Pea Fruit Research Articles

Management Of Pre And Post Harvest Fruit Rot Diseases Of Ber

The main focus of this research is to produce the good quality and disease free fruits. In this aspect, the investigation was carried out to reduce or control the pre and post-harvest fungal fruit rot. The study on pre and post-harvest management of fruit rot diseases of ber caused by Alternaria and Colletotrichum was carried out and the results showed that two pre-harvest sprays of Thiophanate Methyl (0.1 %) at 15 day intervals during the marble stage of ber fruit was found effective against Alternaria fruit rot recorded 6.8 PDI compared to untreated control recorded 43.6 PDI. Two pre-harvest sprays of 0.1 per-cent carbendazim at 15 day intervals was found effective against Colletotrichum fruit rot during the pea fruit stage of ber recorded 6.6 PDI compared to untreated control recorded 44.2 PDI. The post-harvest studies revealed that dipping of ber fruits in 2 per cent sodium chloride solution for 10 min. recorded the lowest PDI of 5.27 against post-harvest fungal rot as compared to untreated control recorded 25.27 PDI.

Sustainable Use of Traditional Plant Extracts for the Formulation of Herbal Shampoos

Skin and hair care products described with natural bioactive compounds have been considered as a better alternative to synthetic ones. Therefore, this study aimed to develop a natural shampoo using traditional plant extracts. With an emphasis on safety and efficacy, its physicochemical properties were evaluated and compared with the marketed shampoo. Each plant material was ground and extracted using 70% hydro-alcoholic solvent for 5-7 days. Shampoo formulation was prepared using sprouted fenugreek seeds extract and pea fruit extract as key ingredient along with other natural ingredients including: reetha, amla, marigold, orange peel, castor oil, glycerine and distilled water. The physicochemical parameters and antioxidant activity of both formulations were ascertained to ensure the safety and efficacy of the designed formulation. According to the present study, the developed shampoo (F1 & F2) was yellowish green and brown in color, had a good odor and optimum pH value of 5.32–5.96. The viscosity of F1 and F2 was found to be 2.3 to 2.08 poise; both formulations reduced the surface tension to 49.08 and 50.7dynes/cm respectively. While the solid content of F1 & F2 shampoos was found to be 20.57 and -21.87%. The developed shampoo (F1 & F2) exhibited significant antioxidant activity with IC 50 values of 53.46 (F1) & 69.4 µ/ml (F2), respectively. The findings of this study demonstrated that shampoo formulations were found to have functionality comparable to physicochemical features of marketed shampoo. However, further studies are necessary to validate the performance and quality of the shampoo. Keywords: herbal shampoo, shampoo formulation, traditional plant extracts. https://doi.org/10.55463/issn.1674-2974.50.4.14

Iodine biofortification of bean (Phaseolus vulgaris L.) and pea (Pisum sativum L.) plants cultivated in three different soils.

An important challenge for mankind today is to find a plant-based source of iodine, instead of table salt, which would provide the recommended daily dosage of iodine. The aim of this work was to study the accumulation of iodine and the physiochemical changes in bean (Phaseolus vulgaris L.) and pea (Pisum sativum L.) irrigated with iodine-containing water. Applying iodine at concentration of 0.5 mg L-1 resulted 51, 18, and 35% decrement in biomass of bean fruit, while in pea fruit, a 13% reduction and a 3 and 2% increment were observed when the plants were cultivated in sand, sandy silt, and silt, respectively. The highest iodine concentrations in the bean and pea fruits were detected in plants cultivated in silt soil with concentration of 0.5 mg I- L-1 and amounted to 1.6 and 0.4 mg kg-1, respectively. In presence of iodine at concentration of 0.5 mg L-1, the concentration of magnesium, phosphorous, manganese and iron increased in the bean fruit, while in the case of pea, at iodine concentration above 0.1 mg L-1 the uptake of these nutrients were hampered. Based on these facts, the iodized bean can be recommended as a possible food source to enhance the iodine intake.

Bacterioplankton Associated with Toxic Cyanobacteria Promote Pisum sativum (Pea) Growth and Nutritional Value through Positive Interactions.

