Fruit Quolity of'Gros Colman'Grapes Produced on Virus-free Vines

The Grape cultivar 'Gros Coleman'(Vitis vinifera)is the latest-maturing variety in japan,mainly cultivatde in green-houses in southern Okayama.Vines treated with virus-free treatments before raising in a nursery bed have been introduced in the last desade to improve the fuit quality,especially skin coloration and sugar content.However,some growers feel that the fruit taste from treated vines tends to deteriorate earlier than from untreated vines. We investigated change in the qualities of the berries produced on treated and untreated vines from October to January.After analysing skin color,berry turgidity,and juice constituents,we concluded that the palatability of berries on virus-free vines might be lessened in late December or thereafter of the rapid decrease in amino acids such as glutamic acid,glutamine,and alanine,which considerrably affects fruit taste.岡山県南部で施設栽培されている晩熟性ブドウの’グローコールマン’では、果実の品質を高めるためにウイルスフリー樹の導入が進められてきた。それによって、多くの場合は果実の着色や糖の蓄積が促進されるようになったが、樹によっては出荷最盛期の12月下旬になると果実の「張り」や食味が低下すると言われている。本研究で主産地の岡山市一宮地区内にある５ケ所の’グロー･コールマン’園で、ウイルスフリー樹と在来樹の果実の成熟を比較した結果、12月上旬から1月中旬までの間に果粒の「張り」や果汁の糖濃度が低下することは認められなかった。しかし、ウイルスフリー樹では果汁のアミノ酸が速く低下する傾向があり、それが食味の低下を引き起こす可能性があると推察される

Rapid transcriptional plasticity of duplicated gene clusters enables a clonally reproducing aphid to colonise diverse plant species

Background: The prevailing paradigm of host-parasite evolution is that arms races lead to increasing specialisation via genetic adaptation. Insect herbivores are no exception and the majority have evolved to colonise a small number of closely related host species. Remarkably, the green peach aphid, Myzus persicae, colonises plant species across 40 families and single M. persicae clonal lineages can colonise distantly related plants. This remarkable ability makes M. persicae a highly destructive pest of many important crop species. Results: To investigate the exceptional phenotypic plasticity of M. persicae, we sequenced the M. persicae genome and assessed how one clonal lineage responds to host plant species of different families. We show that genetically identical individuals are able to colonise distantly related host species through the differential regulation of genes belonging to aphid-expanded gene families. Multigene clusters collectively upregulate in single aphids within two days upon host switch. Furthermore, we demonstrate the functional significance of this rapid transcriptional change using RNA interference (RNAi)-mediated knock-down of genes belonging to the cathepsin B gene family. Knock-down of cathepsin B genes reduced aphid fitness, but only on the host that induced upregulation of these genes. Conclusions: Previous research has focused on the role of genetic adaptation of parasites to their hosts. Here we show that the generalist aphid pest M. persicae is able to colonise diverse host plant species in the absence of genetic specialisation. This is achieved through rapid transcriptional plasticity of genes that have duplicated during aphid evolution

Contribution of Root Hair Development to Sulfate Uptake in <i>Arabidopsis</i>

Root hairs often contribute to nutrient uptake from environments, but the contribution varies among nutrients. In Arabidopsis, two high-affinity sulfate transporters, SULTR1;1 and SULTR1;2, are responsible for sulfate uptake by roots. Their increased expression under sulfur deficiency (&#8722;S) stimulates sulfate uptake. Inspired by the higher and lower expression, respectively, of SULTR1;1 in mutants with more (werwolf [wer]) and fewer (caprice [cpc]) root hairs, we examined the contribution of root hairs to sulfate uptake. Sulfate uptake rates were similar among plant lines under both sulfur sufficiency (+S) and &#8722;S. Under &#8722;S, the expression of SULTR1;1 and SULTR1;2 was negatively correlated with the number of root hairs. These results suggest that both &#8722;S-induced SULTR expression and sulfate uptake rates were independent of the number of root hairs. In addition, we observed (1) a negative correlation between primary root lengths and number of root hairs and (2) a greater number of root hairs under &#8722;S than under +S. These observations suggested that under both +S and &#8722;S, sulfate uptake was influenced by the root biomass rather than the number of root hairs

