Mapping yield-associated QTL in globe artichoke

Globe artichoke (Cynara cardunculus var. scolymus), whose immature inflorescences (capitula) are consumed as a vegetable all over the world, contributes significantly to the agricultural economy of the Mediterranean basin. Here, we describe a QTL (quantitative trait loci) analysis aimed at elucidating the mode of inheritance of seven main and first-order capitulum traits. Mapping was carried out in an F₁ population obtained by crossing a globe artichoke with a cultivated cardoon (C. cardunculus var. altilis). A total of 100 QTL associated with the seven capitulum traits were mapped to 23 chromosomal regions, scattered over 12 of the 17 linkage groups. Among these, 73 were expressed in both growing seasons, while the others were only detected in one season. Up to nine QTL per trait were identified, and major QTL, responsible for some 20 % of the phenotypic variation, were detected for capitulum length, diameter, shape index and fresh weight. The QTL for correlated traits frequently co-localized, most likely due to pleiotropy. This study represents the first report on yield traits QTL in globe artichoke. The QTL identified, along with linked markers, particularly those located in four hot-spot QTL regions are of practical interest for crop improvement based on marker-assisted breeding.     

Host range and properties of artichoke yellow ringspot virus

The biological, serological and physico-chemical properties of one isolate of artichoke yellow ringspot virus (AYRV) from Greece and another from Italy were compared. Both isolates infected 56 herbaceous species and there were few differences between them in the symptoms they caused. During purification they behaved identically and both tended to aggregate. Virus particles were isometric and measured c. 30 nm in diameter. In CsCl, virus sedimented as mixed aggregates of empty and full particles with buoyant densities varying from 1.20–1.30 g/ml and from 1.40–1.53 g/ml, respectively. The coat protein of AYRV contains a single polypeptide of mol. wt 53000 and the genome consists of two species of single-stranded RNA with mol. wts 2.17 × 10⁶ (RNA-1) and 1.85 × 10⁶ (RNA-2) daltons, estimated under denaturing conditions. The two virus isolates are serologically very closely related but are unrelated to 28 other plant viruses with isometric particles. The characteristics of AYRV suggest that it is a possible member of the nepovirus group.     

Batch and continuous solid-phase fermentation of Jerusalem artichoke tubers

Two strains of Kluyveromyces marxianus were evaluated for their ability to ferment Jerusalem artichoke tuber pulp to ethanol under pH levels ranging from 2.0–6.3. Bacterial contamination was prevented in batch, solid-phase fermentation when pulp was initially adjusted to pH 3.5 or less, and maximal yeast populations occurred at pH 3.0–3.5. Fermentation times were also shortest for both yeast (13–18 h) and ethanol (48–64 h) production when pulp pH was in this range. However, ethanol yields (41–53% of theoretical) and fermentation efficiencies (68–78%) were somewhat lower than expected, with only 6.6–7.2% (v/v) ethanol produced by strain Y-1598 and 5.7–6.9% produced by strain Y-1550. Based on these parameters, the continuous solid-phase fermentor was operated for 396 h using strain Y-1598. The pH of pulp entering the fermentor was adjusted to 2.5 to compensate for partial neutralization by the mild steel of the fermentor. This resulted in fermenting pulp with a pH of 3.0–3.5, and therefore no contamination. Pulp exiting the fermentor after 72 h contained 6.9 × 10⁸ yeast cells/ml and 7.3% ethanol, which represented 55.9% of the theoretical yield and a fermentation efficiency of 73.3%. Further modifications (partial acid hydrolysis, finer grinding, etc.) should permit higher yields.     

Processing and fermentation of Jerusalem artichoke for ethanol production

Summary Processing and fermentation trials on Jerusalem artichoke (Helianthus tuberosus L.) tubers, and on pure inulin media were carried out. Acid and thermal treatments, pure and mixed cultures of yeast, and enzyme preparations were investigated. Best ethanol yields on either substrate were obtained with pH 2 thermal treatments, resulting in 131.6 liters ethanol per metric ton fresh tuber.     

Transport and metabolism of D-lactate in Jerusalem artichoke mitochondria

We report here initial studies on D-lactate metabolism in Jerusalem artichoke. It was found that: 1) D-lactate can be synthesized by Jerusalem artichoke by virtue of the presence of glyoxalase II, the activity of which was measured photometrically in both isolated Jerusalem artichoke mitochondria and cytosolic fraction after the addition of S-D-lactoyl-glutathione. 2) Externally added D-lactate caused oxygen consumption by mitochondria, mitochondrial membrane potential increase and proton release, in processes that were insensitive to rotenone, but inhibited by both antimycin A and cyanide. 3) D-lactate was metabolized inside mitochondria by a flavoprotein, a putative D-lactate dehydrogenase, the activity of which could be measured photometrically in mitochondria treated with Triton X-100. 4) Jerusalem artichoke mitochondria can take up externally added D-lactate by means of a D-lactate/H(+) symporter investigated by measuring the rate of reduction of endogenous flavins. The action of the d-lactate translocator and of the mitochondrial D-lactate dehydrogenase could be responsible for the subsequent metabolism of d-lactate formed from methylglyoxal in the cytosol of Jerusalem artichoke.     