Research on Plant Growth-Promoting Bacteria (PGPB) has focused much more on rhizospheric bacteria. However, PGPB associated with toxic cyanobacterial bloom (TCB) could enter the rhizosphere through irrigation water, helping plants such as Pisum sativum L. (pea) overcome oxidative stress induced by microcystin (MC) and improve plant growth and nutritional value. This study aimed to isolate bacteria associated with toxic cyanobacteria, test PGPB properties, and inoculate them as a consortium to pea seedlings irrigated with MC to investigate their role in plant protection as well as in improving growth and nutritional value. Two bacterioplankton isolates and one rhizosphere isolate were isolated and purified on a mineral salt medium supplemented with 1000 μg/L MC and identified via their 16S rRNA gene. The mixed strains were inoculated to pea seedlings in pots irrigated with 0, 50, and 100 μg/L MC. We measured the morphological and physiological parameters of pea plants at maturity and evaluated the efficiency of the plant’s enzymatic and non-enzymatic antioxidant responses to assess the role and contribution of PGPB. Both bacterioplankton isolates were identified as Starkeya sp., and the rhizobacterium was identified as Brevundimonas aurantiaca. MC addition significantly (p < 0.05) reduced all the growth parameters of the pea, i.e., total chlorophyll content, leaf quantum yield, stomatal conductance, carotenoids, and polyphenol contents, in an MC concentration-dependent manner, while bacterial presence positively affected all the measured parameters. In the MC treatment, the levels of the pea’s antioxidant traits, including SOD, CAT, POD, PPO, GST, and ascorbic acid, were increased in the sterile pots. In contrast, these levels were reduced with double and triple PGPB addition. Additionally, nutritional values such as sugars, proteins, and minerals (Ca and K) in pea fruits were reduced under MC exposure but increased with PGPB addition. Overall, in the presence of MC, PGPB seem to positively interact with pea plants and thus may constitute a natural alternative for soil fertilization when irrigated with cyanotoxin-contaminated water, increasing the yield and nutritional value of crops.

Auxins in the right space and time regulate pea fruit development.

This article comments on:Ozga JA, Jayasinghege CPA, Kaur H, Gao L, Nadeau CD, Reinecke DM. 2022 Auxin receptors as integrators of developmental and hormonal signals during reproductive development in pea. Journal of Experimental Botany 73, 4094–4112

Hormonal Influences on Pod-Seed Intercommunication during Pea Fruit Development.

Angiosperms (from the Greek “angeion”—vessel, and “sperma”—seed) are defined by the presence of specialised tissue surrounding their developing seeds. This tissue is known as the ovary and once a flower has been fertilised, it gives rise to the fruit. Fruits serve various functions in relation to the seeds they contain: they often form tough physical barriers to prevent mechanical damage, they may form specialised structures that aid in dispersal, and they act as a site of nutrient and signal exchange between the parent plant and its offspring. The close coordination of fruit growth and seed development is essential to successful reproduction. Firstly, fertilisation of the ovules is required in most angiosperm species to initiate fruit growth. Secondly, it is crucial that seed dispersal facilitated by, e.g., fruit opening or ripening occurs only once the seeds have matured. These highly coordinated events suggest that seeds and fruits are in close communication throughout development and represent a classical problem of interorgan signalling and organismic resource allocation. Here, we review the contribution of studies on the edible, unicarpellate legume Pisum sativum to our understanding of seed and fruit growth coregulation, and propose areas of new research in this species which may yield important advances for both pulse agronomy and natural science.

Higher bee abundance, but not pest abundance, in landscapes with more agriculture on a late-flowering legume crop in tropical smallholder farms.

