Temporal variability and scaling behaviour in the fine-root system of kiwifruit (Actinidia deliciosa)

We show that temporal variability in root populations can depend upon the scale of measurement (particularly the sampled soil volume). The presence of roots in a range of volumes of soil was studied using perspex tubes installed horizontally into the soil around three mature kiwifruit vines. Roots intercepting lines scored on the tubes were counted using a periscope. For small volumes of soil (c. 2–4 cm³) the root counts varied with time in a very irregular manner, and as the interval between measurements increased the autocorrelation between the measurements decayed rapidly. At about half of the locations monitored there was no significant autocorrelation between measurements 27 d apart. Linear interpolation in these time series was unreliable, and where the correlation dimension could be resolved it was usually non-integer (suggesting chaotic behaviour). The time series measured at different locations were poorly correlated, indicating weak coordination. As the observed soil volume increased, the coordination between locations improved, the autocorrelation function increased, and linear interpolation errors decreased (although these remained substantial). Clearly there are considerable fundamental constraints on our ability to predict the root behaviour of kiwifruit vines at scales that are appropriate for mechanistic models of nutrient and water uptake. We discuss the need for a new conceptual model of the fine-root systems of kiwifruit and similar species.     

Cytokinins and fruit development in the kiwifruit (Actinidia deliciosa). II. Effects of reduced pollination and CPPU application

The significance of changes in cytokinin content during early fruit growth was examined in the kiwifruit ( Actinidia deliciosa var. deliciosa cv. Hayward). Fruit growth was modified by the reduction of seed number or by the application of the synthetic phenylurea cytokinin N -(2-chloro-4-pyridyl)- N -phenylurea (CPPU). The influence of these treatments on cell division was monitored by flow cytometry and changes in the endogenous cytokinins were measured at days 10 and 20 after anthesis, using high-performance liquid chromatography and radioimmunoassay. Total cytokinin levels appeared not to be limiting growth since the highest total cytokinin concentration was detected in unpollinated fruit, which abscised by day 25 after anthesis. However, compared with control fruit which had the highest concentration of zeatin (Z) 10 days post anthesis, Z levels were low in unpollinated fruit. It is hypothesised that an increase in Z is the critical change in cytokinin metabolism required for the initiation of cell division and fruit growth. The synthetic cytokinin CPPU promoted fruit development, but there was a decrease in the endogenous cytokinin concentration. Zeatin was not detected in CPPU-treated fruit. Cell division was reduced in unpollinated fruitlets but there was no significant difference ( P > 0.05) between the other treatments. Differences in final fruit size appeared to be due to cell expansion.     

Multiple roles of proline in plant stress tolerance and development

The recent progresses in the research on proline will be described, focusing on plants and covering proline metabolism and signal transduction as well as the role of this imino acid in stress response. Furthermore, the recently described developmental role of proline in flowering and reproduction will be illustrated and discussed.      

Differential responses of the enzymes involved in proline biosynthesis and degradation in drought tolerant and sensitive cotton genotypes during drought stress and recovery

The relative water content (RWC), free proline levels and the activities of enzymes involved in proline metabolism were studied in drought tolerant (Ca/H 680) and drought sensitive (Ca/H 148) genotypes of cotton (Gossypium hirsutum L.) during induction of water stress and posterior recovery. Water stress caused a significant increase in proline levels and P5CS activity in leaves of both tolerant and sensitive genotypes, whereas the activity of P5CR increased minimally and the activity of OAT remains unchanged. The activity of PDH decreased under drought stress in both the genotypes. The leaf of tolerant genotype maintained higher RWC, photosynthetic activity and proline levels, as well as higher P5CS and P5CR activities under water stress than that of drought sensitive genotype. The drought induced proline levels and activities of P5CS and P5CR declined and tend to be equal to their respective controls, during recovery, whereas the PDH activity tends to increase. These results indicate that induction of proline levels by up regulation of P5CS and down regulation of PDH may be involved in the development of drought tolerance in cotton.     

Comparison of bacterial and plant genes participating in proline biosynthesis with Osmotin gene, with respect to enhancing salinity tolerance of transgenic tobacco plants

In an attempt to increase tolerance to salinity stress in tobacco plants, the genes encoding the mutant form of glutamyl kinase (proB), pyrroline-5-carboxylate synthetase, and osmotin were cloned into three different shuttle vectors and were separately introduced into the tobacco plants. The transgenic lines were compared for their ability to produce shoots and grow in MS medium containing 320 mM NaCl; it was shown that the transgenic lines containing genetically handled osmotin gene are more resistant to salinity. The amount of chlorophyll a was used to show continuing growth of plant lines. The results showed that only the tobacco lines transformed with the modified osmotin gene exhibited greater tolerance to salinity. Published in Russian in Fiziologiya Rastenii, 2006, Vol. 53, No. 1, pp. 122–127. The text was submitted by the authors in English.     

