inhibición al desarrollo micelial del extracto celular al 2 %, de CHA0 logró una efectividad del 54 % y las cepas (PM3-8, PM3-14 y BA4-19) con (32, 26 y 26 %). Al 10 % del extracto de la cepa PM3-8 inhibe el desarrollo micelial con niveles de turbidez de 0,47 (OD600nm). El empleo de estos bio-controladores en la agricultura ofrecerá una alternativa para beneficiar en la reducción del uso de agroquímicos