BackgroundLandscape composition is known to affect both beneficial insect and pest communities on crop fields. Landscape composition therefore can impact ecosystem (dis)services provided by insects to crops. Though landscape effects on ecosystem service providers have been studied in large-scale agriculture in temperate regions, there is a lack of representation of tropical smallholder agriculture within this field of study, especially in sub-Sahara Africa. Legume crops can provide important food security and soil improvement benefits to vulnerable agriculturalists. However, legumes are dependent on pollinating insects, particularly bees (Hymenoptera: Apiformes) for production and are vulnerable to pests. We selected 10 pigeon pea (Fabaceae: Cajunus cajan (L.)) fields in Malawi with varying proportions of semi-natural habitat and agricultural area within a 1 km radius to study: (1) how the proportion of semi-natural habitat and agricultural area affects the abundance and richness of bees and abundance of florivorous blister beetles (Coleoptera: Melloidae), (2) if the proportion of flowers damaged and fruit set difference between open and bagged flowers are correlated with the proportion of semi-natural habitat or agricultural area and (3) if pigeon pea fruit set difference between open and bagged flowers in these landscapes was constrained by pest damage or improved by bee visitation.MethodsWe performed three, ten-minute, 15 m, transects per field to assess blister beetle abundance and bee abundance and richness. Bees were captured and identified to (morpho)species. We assessed the proportion of flowers damaged by beetles during the flowering period. We performed a pollinator and pest exclusion experiment on 15 plants per field to assess whether fruit set was pollinator limited or constrained by pests.ResultsIn our study, bee abundance was higher in areas with proportionally more agricultural area surrounding the fields. This effect was mostly driven by an increase in honeybees. Bee richness and beetle abundances were not affected by landscape characteristics, nor was flower damage or fruit set difference between bagged and open flowers. We did not observe a positive effect of bee density or richness, nor a negative effect of florivory, on fruit set difference.DiscussionIn our study area, pigeon pea flowers relatively late—well into the dry season. This could explain why we observe higher densities of bees in areas dominated by agriculture rather than in areas with more semi-natural habitat where resources for bees during this time of the year are scarce. Therefore, late flowering legumes may be an important food resource for bees during a period of scarcity in the seasonal tropics. The differences in patterns between our study and those conducted in temperate regions highlight the need for landscape-scale studies in areas outside the temperate region.

Dissipation of Pymetrozine and Penconazole On and In Pea Fruits

Estimate the residues of pymetrozine and penconazole in pea fruits were determined by using GC-ECD and HPLC-DAD with QuEChERS method. The application was carried out using knapsack sprayer equipped with one nozzle. The samples were taken after one hour, 1, 3, 5, 8, 11, 15 and 21 days of treatment. Obtained data revealed that the residual level of pymetrozine was less than the maximum residue limit (MRL= 0.02 mg/kg) which recommended by Codex Alimentation Commission, as well as penconazole (MRL= 0.05mg/kg).Data showed that penconazole residues were high persistence (t =3.6 days) than pymetrozine residues (t½=2.5 days) on pea fruits respectively. The pre-harvest interval (PHI) of pymetrozine and penconazole were 8 and 12days after treatments for pea fruits respectively. Results of household processing (washing with water, peeling and boiling) of pea fruits indicated that there are some safety methods to decrease the residues level of pymetrozine and penconazole.

TIR1 auxin receptors are implicated in the differential response to 4-Cl-IAA and IAA in developing pea fruit.

The auxins indole-3-acetic acid (IAA) and 4-chloroindole-3-acetic acid (4-Cl-IAA) occur naturally in pea (Pisum sativum); however, only 4-Cl-IAA mimics the presence of seeds in stimulating pericarp growth. To examine if this differential auxin effect is mediated through TIR1/AFB auxin receptors, pea TIR1 and AFB2 homologs were functionally characterized in Arabidopsis, and receptor expression, and auxin distribution and action were profiled in developing pea fruits. PsTIR1a, PsTIR1b, and PsAFB2 restored the auxin-sensitive root growth response to the mutant Arabidopsis seedlings Attir1-10 and/or Attir1-10 afb2-3. Expression of PsTIR1 or AtTIR1 in Attir1-10 afb2-3 mutants also restored the greater root inhibitory response of 4-Cl-IAA compared to that of IAA, implicating TIR1 receptors in this response. The ability of 4-Cl-IAA to stimulate a stronger DR5::GUS auxin response than IAA at the same concentration in pea pericarps was associated with its ability to enrich the auxin-receptor transcript pool with PsTIR1a and PsAFB2 by decreasing the transcript abundance of PsTIR1b (mimicking results in pericarps with developing seeds). Therefore, the markedly different effect of IAA and 4-Cl-IAA on pea fruit growth may at least partially involve TIR1/AFB receptors and the differential modulation of their population, resulting in specific Aux/IAA protein degradation that leads to an auxin-specific tissue response.

