Metabolism of endogenous nitric oxide during growth and development of apple fruit

Nitric oxide (NO) is a key signaling molecule in different physiological processes of plants. To study the metabolism of endogenous NO in growth and development of apple fruit under normal physiological conditions, the changes of several relative components of NO metabolism including the contents of NO, l-arginine, S-nitrosothiols (RSNOs) and nitrite plus nitrate, the activities of l-arginine-dependent nitric oxide synthase (NOS) and nitrate reductase (NR) were analyzed using vegetal ‘Gold Delicious’ and ‘Fuji’ apples as tested materials. The endogenous NO and l-arginine contents, as well as the l-arginine-dependent NOS activity in young fruit reached the highest value. The NOS activity was dependent on l-arginine and β-NADPH, and inhibited by a well known NOS inhibitor. The NR activity in apple fruit had not been detected. Endogenous NO production depended on l-arginine-dependent NOS but not NR. The content of RSNOs tended to peak in the fruit enlarging period and then declined. Similarly, the nitrate content increased in early stage of fruit growth, but in late stage, it undulated greatly. Compared to RSNOs and nitrate, the change of nitrite content was in accordance with that of endogenous NO. In general, RSNOs and nitrite could reflect the removal mechanism of NO relatively well.     

Phenolic compounds and antioxidant activity of the apple flesh and peel of eleven cultivars grown in Brazil

The total phenolic, flavanol, monomeric anthocyanin contents and the antioxidant activity of flesh and peel of 11 apple cultivars from Brazil were investigated. Concentrations of the parameters measured differed significantly among the apple cultivars and were highest in the peel compared to the flesh. Total phenolic content (mg GAE/100 g fresh matter) ranged from 128.3 (Golden Delicious) to 212.0 (Epagri-F₅P₂₈₃) in the flesh and 304.6 (Golden Delicious) to 712.6 (Catarina) in the peel. Total flavanol content (mg CAE/100 g fm) varied from 11.7 (Epagri-SJ11) to 28.2 (Epagri-F₄₃P₂₃) and from 32.4 (Epagri-SJ11) to 147.7 (Catarina) in the flesh and peel, respectively. COOP-24 peel had the highest total anthocyanin content. The Epagri-F5P283 and Epagri-F43P23 flesh and Catarina peel had the highest antioxidant activity while Golden Delicious flesh and peel had the lowest. The total phenolic content and antioxidant activity were significantly correlated in both flesh (R² = 0.717) and peel (R² = 0.716). The contribution of phenolics to the antioxidant activity in peel suggests that their removal may induce a significant loss of antioxidants.     

Effects of position on canopy and harvest time on fruit physico-chemical and antioxidant properties in different apple cultivars

Fruit from Granny Smith, Fyriki, Fuji Kiku 8, and Imperial Double Red Delicious apple (Malus domestica Borkh.) trees planted in single or double rows, were harvested from different positions in the canopy, during the last month before commercial harvest. Fruit physico-chemical and antioxidant capacity, using the radical DPPH, were measured, in skin and flesh tissue. Greater total phenol content and total antioxidant capacity per fresh weight and serving portion of skin and flesh tissue, were found in Imperial Double Red Delicious and Fyriki apples, compared to Granny Smith and Fuji Kiku 8. The variation among cultivars in antioxidant contents was greater in peeled, compared with unpeeled fruit, highlighting the importance of eating unpeeled fruit. During the last two weeks before commercial harvest the total phenol content and total antioxidant capacity per fresh weight increased in skin of Granny Smith (by 24% and 42%, respectively) and Fuji Kiku 8 (by 19% and 27%, respectively). Fruit from the more sun—exposed parts of canopy had usually better red coloration and the effect was more pronounced in Fuji Kiku 8 and Fyriki, followed by Imperial Double Red Delicious and a lower effect was found in Granny Smith. Greater total soluble solid content, but not flesh firmness, were also found in fruit from the more sun—exposed parts of canopy, in all cultivars. The skin of fruit from the upper positions in the canopy had greater total phenol content and total antioxidant capacity, in all cultivars, apart from Fyriki. Antioxidant contents in flesh tissue were also greater in the upper positions of canopy in Fuji Kiku 8 and Imperial Double Red Delicious, and to our knowledge this is the first report on plant canopy effects on apple flesh antioxidant compounds.     

