Effect of Rhizobium–Azospirillum coinoculation on nitrogen fixation and yield of two contrasting Phaseolus vulgaris L. genotypes cultivated across different environments in Cuba

Azospirillum spp. have shown potential to enhance nodulation and plant growth of legumes when coinoculated with Rhizobium. The effect of Azospirillum on the Rhizobium-legume symbiosis is, however, dependent on the host genotype used. Previous greenhouse experiments identified two genotypes of common bean (Phaseolus vulgaris L.), BAT477 and DOR364, contrasting in nodulation response to Azospirillum when coinoculated with Rhizobium. Genetic analysis revealed a genetic basis (Quantitative Trait Loci) on the bean genome related to the differential responsiveness to Azospirillum between the two bean genotypes. In this study, on-station and on-farm field experiments in different regions in Cuba were conducted to evaluate the agronomic relevance of the differences in response to Azospirillum–Rhizobium coinoculation between the two genotypes BAT477 and DOR364. It was observed that Azospirillum–Rhizobium coinoculation as compared to single Rhizobium inoculation increased the amount of fixed nitrogen and the yield of DOR364 across all sites. For BAT477, on the contrary, a negative effect of Azospirillum–Rhizobium coinoculation on yield and nitrogen fixation was observed on most of the sites as compared to single Rhizobium inoculation. The modified stability regression equations resulting from this study may contribute to predict how a combination of genotype and inoculum will perform at a certain environmental setting. This study highlights the importance of genotype × inocula interactions in agricultural outputs and establishes a link between greenhouse phenotype, genetic background and performance in the field.     

Temporal and Hormonal Control of β-1,3-Glucanase in Phaseolus vulgaris L

The endo-beta-1, 3-glucanase (beta-1, 3-glucan 3-glucanhydrolase, EC 3.2.1.6) extracted from Phaseolus vulgaris L. cv. Red Kidney had a pH optimum of 5 and a temperature optimum of 50 C. Excision of plant tissue resulted in an increase in beta-1, 3-glucanase activity after a 6-hour lag period. The increase could be prevented by indole-3-acetic acid, gibberellic acid, and cytokinins. Ethylene (half-maximal concentration = 0.1 microliter/liter) promoted the synthesis of beta-1, 3-glucanase, and 10% CO(2) overcame some of the ethylene effect. Cycloheximide prevented the induction of beta-1, 3-glucanase, but actinomycin D and chromomycin A(3) had only a partial effect.The amount of callose in sieve tube cells correlated with levels of beta-1, 3-glucanase, suggesting that this enzyme played a role in the degradation of beta-1, 3-glucans.     

Effects of Long-Term Exposure to Low-Power 915 MHz Unmodulated Radiation on Phaseolus vulgaris L.

The morphophysiological response of Phaseolus vulgaris L. to low-power electromagnetic radiation was investigated in order to assess the potential harmful effects of long-term continuous exposure. The plants were grown in two separate electromagnetic field (EMF) shielded rooms, in a controlled, greenhouse-like environment. One batch was continuously irradiated during the growth period (from sowing to maturity) and the other one was used as a reference. An unmodulated signal at 915 MHz (the central frequency between the uplink and downlink of the GSM900 mobile communications band) was used, with a maximum power density of 10 mW/m² measured near the plants. The plants were analyzed using ultraviolet–visible, statistical, morphometric, and electron microscopy methods. Significant differences were observed regarding the height of the plants, number of inflorescences, and chlorophyll and carotenoid content, all closely connected with the ultrastructural changes observed in the leaves. The irradiated batch grew higher (19% increase in plant height, 20% increase in stem and leaves' dry mass), with 18% fewer inflorescences, and extremely long roots (34% increase in dry mass). The ultrastructure of the irradiated leaves showed irregular cells and a higher content of plastoglobules in the chloroplasts. All results indicate that the irradiated plants suffered significant morphological modifications during their long-term exposure to the specific EM radiation. Bioelectromagnetics. © 2020 Bioelectromagnetics Society     

Effect of chitosan on tobacco mosaic virus（TMV） accumulation,hydrolase activity,and morphological abnormalities of the viral particles in leaves of N. tabacum L. cv. Samsun