The purine nucleosidases of Jerusalem artichoke shoots

Extracts from Jerusalem artichoke shoots exhibited adenosine and inosine—guanosine nucleosidase activities. The results suggest the existence of two     

Phosphoenolpyruvate metabolism in Jerusalem artichoke mitochondria

We report here initial studies on phosphoenolpyruvate metabolism in coupled mitochondria isolated from Jerusalem artichoke tubers. It was found that:

(1)

phosphoenolpyruvate can be metabolized by Jerusalem artichoke mitochondria by virtue of the presence of the mitochondrial pyruvate kinase, shown both immunologically and functionally, located in the inner mitochondrial compartments and distinct from the cytosolic pyruvate kinase as shown by the different pH and inhibition profiles.

(2)

Jerusalem artichoke mitochondria can take up externally added phosphoenolpyruvate in a proton compensated manner, in a carrier-mediated process which was investigated by measuring fluorimetrically the oxidation of intramitochondrial pyridine nucleotide which occurs as a result of phosphoenolpyruvate uptake and alternative oxidase activation.

(3)

The addition of phosphoenolpyruvate causes pyruvate and ATP production, as monitored via HPLC, with their efflux into the extramitochondrial phase investigated fluorimetrically. Such an efflux occurs via the putative phosphoenolpyruvate/pyruvate and phosphoenolpyruvate/ATP antiporters, which differ from each other and from the pyruvate and the adenine nucleotide carriers, in the light of the different sensitivity to non-penetrant compounds. These carriers were shown to regulate the rate of efflux of both pyruvate and ATP. The appearance of citrate and oxaloacetate outside mitochondria was also found as a result of phosphoenolpyruvate addition.

     

Phosphoenolpyruvate metabolism in Jerusalem artichoke mitochondria

We report here initial studies on phosphoenolpyruvate metabolism in coupled mitochondria isolated from Jerusalem artichoke tubers. It was found that: (1) phosphoenolpyruvate can be metabolized by Jerusalem artichoke mitochondria by virtue of the presence of the mitochondrial pyruvate kinase, shown both immunologically and functionally, located in the inner mitochondrial compartments and distinct from the cytosolic pyruvate kinase as shown by the different pH and inhibition profiles. (2) Jerusalem artichoke mitochondria can take up externally added phosphoenolpyruvate in a proton compensated manner, in a carrier-mediated process which was investigated by measuring fluorimetrically the oxidation of intramitochondrial pyridine nucleotide which occurs as a result of phosphoenolpyruvate uptake and alternative oxidase activation. (3) The addition of phosphoenolpyruvate causes pyruvate and ATP production, as monitored via HPLC, with their efflux into the extramitochondrial phase investigated fluorimetrically. Such an efflux occurs via the putative phosphoenolpyruvate/pyruvate and phosphoenolpyruvate/ATP antiporters, which differ from each other and from the pyruvate and the adenine nucleotide carriers, in the light of the different sensitivity to non-penetrant compounds. These carriers were shown to regulate the rate of efflux of both pyruvate and ATP. The appearance of citrate and oxaloacetate outside mitochondria was also found as a result of phosphoenolpyruvate addition.     

Purification and properties of the arginase from Jerusalem artichoke tubers

Arginase [l-arginine amidinohydrolase] in Jerusalem artichoke tubers occurs in a particulate fraction from which it was released in active form by detergent treatment. The particulate enzyme was purified 450-fold with ca 3% yield. The enzyme has a MW of ca 140 000 and pI of 5.3. The enzyme required Mn²⁺ for activity and was unstable when Mn²⁺ was removed. In tissue extracts the K_m for arginine was ca 1OmM, but when purified the K_m (arginine) was 145 mM. The artichoke arginase was shown to be more substrate specific than other plant and animal arginases which have been described, and to be very sensitive to competitive inhibition by indospicine, ornithine and citrulline.     

Photosynthetic characterization of Jerusalem artichoke during leaf expansion

Gas exchange, chlorophyll a fluorescence and modulated 820 nm reflection were investigated to explore the development of photosynthesis in Jerusalem artichoke (Helianthus tuberosus L.) leaves from initiation to full expansion. During leaf expansion, photosynthetic rate (Pn) increased and reached the maximal level when leaves were fully expanded. The same change pattern was also found in the stomatal conductance and chlorophyll content. Lower Pn could not be ascribed to the higher stomatal resistance in developing leaves, as intercellular CO₂ concentration was not significantly lower in these leaves. Lower Pn partly resulted from the lower actual photochemical efficiency of PSII in developing leaves, as more excited energy was dissipated through non-photochemical quenching. The development of primary photochemical reaction and electron transport in the donor side of PSII was completed in the initiating leaves. However, the development of electron transport in the acceptor side of PSII was not accomplished until leaves were fully expanded, indicated by the change in probability that an electron moves further than primary quinone (ψo). PSI activity changed in parallel with ψo suggesting that PSI cooperated well with PSII during leaf expansion. It should be stressed that the development of carbon fixation process was later than primary photochemical reaction but earlier than photosynthetic electron transport during leaf expansion. The later development of photosynthetic electron transport may reduce the production of reactive oxygen species from Mehler reaction, particularly under low carbon fixation.     