Quantification, dissipation behavior and risk assessment of ethion in green pea by gas chromatography-electron capture detector.

Residue investigation was carried out to scrutinize the persistence, dissipation behavior, half-life, and risk assessment of ethion on green pea fruit by spraying ethion at the fruiting stage followed by another application at 10 day intervals. The samples were extracted by using a quick, easy, low-cost, effective, rugged, and safe method, and the residues of ethion were analyzed by gas chromatography with electron capture detection. Here we report a novel, accurate, and cost-effective gas chromatography method for the determination of average deposits of ethion on green pea. The initial deposits were found to be 4.65mg/kg following the application of insecticide. Residues of ethion reached below the detection limit of 0.10mg/kg after 25 days at recommended dosage. The half-life of ethion was found to be 4.62 days. For risk assessment studies, the 25th day will be safe for consumers for the consumption of green peas. The developed method is simple, sensitive, selective, and repeatable and can be extended for ethion-based standardization of herbal formulations containing green pea and its use in pesticide industries.

Regulation of ethylene-related gene expression by indole-3-acetic acid and 4-chloroindole-3-acetic acid in relation to pea fruit and seed development.

In pea, the auxins 4-chloroindole-3-acetic acid (4-Cl-IAA) and indole-3-acetic acid (IAA) occur naturally; however, only 4-Cl-IAA stimulates pericarp growth and gibberellin (GA) biosynthesis, and inhibits the ethylene response in deseeded ovaries (pericarps), mimicking the presence of seeds. Expression of ovary ethylene biosynthesis genes was regulated similarly in most cases by the presence of 4-Cl-IAA or seeds. PsACS1 [which encodes an enzyme that synthesizes 1-aminocyclopropane-1-carboxylic acid (ACC)] transcript abundance was high in pericarp tissue adjacent to developing seeds following pollination. ACC accumulation in 4-Cl-IAA-treated deseeded pericarps was driven by high PsASC1 expression (1800-fold). 4-Cl-IAA, but not IAA, also suppressed the pericarp transcript levels of PsACS4. 4-Cl-IAA increased PsACO1 and decreased PsACO2 and PsACO3 expression (enzymes that convert ACC to ethylene) but did not change ACO enzyme activity. Increased ethylene was countered by a 4-Cl-IAA-specific decrease in ethylene responsiveness potentially via modulation of pericarp ethylene receptor and signaling gene expression. This pattern did not occur in IAA-treated pericarps. Overall, the effect of 4-Cl-IAA and IAA on ethylene biosynthesis gene expression generally explains the ethylene evolution patterns, and their effects on GA biosynthesis and ethylene signaling gene expression explain the tissue response patterns in young pea ovaries.

Differential Gene Expression in the Meristem and during Early Fruit Growth of Pisum sativum L. Identifies Potential Targets for Breeding.

For successful molecular breeding it is important to identify targets to the gene family level, and in the specific species of interest, in this case Pisum sativum L. The cytokinins have been identified as a key breeding target due to their influence on plant architecture, and on seed size and sink activity. We focused on the cytokinin biosynthetic gene family (the IPTs) and the gene family key to the destruction of cytokinins (the CKXs), as well as other gene families potentially affected by changing cytokinin levels. These included key meristem genes (WUS and BAM1) and the transporter gene families, sucrose transporters (SUTs) and amino acid permeases (AAPs). We used reverse transcription quantitative PCR (RT-qPCR) to monitor gene expression in the vegetative meristem and in pre- and post-fertilisation young pea fruits. PsWUS expression was specific to the shoot apical meristem while PsBAM1 was highly expressed in the shoot apical meristem (SAM) but was also expressed at a low level in the young fruit. Differential expression was shown between genes and within gene families for IPT, CKX, SUT, and AAP. PsCKX7 showed strong gene family member-specific expression in the SAM, and was also expressed in young pea fruits. We suggest that PsCKX7 is a potential target for downregulation via molecular breeding or gene editing.