The effect of chitosan on the development of infection caused by Tobacco mosaic virus（TMV） in leaves of Nicotiana tabacum L. cv. Samsun has been studied. It was shown that the infectivity and viral coat protein content in leaves inoculated with a mixture of TMV（2 μg/mL） and chitosan（1 mg/mL） were lower in the early period of infection（3 days after inoculation）, by 63% and 66% respectively, than in leaves inoculated with TMV only. Treatment of leaves with chitosan 24 h before inoculation with TMV also caused the antiviral effects, but these were less apparent than when the virus and polysaccharide were applied simultaneously. The inhibitory effects of the agent decreased as the infection progressed. Inoculation of leaves with TMV together with chitosan considerably enhanced the activity of hydrolases（proteases, RNases） in the leaves, in comparison with leaves inoculated with TMV alone. Electron microscope assays of phosphotungstic acid（PTA）-stained suspensions from infected tobacco leaves showed that, in addition to the normal TMV particles（18 nm in diameter, 300 nm long）, these suspensions contained abnormal（swollen, “thin” and “short”） virions. The highest number of abnormal virions was found in suspensions from leaves inoculated with a mixture of TMV and chitosan. Immuno-electron microscopy showed that “thin” virus particles, in contrast to the particles of normal diameter, lost the ability to bind to specific antiserum. It seems that the chitosan-induced activation of hydrolases stimulates the intracellular degradation of TMV particles and hence hydrolase activation may be considered to be one of the polysaccharide-mediated cellular defense mechanisms that limit virus accumulation in cells.     

Immuno-localization of Calmodulin in Unfertilized and Fertilized Embryo Sacs in Nicotiana tabacum var.macrophylla

Light microscopic immunohistochemical techniques with horse radish peroxidase(HRP)-conjugated second antibody and protein A-gold immunoelectron microscopic techniques were used to study the distribution of calmodulin (CaM) in unfertilized and fertilized embryo sacs in Nicotiana tabacum var. mocrophylla. Before fertilization, CaM was richer in the egg apparatus cells and antipodal cells than in the central cell. During the course from pollination to fertilization, the persistent synergid contained more CaM than the degenerated synergid. Meanwhile, two distinct bands rich in CaM were observed between the egg apparatus and the central cell, and gradually fused with each other appearing arc shape. When the two polar nuclei had fused, this CaM-rich band began to disappear. After fertilization, CaM level was still high in the zygote and the persistent synergid but low in the endosperm cells. Although there was no evidence about the polar distribution of CaM in the zygote, distinguishable difference, however, existed between the apical cell and the basal cell of a proembryo, being higher in the former than in the latter. The function of CaM during double fertilization and early embryogenesis as well as the temopral relationship between the CaM-rich band and the actin corona reported by other investigators are discussed.     

Studies on synthetic hybrids of british species of Senecio: I Senecio viscosus L. × S. vulgaris L.

Summary

Four aquatic hyphomycetes and one terrestrial fungus were examined for their responses to the phenoxy herbicides (±)-MCPP and 2,4-D as both single and binary preparations with respect to hyphal extension, sporulation and respiration. Hyphal extension of all species was unaffected at concentrations less than 100 mg l^?1. At higher concentrations there was a variable inhibitory response to the herbicides but no clear pattern was observed between the five fungi. The binary herbicide mixture had a weak synergistic effect on inhibition of growth rate. For the four aquatic hyphomycetes sporulation was reduced at several herbicide concentrations, but there was no consistent reduction over the experimental period. Flagellospora curvula and Clavariopsis aquatica showed increased sporulation at 100 and 1000 mg l^?1 for only some herbicide combinations. The respiration rates of the fungi varied with species and herbicide concentration and ranged between stimulation at 100 mg l^?1 to inhibition at 4000 mg l^?1. The results indicate that the five fungi are not likely to be severely effected by the phenoxy herbicides at concentrations normally occurring in the field. The possible effects of these herbicides on nutrient cycling are briefly discussed.     

Apoptotic cell death induces temperature-sensitive lethality in hybrid seedlings and calli derived from the cross of Nicotiana suaveolens×N. tabacum

Hybrid lethality expressed in the interspecific hybrid of Nicotiana suaveolens Lehm. ×N. tabacum L. cv. Hicks-2 is one of the mechanisms for reproductive isolation and it is temperature-sensitive. Apoptotic changes were detected in the cells of hybrid seedlings and calli expressing lethality at 28 °C but not under high-temperature conditions (36 °C), when the lethality is suppressed. Condensation of chromatin, fragmentation of nuclei and cytoplasmic reduction are the cytological changes associated with apoptosis leading to hybrid lethality. Fragmentation of nuclei was correlated with the lethal symptoms in both hybrid seedlings and calli, as confirmed by fluorimetry of the nuclear DNA using laser scanning cytometry. Agarose gel analysis of DNA extracted from hybrid seedlings and calli showing lethal symptoms revealed a specific ladder pattern suggesting nucleosomal fragmentation which is one of the biochemical changes of apoptosis. In-situ detection using terminal deoxyribonucleotidyl transferase-mediated dUTP-fluorescein nick end labeling (TUNEL) showed that this process occurred in distinct stages on each organ of hybrid seedlings and centripetally in hybrid calli. From these results, we confirmed that cell death inducing hybrid lethality was indeed apoptosis. Received: 23 December 1999 / Accepted: 5 April 2000     

Effects of drought stress on the evergreen Quercus ilex L., the deciduous Q. robur L. and their hybrid Q. × turneri Willd.

