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Potatoes (Solanum tuberosum L.) are one of the world's major staple crops. In stored potatoes, Pectobacterium carotovorum subsp carotovorum causes soft rot. As a result of the rapid spread of the disease during post‐harvest storage, potato production suffers huge losses. By detecting disease early and controlling it promptly, losses can be minimized. The profile of volatiles of plants can be altered by phytopathogens. Identifying unique volatile organic compounds (VOCs) as biomarkers for early disease detection has attracted considerable research attention. This study compared the VOC profiles of healthy and soft rot inoculated potatoes (cv. "Kufri Pukhraj") over a time course using gas chromatography–mass spectrometry (GC–MS). It was found that there was a differential emission of 27 VOCs between healthy non‐inoculated potatoes and soft rot inoculated potatoes. Among 27 VOCs, only five (1‐octen‐3‐ol, 2‐methylisoborneol, 3‐octanone, 1,4‐dimethyladamantane, and 2‐methyl‐2‐bornene) were found exclusively in soft rot inoculated potatoes, suggesting them potential biomarker for non‐destructive prediction of soft rot disease in potatoes. Reactive oxygen species (H2O2) and phytohormone methyl‐jasmonate (MeJa) levels increased transiently on infection with soft rot. The analysis of the primary metabolism of soft rot infected tubers at three different stages suggests metabolic reprogramming that occurs at the early stage of infection, possibly leading to biomarker volatile emission. Based on these results, it appears that the initial potato‐soft rot bacteria interaction initiates metabolic reprogramming mainly through H2O2 and the MeJa signalling pathway. In asymptomatic potatoes, these biomarkers may be promising candidates for non‐destructive detection of soft rot at an early stage. These biomarkers can be used to develop an e‐nose sensor to predict soft rot in the future. [ABSTRACT FROM AUTHOR]

Cell cultures of Asian pear (Pyrus pyrifolia) are known to produce benzoate‐derived biphenyl phytoalexins upon elicitor treatment. Although the downstream pathway for biphenyl phytoalexin biosynthesis is almost known, the upstream route of benzoic acid biosynthesis in pear has not been completely elucidated. In the present work, we report benzaldehyde synthase (BS) activity from yeast extract‐treated cell suspension cultures of P. pyrifolia. BS catalyzes the in vitro conversion of trans‐cinnamic acid to benzaldehyde using a non‐oxidative C2‐side chain cleavage mechanism. The enzyme activity was strictly dependent on the presence of a reducing agent, dithiothreitol being preferred. C2‐side chain shortening of the cinnamic acid backbone resembled the mechanisms catalyzed by 4‐hydroxybenzaldehyde synthase (HBS) activity in Vanilla planifolia and salicylaldehyde synthase (SAS) activity in tobacco and apple cell cultures. A basal BS activity was also observed in the non‐elicited cell cultures. Upon yeast extract‐treatment, a 13‐fold increase in BS activity was observed when compared to the non‐treated control cells. Moreover, feeding of the cell cultures with trans‐cinnamic acid, the substrate for BS, resulted in an enhanced level of noraucuparin, a biphenyl phytoalexin. Comparable accumulation of noraucuparin was observed upon feeding of benzaldehyde, the BS product. The preferred substrate for BS was found to be trans‐cinnamic acid, for which the apparent Km and Vmax values were 0.5 mM and 50.7 pkat mg−1 protein, respectively. Our observations indicate the contribution of BS to benzoic acid biosynthesis in Asian pear via the CoA‐independent and non‐β‐oxidative route. [ABSTRACT FROM AUTHOR]

The presence of rhamnose bound indole-3-acetic acid (IAA) was reported from acetone extract of anthers and carpels of the flowers of Peltophorum ferrugineum. Hydrolysis of the sugar ester gave IAA and rhamnose. Identification of IAA was based on physical measurements supported by bioassay. Bound and free IAA were not detected in petals, seeds and seed coats. [ABSTRACT FROM AUTHOR]

Following ion‐exchange, Sephadex LH‐20 and paper chromatography of the methanolic extracts of young, developing fruits of Aegle marmelos Correa, cytokinin‐like activity in the soybean callus assay was detected in six fractions. Of the four butanol‐soluble compounds, two were tentatively identified as zeatin and zeatin riboside, and the others as zeatin glucoside and zeatin riboside glucoside. The major cytokinino of the butanol‐insoluble fraction is probably zeatin nucleotide. The levels of compounds with cytokinin‐like activity were high during the early phase, and low in the subsequent period of fruit growth. The activity resembling that of cytokinin glucoside increased with maturation of the fruit. The content of free cytokinins in the fruits was more than that released from the tRNA. [ABSTRACT FROM AUTHOR]

The existence of cytokinins both as a free form and as a constituent of t-RNA was investigated in young fruits of Moringa pterigosperma Gaertn. Purified methanol extract was separated into butanol insoluble and butanol soluble fractions. The cytokinin(s) in the butanol insoluble fraction was tentatively identified as zeatin nucleotide. The butanol soluble fraction contained. cytokinins and was chromatographed on Sephadex LH-20 with 35% ethanol. The two active fractions from LH-20 column coincided with zeatin and zeatin riboside. Cytokinin per g tissue was high in early stages of fruit growth and then remained more or less constant. Alkaline phosphatase hydrolysis of t-RNA hydrolysate of fruit tissue showed considerable cytokinin activity. [ABSTRACT FROM AUTHOR]