Employing peroxidase from Thai indigenous plants for the application of hydrogen peroxide assay

Thai local plants known as banana stalk, banana blossom, banana, sugar-cane, oroxylum indicum fruit, sesbania grandiflora fruit, and pigeon pea fruit were utilized for screening peroxidase enzyme to replace costly horseradish peroxidase in the hydrogen peroxide assay. The highest peroxidase activity was found in banana stalk extracted solution. The kinetic parameters, i.e., Michaelis–Menten constant (Km) and maximum velocity (Vmax) of banana stalk peroxidase were carried out. The optimum pH and thermal stability of this enzyme were also studied. Furthermore, crude banana stalk peroxidase was applied for the determination of hydrogen peroxide in a disinfection solution without any purification. The influent parameters affecting the developed method were cautiously studied and optimized. The calibration curve of standard hydrogen peroxide was achieved between 2.0 and 10.0 μmol L−1 with correlation coefficient (r2) 0.995. The method validations of detection limit (LOD), limit of quantification (LOQ) and precision were investigated. The concentrations of hydrogen peroxide achieved by the developed method were correlated with the enzymatic method using commercial available horseradish peroxidase.

Palladium uptake by Pisum sativum: partitioning and effects on growth and reproduction.

Environmental palladium levels are increasing because of anthropogenic activities. The considerable mobility of the metal, due to solubilisation phenomena, and its known bioavailability may indicate interactions with higher organisms. The aim of the study was to determine the Pd uptake and distribution in the various organs of the higher plant Pisum sativum and the metal-induced effects on its growth and reproduction. P. sativum was grown in vermiculite with a modified Hoagland's solution of nutrients in the presence of Pd at concentrations ranging 0.10-25 mg/L. After 8-10 weeks in a controlled environment room, plants were harvested and dissected to isolate the roots, stems, leaves, pods and peas. The samples were analysed for Pd content using AAS and SEM-EDX. P. sativum absorbed Pd, supplied as K₂PdCl₄, beginning at seed germination and continuing throughout its life. Minimal doses (0.10-1.0 mg Pd/L) severely inhibited pea reproductive processes while showing a peculiar hormetic effect on root development. Pd concentrations ≥1 mg/L induced developmental delay, with late growth resumption, increased leaf biomass (up to 25%) and a 15-20% reduction of root mass. Unsuccessful repeated blossoming efforts led to misshapen pods and no seed production. Photosynthesis was also disrupted. The absorbed Pd (ca. 0.5 % of the supplied metal) was primarily fixed in the root, specifically in the cortex, reaching concentrations up to 200 μg/g. The metal moved through the stem (up to 1 μg/g) to the leaves (2 μg/g) and pods (0.3 μg/g). The presence of Pd in the pea fruits, together with established evidence of environmental Pd accumulation and bioavailability, suggests possible contamination of food plants and propagation in the food chain and must be the cause for concern.

Perfluoroalkyl acid distribution in various plant compartments of edible crops grown in biosolids-amended soils.

Crop uptake of perfluoroalkyl acids (PFAAs) from biosolids-amended soil has been identified as a potential pathway for PFAA entry into the terrestrial food chain. This study compared the uptake of PFAAs in greenhouse-grown radish (Raphanus sativus), celery (Apium graveolens var. dulce), tomato (Lycopersicon lycopersicum), and sugar snap pea (Pisum sativum var. macrocarpon) from an industrially impacted biosolids-amended soil, a municipal biosolids-amended soil, and a control soil. Individual concentrations of PFAAs, on a dry weight basis, in mature, edible portions of crops grown in soil amended with PFAA industrially impacted biosolids were highest for perfluorooctanoate (PFOA; 67 ng/g) in radish root, perfluorobutanoate (PFBA; 232 ng/g) in celery shoot, and PFBA (150 ng/g) in pea fruit. Comparatively, PFAA concentrations in edible compartments of crops grown in the municipal biosolids-amended soil and in the control soil were less than 25 ng/g. Bioaccumulation factors (BAFs) were calculated for the root, shoot, and fruit compartments (as applicable) of all crops grown in the industrially impacted soil. BAFs were highest for PFBA in the shoots of all crops, as well as in the fruit compartment of pea. Root-soil concentration factors (RCFs) for tomato and pea were independent of PFAA chain length, while radish and celery RCFs showed a slight decrease with increasing chain length. Shoot-soil concentration factors (SCFs) for all crops showed a decrease with increasing chain length (0.11 to 0.36 log decrease per CF2 group). The biggest decrease (0.54-0.58 log decrease per CF2 group) was seen in fruit-soil concentration factors (FCFs). Crop anatomy and PFAA properties were utilized to explain data trends. In general, fruit crops were found to accumulate fewer long-chain PFAAs than shoot or root crops presumably due to an increasing number of biological barriers as the contaminant is transported throughout the plant (roots to shoots to fruits). These data were incorporated into a preliminary conceptual framework for PFAA accumulation in edible crops. In addition, these data suggest that edible crops grown in soils conventionally amended for nutrients with biosolids (that are not impacted by PFAA industries) are unlikely a significant source of long-chain PFAA exposure to humans.