Five-year-old trees of deciduous Quercus robur L., evergreen Q. ilex L., and their semideciduous hybrid, Q. × turneri Willd. (var. pseudoturneri), growing in pots, were subjected to drought stress by withholding water for 18–22 days, until leaf water potentials decreased below ?2 MPa. Gas-exchange rates, oxygen evolution, and modulated chlorophyll (Chl) fluorescence measurements revealed that by strong stomata closure and declining photosynthetic capacity down to approximately 50%, all three taxa responded with strongly reduced photosynthesis rates. In Q. robur, photochemical quenching of the drought-stressed plants was much lower than in nonstressed controls. Dissection of the occurring events in the photosynthetic electron transport chain by fast Chl fluorescence induction analysis with the JIP-test were discussed.     

Genetic analysis of single-locus and epistatic QTLs for seed traits in an adapted × nuña RIL population of common bean (Phaseolus vulgaris L.)

Key message

The QTLs analyses here reported demonstrate the significant role of both individual additive and epistatic effects in the genetic control of seed quality traits in the Andean common bean.

Abstract

Common bean shows considerable variability in seed size and coat color, which are important agronomic traits determining farmer and consumer acceptability. Therefore, strategies must be devised to improve the genetic base of cultivated germplasm with new alleles that would contribute positively to breeding programs. For that purpose, a population of 185 recombinant inbred lines derived from an Andean intra-gene pool cross, involving an adapted common bean (PMB0225 parent) and an exotic nuña bean (PHA1037 parent), was evaluated under six different—short and long-day—environmental conditions for seed dimension, weight, color, and brightness traits, as well as the number of seed per pod. A multi-environment Quantitative Trait Loci (QTL) analysis was carried out and 59 QTLs were mapped on all linkage groups, 18 of which had only individual additive effects, while 27 showed only epistatic effects and 14 had both individual additive and epistatic effects. Multivariate models that included significant QTL explained from 8 to 68  % and 2 to 15 % of the additive and epistatic effects, respectively. Most of these QTLs were consistent over environment, though interactions between QTLs and environments were also detected. Despite this, QTLs with differential effect on long-day and short-day environments were not found. QTLs identified were positioned in cluster, suggesting that either pleiotropic QTLs control several traits or tightly linked QTLs for different traits map together in the same genomic regions. Overall, our results show that digenic epistatic interactions clearly play an important role in the genetic control of seed quality traits in the Andean common bean.     

Computational analysis of common bean (Phaseolus vulgaris L., genotype BAT93) lycopene β-cyclase and β-carotene hydroxylase gene's cDNA

The identification of genes and understanding of genes'' expression and regulation in common bean (Phaseolus vulgaris L.) is necessary in order to strategize its improvement using genetic engineering techniques. Generation of expressed sequence tags (ESTs) is useful in rapid isolation, identification and characterization of the genes. To study the gene expression in P. vulgaris pods tissue, ESTs generation work was initiated. Early stage and late stage bean-pod-tissues cDNA libraries were constructed using CloneMiner cDNA library construction kit. In total, 5972 EST clones were isolated using random method of gene isolation. While processing ESTs, we found lycopene β-cyclase (PvLCY-β) and β-carotene hydroxylase (PvCHY-β) gene''s cDNA. In carotenoid biosynthesis pathway, PvLCY-β catalyzes the production of carotene; and PvCHY-β is known to function as a catalyst in the production of lutein and zeaxanthin. To understand more about PvLCY-β and PvCHY-β, both strands of both cDNA clones were sequenced using M13 forward and reverse primers. Nucleotide and deduced protein sequences were analyzed and annotated using online bioinformatics tools. Results showed that PvLCY-β and PvCHY-β cDNAs are 1639 and 1107 bp in length, respectively. Analysis results showed that PvLCY-β and PvCHY-β gene''s cDNA contains an open reading frame (ORF) that encodes for 502 and 305 amino acid residues, respectively. The deduced protein sequence analysis results also showed the presence of conserved domains needed for PvLCY-β and PvCHY-β functions. The phylogenetic analysis of both PvLCY-β and PvCHY-β proteins showed it''s closeness with the LCY-β and CHY-β proteins from Glycine max, respectively. The nucleotide sequence of PvLCY-β and PvCHY-β gene''s cDNA and it''s annotation is reported in this paper.     