SLIM1 Transcription Factor Promotes Sulfate Uptake and Distribution to Shoot, Along with Phytochelatin Accumulation, Under Cadmium Stress in Arabidopsis thaliana

Sulfur (S) assimilation, which is initiated by sulfate uptake, generates cysteine, the substrate for glutathione (GSH) and phytochelatin (PC) synthesis. GSH and PC contribute to cadmium (Cd) detoxification by capturing it for sequestration. Although Cd exposure is known to induce the expression of S-assimilating enzyme genes, including sulfate transporters (SULTRs), mechanisms of their transcriptional regulation are not well understood. Transcription factor SLIM1 controls transcriptional changes during S deficiency (&minus;S) in Arabidopsis thaliana. We examined the potential involvement of SLIM1 in inducing the S assimilation pathway and PC accumulation. Cd treatment reduced the shoot fresh weight in the sulfur limitation1 (slim1) mutant but not in the parental line (1;2PGN). Cd-induced increases of sulfate uptake and SULTR1;2 expressions were diminished in the slim1 mutant, suggesting that SLIM1 is involved in inducing sulfate uptake during Cd exposure. The GSH and PC levels were lower in slim1 than in the parental line, indicating that SLIM1 was required for increasing PC during Cd treatment. Hence, SLIM1 indirectly contributes to Cd tolerance of plants by inducing &minus;S responses in the cell caused by depleting the GSH pool, which is consumed by enhanced PC synthesis and sequestration to the vacuole

Evolutionary history of Hemerocallis in Japan inferred from chloroplast and nuclear phylogenies and levels of interspecific gene flow

The perennial herb genus Hemerocallis (Asphodelaceae) shows four flowering types: diurnal half-day, diurnal one-day, nocturnal half-day, and nocturnal one-day flowering. These flowering types are corresponding to their main pollinators, and probably act as a primary mechanism of reproductive isolation. To examine how the four flowering types diverged, we reconstructed the phylogeny of the Japanese species of Hemerocallis using 1615 loci of nuclear genome-wide SNPs and 2078 bp sequences of four cpDNA regions. We also examined interspecific gene flows among taxa by an Isolation-with-Migration model and a population structure analysis. Our study revealed an inconsistency between chloroplast and nuclear genome phylogenies, which may have resulted from chloroplast capture. Each of the following five clusters is monophyletic and clearly separated on the nuclear genome-wide phylogenetic tree: (I) two nocturnal flowering species with lemon-yellow flowers, H. citrina (half-day flowering) and H. lilioasphodelus (one-day flowering); (II) a diurnal one-day flowering species with yellow-orange flowers, H. middendorffii; (III) a variety of a diurnal half-day flowering species with reddish orange flowers, H. fulva var. disticha; (IV) another variety of a diurnal half-day flowering species with reddish orange flowers, H. fulva var. aurantiaca, and a diurnal one-day flowering species with yellow-orange flowers, H. major; (V) a diurnal half-day flowering species with yellow-orange flowers, H. hakuunensis. The five clusters are consistent with traditional phenotype-based taxonomy (cluster I, cluster II, and clusters III-V correspond to Hemerocallis sect. Hemerocallis, Capitatae, and Fulvae, respectively). These findings could indicate that three flowering types (nocturnal flowering, diurnal one-day flowering, and diurnal half-day flowering) diverged in early evolutionary stages of Hemerocallis and subsequently a change from diurnal half-day flowering to diurnal one-day flowering occurred in a lineage of H. major. While genetic differentiation among the five clusters was well maintained, significant gene flow was detected between most pairs of taxa, suggesting that repeated hybridization played a role in the evolution of those taxa