Evidence of 4-Cl-IAA and IAA Bound to Proteins in Pea Fruit and Seeds

The auxins 4-chloroindole-3-acetic acid (4-Cl-IAA) and indole-3-acetic acid (IAA) occur naturally in pea vegetative and fruit tissues (Pisum sativum L.). Previous work has shown that 4-Cl-IAA can substitute for the seeds in the stimulation of pea pericarp growth, whereas IAA is ineffective. Both auxins are found as free acids and as low-molecular-weight conjugates from organic solvent-soluble extracts from pea fruit. Here we present evidence for an additional conjugated auxin species that was not soluble in organic solvent and yielded 4-Cl-IAA and IAA after strong alkaline hydrolysis, suggestive of auxin attachment to pea seed and pericarp proteins. The solvent-insoluble conjugated 4-Cl-IAA in young pericarp was on average 15-fold greater than solvent-soluble 4-Cl-IAA. The solvent-insoluble conjugated IAA was approximately half the levels reported for the solvent-soluble IAA fraction. To identify putative 4-Cl-IAA-bound proteins, polyclonal antibodies were raised to 4-Cl-IAA linked to bovine serum albumin protein (BSA). Immunoblots probed with anti-4-Cl-IAA-BSA antiserum detected three to four unique bands (32–40 kDa) in primarily maternal tissues, and a different set of protein bands were detected in mainly embryonic tissues (ca. 65–74 kDa in mature seed). 4-Cl-IAA and IAA were also identified from protein fractions separated by polyacrylamide gel electrophoresis using GC-MS. These data show that the majority of 4-Cl-IAA, the growth-active auxin in young pea pericarp, and significant levels of IAA are linked to protein fractions. Auxin-proteins may function in regulation of free bioactive 4-Cl-IAA and IAA levels, and/or 4-Cl-IAA or IAA may be targeted to specific proteins post-translationally to modify protein function or stability.

Function of antioxidant enzymes and metabolites during maturation of pea fruits.

In plant cells, antioxidants keep reactive oxygen species at low concentrations, avoiding oxidative damage while allowing them to play crucial functions in signal transduction. However, little is known about the role of antioxidants during fruit maturation, especially in legumes. Snap pea (Pisum sativum) plants, which have edible fruits, were grown under nodulating and non-nodulating conditions. Fruits were classified in three maturity stages and antioxidants were determined in the seeds and seedless pods. Maturation or prolonged storage of fruits at 25 °C led to a decline in antioxidant activities and metabolites and in γ-glutamylcysteine synthetase protein. Notable exceptions were superoxide dismutase activity and glutathione peroxidase protein, which increased in one or both of these processes. During maturation, cytosolic peroxiredoxin decreased in seeds but increased in pods, and ascorbate oxidase activity was largely reduced in seeds. In stored fruits, ascorbate oxidase activity was nearly abolished in seeds but doubled in pods. It is concluded that symbiotic nitrogen fixation is as effective as nitrogen fertilization in maintaining the antioxidant capacity of pea fruits and that, contrary to climacteric fruits, a general decrease in antioxidants during maturation does not involve oxidative stress. Results underscore the importance of the antioxidant system in reproductive organs and point to ascorbate–glutathione metabolism and cytosolic peroxiredoxin as key players in pea fruit development.