Effect of picloram and methyl jasmonate on growth and taxane accumulation in callus culture of Taxus × media var. Hatfieldii

We have analysed the effect of some culture conditions and media components on callus growth rate and production of taxanes in callus of Taxus × media var. Hatfieldii. For callus induction and maintenance a Gamborg B5 medium and a White - Rangaswamy medium (WR) with different modifications were used. On an improved WR medium (containing 10 μM picloram) the callus growth factor increased up to 5.8 fold (fresh weight). Picloram only enhanced the growth of callus, but not taxane production. On WR medium with (100 μM) methyl jasmonate the paclitaxel content increased from 2.37 μg g-1 to 90 μg g-1 and cephalomannine from 5.14 μg g-1 to 29.14 μg g-1 (dry weight), whereas growth of the cultures ceased. The presence of paclitaxel and cephalomannine was established by high performance liquid chromatography. This revised version was published online in June 2006 with corrections to the Cover Date.     

Regulation of adenosine 5′-phosphosulfate sulfotransferase activity by H2S and cyst(e)ine in primary leaves of Phaseolus vulgaris L.

During chloroplast development in the primary leaves of Phaseolus vulgaris, the extractable activity of adenosine 5-phosphosulfate sulfotransferase increased ten-fold. When chloroplast development took place in air enriched with 3.5 l H₂S·l^-1 there was a decrease in adenosine 5-phosphosulfate sulfotransferase activity. Cyst(e)ine in concentrations up to 1 mM (in the external medium) did not affect the increase in adenosine 5-phosphosulfate sulfotransferase activity in intact plants. In plants with excised roots, 0.75 mM cyst(e)ine inhibited this increase. In green primary leaves, H₂S or cyst(e)ine treatment resulted in a decrease of extractable adenosine 5-phosphosulfate sulfotransferase activity. In intact plants, this effect of cyst(e)ine was observed at a concentration of 1 mM, and in plants with excised roots, 0.25 mM had a comparable effect.In developing plants, the extractable activities of O-acetyl-L-serine sulfhydrylase (EC 4.2.99.9) and ribulosebisphosphate carboxylase (EC 4.1.1.39.) were not affected by H₂S or cyst(e)ine.Abbreviations APS adenosine 5-phosphosulfate - APSSTase adenosine 5phosphosulfate sulfotransferase - BSA bovine serum albumin - DTE dithioerythritol - EDTA ethylenediaminetetra-acetic acid - OASSase O-acetyl-L-serine sulfhydrylase - PAPS adenosine 3-phosphate 5-phosphosulfate - POPOP 1,4 Di 2-(5-phenyloxazolyl)-benzene - PPO 2,5-diphenyloxazol - RubP ribulose-bisphosphate - RubPCase ribulosebiphosphate carboxylase This is no. 8 in the series Regulation of Sulfate Assimilation in Plants. The term cysteine is used when it is clear that cystine is not involved; cyst(e)ine is used for an undefined mixture of cysteine and cystine. The concentrations are expressed in all cases relative to cysteine     

Seed structure in Crocus sativus L. ×, C. cartwrightianus Herb., C. thomasii Ten., and C. hadriaticus Herb. at SEM

Crocus sativus L. (Iridaceae) is a sterile triploid geophyte widely cultivated for the production of the spice saffron and only reproduced by means of corms. Extensive research has identified Crocus cartwrightianus Herb. as being a probable progenitor of C. sativus. However, other diploid Crocus species of the same C. sativus group, such as C. thomasii Ten. and C. hadriaticus Herb., have been considered as possible progenitors of saffron. Of the characteristics for distinguishing critical genera, species and intraspecific taxa of angiosperms, the most widely adopted have been seed organisation and patterns of spermoderma microstructure detected at SEM. The aim of this study is to use SEM to analyse the seeds of C. sativus ×, a cross obtained by C. sativus with pollen of C. cartwrightianus Herb. and the seeds of allopollinated C. cartwrightianus, C. thomasii Ten., and C. hadriaticus Herb. Results indicate that the seed surface microstructure of C. sativus × is very similar to that of C. cartwrightianus while being different from those of C. thomasii and C. hadriaticus.