The effect of NaCl on proline accumulation in potato seedlings and calli

The effects of salt stress were studied on the accumulation and metabolism of proline and its correlation with Na⁺ and K⁺ content in shoots and callus tissue of four potato cultivars, viz., Agria, Kennebec (relatively salt tolerant), Diamant and Ajax (relatively salt sensitive). Na⁺ and proline contents increased in all cultivars under salt stress. However, K⁺ and protein contents decreased in response to NaCl treatments. The activities of enzymes involved in proline metabolism, Δ¹-pyrroline-5-carboxylate synthetase (P5CS) and proline dehydrogenase (ProDH) increased and decreased, respectively, in response to elevated NaCl concentrations. The changes of P5CS and ProDH activities in more salt sensitive cultivars (Diamant, Ajax) were more than those in the tolerant ones. Then the stimulation of synthesis in combination with a partially increase of protein proteolysis, a decrease in proline utilization and inhibition of oxidation resulted in high proline contents in seedlings and calli under salt stress. In callus tissue, reduced growth and cell size may be partially responsible for high proline accumulation in response to high NaCl levels. However, although the basic proline contents in the seedlings of more salt tolerant cultivars were higher than the sensitive ones, a clear relationship was not generally observed between accumulation of proline and salt tolerance in potato.     

Isolation and expression analysis of proline metabolism-related genes in Chrysanthemum lavandulifolium

Proline plays a significant role in plant resistance to abiotic stresses, and its level is determined by a combination of synthesis, catabolism and transport. The primary proteins involved are Δ¹-pyrroline-5-carboxylate synthetase (P5CS), proline dehydrogenase (PDH) and proline transporter (ProT). To utilise proline metabolism to improve the stress resistance of Chrysanthemum × morifolium, we isolated two P5CS-homologous genes (ClP5CS1 and ClP5CS2), one PDH gene (ClPDH) and four ProT-homologous genes (ClProT1-4) (GenBANK accession numbers: KF743136–KF743142) from Chrysanthemum lavandulifolium, which is closely related to chrysanthemums and exhibits strong resistance to stresses. Expression analysis of these genes in different organs and under various stresses indicated that ClP5CSs showed substantial constitutive expression, while ClPDH was only strongly expressed in the capitulum and was inhibited under most stresses. The expression patterns of four ClProT genes presented characteristics of organ specificity and disparity under stresses. Above all, the expression of ClProT2 was restricted to above-ground organs, especially strong in the capitulum and could be obviously induced by various stress conditions. Promoters of ClPDH and ClProTs contained many cis-acting regulatory elements involved in stress responses and plant growth and development. High levels of free proline were found in flower buds, the capitulum under the non-stress condition and later periods of stress conditions except cold treatment. Interestingly, organ specificity and disparity also exist in the level of free proline under different stress conditions. Our study indicates that ClProTs play significant roles in proline accumulation and stress responses, and that ClProT2 could be used to genetically modify the stress resistance of chrysanthemums. In addition, proline metabolism might be closely related to plant flowering and floral development.     

Effects of Juglone on Growth of Muskmelon Seedlings with Respect to Physiological and Anatomical Parameters

The effect phosphinothricin (PPT), an inhibitor of glutamine synthetase (GS), on proline accumulation in detached rice leaves was investigated. During 12 h incubation, PPT inhibited GS activity and induced accumulation of NH₄ ⁺, and accumulation of proline in the light but not in darkness. Proline accumulation caused by PPT in the light was related to protein hydrolysis, and increase in the contents of precursors of proline, ornithine and arginine. Abscisic acid accumulation was not required for proline accumulation in PPT-treated rice leaves. This revised version was published online in July 2006 with corrections to the Cover Date.     

Cloning and expression analysis of ten genes associated with picrosides biosynthesis in Picrorhiza kurrooa

Picrorhiza kurrooa Royle ex Benth. is an economically important medicinal plant known to yield picrosides which have high medicinal value. Picroside I and picroside II are major picrosides associated with various bioactivities. The present work analyzed the expression of various genes of the picrosides biosynthesis pathway in different tissues of the plant in relation to the picrosides content. Eight full-length cDNA sequences namely, 1-deoxy-d-xylulose-5-phosphate synthase (2.317 kb), 1-deoxy-d-xylulose-5-phosphate reductoisomerase (1.767 kb), 4-diphosphocytidyl-2-C-methyl-d-erythritol kinase (1.674 kb), 4-hydroxy-3-methylbut-2-enyl diphosphate reductase (1.701 kb), acetyl-CoA acetyltransferase (1.545 kb), 3-hydroxy-3-methylglutaryl coenzyme A reductase (2.241 kb), isopentenyl pyrophosphate isomerase (987 bp) and geranyl diphosphate synthase (1.434 kb), were cloned to full-length followed by expression analysis of ten genes vis-à-vis picrosides content analysis. There is maximum accumulation of picrosides in leaf tissue followed by the rhizome and root, and a similar pattern of expression was found in all the ten genes. The genes responded to the modulators of the picrosides biosynthesis. Picrosides accumulation was enhanced by application of hydrogen peroxide and abscisic acid, whereas methyl jasmonate and salicylic acid treatment decreased the content.     