The Auxins IAA and 4-Cl-IAA Differentially Modify Gibberellin Action via Ethylene Response in Developing Pea Fruit

This study explores the unique growth-regulatory roles of two naturally occurring auxins, indole-3-acetic acid (IAA) and 4-chloroindole-3-acetic acid (4-Cl-IAA), and their interactions with gibberellin (GA) during early pea (Pisum sativum L.) fruit development. We have previously shown that 4-Cl-IAA can replace the seed requirement in pea pericarp growth (length and fresh weight), whereas IAA had no effect or was inhibitory. When applied simultaneously, gibberellin (GA3 or GA1) and 4-Cl-IAA had a synergistic effect on pericarp growth. In the present study, we found that simultaneous application of IAA and GA3 to deseeded pericarps inhibited GA3-stimulated growth. The inhibitory effect of IAA on GA-stimulated growth was mimicked by treatment with ethephon (ethylene releasing agent), and the inhibitory effects of IAA and ethylene on GA-mediated growth were reversed by silver thiosulfate (STS), an ethylene action inhibitor. Although pretreatment with STS could retard senescence of IAA-treated pericarps, STS pretreatment did not lead to IAA-induced pericarp growth. Although 4-Cl-IAA stimulated growth whereas IAA was ineffective, both auxins induced similar levels of ethylene evolution. However, only 4-Cl-IAA-stimulated growth was insensitive to the effects of ethylene. Gibberellin treatment did not influence the amount of ethylene released from pericarps in the presence or absence of either auxin. We propose a growth regulatory role for 4-Cl-IAA through induction of GA biosynthesis and inhibition of ethylene action. Additionally, ethylene (IAA-induced or IAA-independent) may inhibit GA responses under physiological conditions that limit fruit growth.

Hormonal Interactions in Fruit Development

Fruit development involves a complex interplay of cell division, differentiation and expansion of sporophytic and gametophytic tissues that is carefully coordinated temporally and spatially. Plant hormones are signal molecules that regulate many processes of plant development, including fruit development leading to mature fruit and viable mature seed. Auxins, gibberellins, cytokinins, abscisic acid, and ethylene have been implicated at various stages of fruit development. In the past, hormone application studies and hormone analysis studies have supported the hypothesis that fruit development is in part regulated by hormonal interaction. More recently, biochemical, genetic, and molecular studies are beginning to unravel the complexities of how hormones affect fruit development. In the current work, we review selected studies that show the interplay between hormones during fruit development, with an emphasis on the interaction between auxin and gibberellin in pea fruit development.

Hormone and seed-specific regulation of pea fruit growth.

Growth of young pea (Pisum sativum) fruit (pericarp) requires developing seeds or, in the absence of seeds, treatment with gibberellin (GA) or auxin (4-chloroindole-3-acetic acid). This study examined the role of seeds and hormones in the regulation of cell division and elongation in early pea fruit development. Profiling histone H2A and gamma-tonoplast intrinsic protein (TIP) gene expression during early fruit development identified the relative contributions of cell division and elongation to fruit growth, whereas histological studies identified specific zones of cell division and elongation in exocarp, mesocarp, and endocarp tissues. Molecular and histological studies showed that maximal cell division was from -2 to 2 d after anthesis (DAA) and elongation from 2 to 5 DAA in pea pericarp. Maximal increase in pericarp gamma-TIP message level preceded the maximal rate of fruit growth and, in general, gamma-TIP mRNA level was useful as a qualitative marker for expanding tissue, but not as a quantitative marker for cell expansion. Seed removal resulted in rapid decreases in pericarp growth and in gamma-TIP and histone H2A message levels. In general, GA and 4-chloroindole-3-acetic acid maintained these processes in deseeded pericarp similarly to pericarps with seeds, and both hormones were required to obtain mesocarp cell sizes equivalent to intact fruit. However, GA treatment to deseeded pericarps resulted in elevated levels of gamma-TIP mRNA (6 and 7 DAA) when pericarp growth and cell enlargement were minimal. Our data support the theory that cell division and elongation are developmentally regulated during early pea fruit growth and are maintained by the hormonal interaction of GA and auxin.