The present experiment provides information on the phosphorus compounds in rice seeds and elucidates the changes they undergo during germination. In ungerminated seeds, the bulk of total-P appears in phytin (about 76 per cent). It is then dephosphorylated in course of germination with a simultaneous accumulation of large amounts of inorganic-P. Lipid-P increases very rapidly from 0 to 24 hours. The increase up to 72 hours is gradual, after which it drops at 96 hours and again rises to a maximum after 120 hours. The ester-P and RNA-P fractions increase in concentration with time of germination (except 120 hours) Protein-P begins to fall afar 48 hours, while DNA P remains more or less constant throughout the experiment. The two pH optima recorded for phytase activity at 4.0 and 9.0, suggest that there exist two phytases, one acidic and the other alkaline. Both behave similarly during germination with a continuous increase throughout the course of the course of the experiment. The enzyme with an optimal pH at 4 hydrolyses phytin more actively than the other with the pH optimum at 9.0. Phytase shows maximum activity at a stage when most of the phytin has disappeared; the metabolic significance is uncertain. [ABSTRACT FROM AUTHOR]

Metabolic changes in developing rice seeds were studied with respect to respiration, carbohydrate and nitrogen fractions, nucleic acids and hydrolytic enzymes, viz. α-amylase, adenosine triphosphatase (ATPase) and phytase. -- Respiration rate was maximum after 12 days from the date of pollination and became feeble afterwards with the fall in the moisture content of the maturing seeds. In the early stage, there was a preponderance of reducing sugars which were replaced later by nonreducing forms. Dry matter accumulation was mainly due to the steady rise in starch content. There was a gradual accumulation of protein nitrogen throughout the experiment, the rate being highest between 12-16 days. RNA content increased steadily till the seeds became mature, while DNA formed rapidly during the first 20 days and was maintained at the same level thereafter. -- α-Amylase activity increased up to 20 days and declined sharply afterwards. The peak activities of ATPase and phytase were recorded at 32 and 24 days after pollination, respectively.

Experiments were carried out with viable and nonviable rice seeds to detect the nature of germination inhibitors. An abscisic acid like factor is present in nonviable seeds but absent in viable ones. The main source of the factor is the embryo although measurable amounts are also obtained from the husk; it is not found in the endosperm however. Interaction with GA3 and IAA suggests that both the rice seed inhibitor and abscisic acid are antagonistic to GA3 and partially reversed the IAA induced growth. The similarity of the UV absorption spectra of the inhibitor and abscisic acid also proves its presence in nonviable seeds. The inhibitor suppresses the α-amylase activity both in intact and excised seeds in the same way as abscisic acid but the suppression is partially overcome with higher concentrations of GA3. [ABSTRACT FROM AUTHOR]

Relative distribution of bound and free forms of nicotine acid in rice and wheat seeds and their metabolism during germination were the subject of the present investigation. Measurement of the levels of NAD (nicotinamide adenine dinucleotide) and NADP (nicotinamide adenine dinucleotide phosphate) formed another part of the work. Total nicotinic acid in both rice and wheat increased with germination and was maximum at 72 hours. From this time onwards, it began to decline rapidly and at the end of experiment, i.e., after 120 hours, it was lower than that for ungerminated seeds on per seedling basis, although it was slightly higher on per g dry weight basis. Ungerminated seeds of wheat and rice contained about 89 per cent and 80 per cent respectively of their total nicotinic acid in bound form which became partially free in course of germination. Total nucleotides (oxidised plus reduced forms) increased progressively up to 96 hours followed by a slight fall at 120 hours. NAD reached a maximum at 24 hours and fell gradually thereafter. The depletion of NAD was associated with a progressive accumulation of NADH. NADP decreased from the peak value at 72 hours. Formation of NADP and its maintenance at high level depend on NAD in the oxidized form and the content slowed down in tissues with higher NADH/NAD ratio. A relatively large amount of NADPH was present throughout the experiment. [ABSTRACT FROM AUTHOR]

The growth substances of the seeds of Cassia fistula were studied and the changes in the relative levels in the endosperm and embryo (plus cotyledons) with development of the seed were noted. Indoleacetic acid was found lo he the major auxin component of the seed almost throughout its growth and development, while acidic inhibitors possibly belonging to β-complex were also noted in bioassay tests. The main source of the IAA in the seed is the endosperm, although measurable amounts are also present in the embryo. While this IAA activity in the endosperm is detectable till maturity of the fruit, it decreases relatively in the embryo lo fall to insignificance at maturity of the seed. However, there is indication of the binding of such IAA in the embryo or the cotyledon, which can be released by alkaline hydrolysis but not before the seeds are matured. No such bound auxin could be detected in the endosperm. The inhibitors, on the other band. are more prominent in the embryo than in the endosperm, particularly with ageing of the fruit. The possible significance of these changes in the growth factors has been discussed in relation to the age of the seed and the development of the embryo inside it. [ABSTRACT FROM AUTHOR]

Paper chromatographic determination of amino acids separately from the embryo and endosperm of rice (Oryza sativa L.) during germination and seedling growth without added nutrients for 8 days has been made. After different hours of germination the endospermic protein is hydrolysed and other amino acids appear and are translocated to the embryo. Arginine, tryptophane, tyrosine and ornithine are detected in the embryo during its growth but absent in the endosperm. Their appearance in the embryo is suggestive of interconversion by transamination. [ABSTRACT FROM AUTHOR]

Experiments to demonstrate the presence of growth regulating properties of the root extract of water hyacinth (Eichhornia speciosa Kunth) have been performed. The aqueous extract in cold was found to have accelerated shoot growth of several varieties of rice, oat, wheat, maize, Cicer, Arachis, and mustard: and inhibited root growth. A comparison of the effects of extract with those of IAA or GA indicates that the growth manifestations are not identical suggesting a different type of substance or substances present in the root of water hyacinth. [ABSTRACT FROM AUTHOR]