Combined metadoxine and garlic oil treatment efficaciously abrogates alcoholic steatosis and CYP2E1 induction in rat liver with restoration of AMPK activity

Alcoholic steatosis is the earliest and most common response to heavy alcohol intake, and may precede more severe forms of liver injury. Accumulation of fat, largely triglyceride, in hepatocytes results from the inhibition of fatty acid oxidation and excessive oxidative stress involving CYP2E1. This study evaluated the therapeutic effects of metadoxine, garlic oil or their combination on alcoholic steatosis. Feeding rats an alcohol-containing diet for 4 weeks elicited an increase in hepatic triglyceride content and induced CYP2E1. The concurrent administration of metadoxine and garlic oil (MG) to rats during the last week of the diet feeding efficaciously abrogated both fat accumulation and CYP2E1 induction as compared to the individual treatment at higher doses. Histopathology confirmed the ability of MG combination to inhibit lipid accumulation. Blood biochemistry verified improvement of liver function in rats treated with MG. Alcohol administration resulted in a decrease in AMP-activated protein kinase-alpha (AMPKalpha) phosphorylation, which was restored by MG treatments. Recovery of AMPK activity by MG was supported by an increase in acetyl-CoA carboxylase phosphorylation. Hepatic fatty acid synthase (FAS) expression was markedly decreased after alcohol consumption, which correlated with a decrease in AMPK activity and a commensurate increase in lipid content. Combined MG treatments caused restoration of the FAS level. These results demonstrate that the combination of MG effectively treats alcoholic steatosis with CYP2E1 inhibition, which may be associated with the recovery of AMPK activity, promising that the combination therapy may constitute an advance in the development of clinical candidates for alcoholic steatosis.     

The effect of folate-related SNPs on clinicopathological features,response to neoadjuvant treatment and survival in pre- and postmenopausal breast cancer patients

This study aimed to investigate the relationship of ten single nucleotide polymorphisms (SNPs) in the MTHFR, MTR, MTRR, DHFR, MTHFD1, TS, RFC1 and DNMT3b genes with cancer survival, therapeutic response to neoadjuvant chemotherapy and clinicopathological characteristics in 300 pre- and postmenopausal breast cancer patients of a Russian Western Siberian population. We found that the MTHFR 677CT genotype as well as combination of MTHFR 677CT and 677TT genotype was related to tumor size and estrogen-positive status in postmenopausal group. The RFC1 80А allele was associated with an increased risk of lymph node metastases among postmenopausal women. The MTHFR 677TT genotype was significantly correlated with a better progression-free survival in premenopausal patients. In contrast, a worse outcome was observed in this group patient with MTHFD1 1958AA genotype. In the multivariate analysis, the MTHFD1 1958AA genotype was identified as an independent prognostic factor for premenopausal breast cancer survival. Our findings provide evidence for associations of breast cancer survival with folate-related SNPs in a population of Western Siberian region of Russia and the MTHFD1 (1958G>A) may have additional prognostic value especially among premenopausal patients.     

Physiological and quantitative phosphoproteome analyses of drought stress-induced mechanisms in Malus baccata (L.) Borkh.

Limited information is available on how fruit crops respond to moderate drought stress. In the present study, we investigated how Malus baccata (L.) Borkh. a drought-tolerant genotype apple rootstock, responds to moderate drought stress. Our results for enzyme activity under moderate drought stress indicated that M. baccata produces osmosis-regulating substances. The phosphoproteins in the leaves were analyzed using iTRAQ technology. In total, 269 unique phosphopeptides, 304 phosphorylated sites, and 219 phosphoproteins were quantitatively analyzed in M. baccata. Furthermore, we identified 46 phosphoproteins in M. baccata whose phosphorylation levels significantly changed (PLSC). Among them, 22 PLSC phosphoproteins were found to be involved in metabolic processes that included carbon and nitrogen metabolism. This suggests that a systematic response pattern was generated in M. baccata and moderate drought stress resulted in a new homeostasis of carbon and nitrogen metabolism. The 14 differentially expressed mRNAs encoding phosphoproteins were analyzed by quantitative real-time PCR. Our study is the first to analyze the phosphoproteome of M. baccata and provides insights into the partial molecular regulatory mechanisms of M. baccata under moderate drought stress.