High-yield ethanol production from Jerusalem artichoke tubers

Fermentation conditions were optimized for the production of ethanol from Jerusalem artichoke with a strain of Saccharomyces cerevisiae able to use high-concentration juice and undiluted pulp. Yields (95 to 125 g ethanol/l=85 to 98% of the theoretical value) exceeded those obtained with strain of Kluyveromyces used classically.The authors are with the Laboratoire de Pharmacognosie et Biotechnologie, UFR Pharmacie, 28 Place Henri-Dunant, 63001 Clermont-Ferrand Cédex, France. H. Pourrat is the corresponding author.     

菊芋生长发育动态及光合性能指标变化研究

以‘青芋1号’菊芋为材料,通过田间试验对菊芋全生育周期的器官生长发育、干物质积累分配动态以及光合性能指标变化进行了连续观察研究。结果表明,地上部器官生长量与干物质积累量均在第18周达到峰值,之后开始迅速转向块茎生长,块茎膨大速率在第18周和第2I周有2个高峰,块茎干物质积累则经过了块茎形成、块茎形成与膨大并行、块茎迅速膨大3个阶段,峰值出现在第21周;第18周干物质开始从地上部器官向块茎转移,此时总干物质量达到峰值,之前干物质主要暂时贮存在茎内。收获时,块茎干物质量达到15．76t·hm^-2,收获指数在0．65以上;叶面积指数、光合势、净同化率与叶绿素含量在植株快速生长期和地上部干物质开始向块茎转移前一段时期均有高峰出现。     

Isoperoxidases in jerusalem artichoke in relation to tuberization and dormancy

Peroxidase activity and isoenzyme pattern were investigated in buds and tubers of Jerusalem artichokes in relation to induction and breaking of dormancy. Peroxidase activity per unit soluble protein is the highest in the dormant stage. Conditions leading to growth,i.e. release of dormancy by the cold, stimulation of axial growth by gibberellic acid or stimulation of radial growth (tuberization) by kinetin, cause rapid loss of total peroxidase activity together with a decrease of intensity of the most cathodic isoperoxidases. Induction of dormancy by AMO-1618 increases peroxidase activity mainly through the same cathodic isoenzymes. The role of the cathodic isoperoxidases is discussed in relation to auxin catabolism and the genesis of oxygenation products inhibitory to plant growth.     

Production and fingerprinting of virus-free clones in a reflowering globe artichoke

Most of the 24 viruses which infect globe artichoke are detrimental to the crop’s performance and hamper the development of a nursery activity in the respect of current EU legislation. We describe a procedure to sanitize globe artichoke “Brindisino” from Artichoke Italian latent virus (AILV) and Artichoke latent virus (ArLV), while preserving its valuable early flowering trait. ArLV was successfully eliminated by meristem-tip culture, while AILV was removed when two rounds of meristem-tip culture were spaced out with in vitro thermotherapy. In vivo thermotherapy, followed by meristem-tip culture, was also successful in producing virus-free material but was less efficient in terms of the number of plants recovered post treatment. Due to the multi-clonal composition of the populations at present in cultivation, the selected and sanitised clones were fingerprinted by applying microsatellite and AFLP (amplified fragment length polymorphism) markers. One AFLP primer combination produced 28 informative fragments used to evaluate genetic relatedness among the clones in study. Our results demonstrates that AFLP-based molecular fingerprinting enables to verify the true to clone correspondence in nurseries, ensure the effective correspondence between the real and the declared identity of a clone, so that to avoid commercial frauds, and might represents a valuable tool for assessing somaclonal variation occuring during ‘in vitro’ propagation.     

Nutritive value of Indian bread-root,squaw-root,and Jerusalem artichoke

Three native species formerly used as food plants by the Indians of western Canada were analyzed for nutritive value. The species were Indian bread-root (Psoralea esculenta Pursh, squaw-root (Perideridia gairdneri(Hook & Arn.) Mathias), and Jerusalem artichoke (Helianthus tuberosusL. var. subcanescensGray. Protein scores, which are estimates of protein quality based on egg protein with a value of 100, were: squaw-root, 81;Jerusalem artichoke, 58;and Indian bread-root, 36. Squaw-root proved to be nutritionally the best among the 3 species and could also be a useful source of vitamins A and C and of potassium. Both squaw-root and Indian bread- root are also valuable sources of food energy,and all 3 plants, especially Indian bread- root, are good sources of lysine and therefore good supplements for cereals.