Optimising quality-parameters of apple cv. ‘Pigeon’ by adjustment of nitrogen

To improve the productivity and quality of the apple cultivar ‘Pigeon’ the influence of 5 fertigation levels (14, 42, 70, 112, 224 mg N/l) and 3 widths of herbicide strip (0.2, 0.5, 1.0 m) were investigated on growth, yield and post-harvest quality/colour development of fruit. ‘Pigeon’ apples are picked when ca. 20% of the fruit skin has turned red, the fruit are then exposed to a sunning period on the orchard floor of 2–3 weeks to enhance red colour development (80% red skin); however the internal quality deteriorates during this period. Fruit drop occurs if fruit are left on the tree to develop colour. This study focused on how to reduce the length of the post-harvest sunning period to maximise both colour development and fruit quality. It was demonstrated that 14 mg N/l resulted in a low yield, small fruit, low vegetative growth, and low N content in leaf dry matter, but good fruit colour development. Excessive N fertigation (224 mg N/l) did not produce the significantly highest yield or the largest fruit, but it did enhance vegetative growth and resulted in less fruit colouration. N fertigation influenced optimal picking date; higher N fertigation delayed the time of picking, and increased the incidence of green fruit. Fruit from the high-N treatments required more days of post-harvest sunning to obtain the comparable red skin colour than fruit from the lower N-treatments. However, when all treatments were picked at ca. 20% fruit coloration it was not possible to reduce the length of post-harvest sunning period by N-supply. Most of the post-harvest colour development occurred within the first 6–9 days following harvest; colour developed on both sides but was enhanced on the shade side of the fruit. The shade side of the fruit had a greater potential for better red colour development than the blush side of the fruit.     

An intact mitochondrial cox1 gene and a pseudogene with different genomic configurations are present in apple cultivars ‘Golden Delicious’ and ‘Delicious’: Evolutionary aspects

We have characterized the mitochondrial cox1 gene copies in two apple cultivars ‘Golden Delicious’ and ‘Delicious’. Both the cultivars contained an intact copy and a truncated copy of cox1. The intact ‘Golden Delicious’ and ‘Delicious’ cox1 genes, designated G-cox1 and D-cox1, respectively, were both found to be actually transcribed to give an RNA of approximately 1.7 kb. The two intact cox1 and two truncated copies (G-φcox1 and D-φcox1) shared a common 1115-bp segment flanked by four combinations of two different 5′- and 3′-sequences. PCR assay demonstrated that the configurations bearing G-cox1 and G-φcox1 existed in substoichiometric amounts within the mitochondrial genome of ‘Delicious’ whereas substoichiometric molecules carrying D-φcox1 were present in the ‘Golden Delicious’ mitochondrial genome. Although ancestor/descendant relationships cannot be inferred between the G-cox1 and D-cox1 arrangements, the results led us to hypothesize that (1) the 1115-bp segment containing part of the progenitor cox1 was duplicated, thereby generating a pseudo-cox1 copy, and (2) this was followed by homologous recombination across a portion of the 1115-bp repeats which gave rise to the descendant cox1 and pseudo-cox1 arrangements.     

苹果新品种——华脆的选育

华脆是利用金冠为母本,惠为父本杂交选育而成的晚熟、红色、鲜食加工兼用苹果新品种.该品种果实长圆形或圆锥形,平均单果质量200 g,果实底色黄绿,果面鲜红色及浓红条纹;果面光洁,外观漂亮;果肉黄白色、松脆,汁液多,风味甜酸,有香气;可溶性固形物含量12.8%,可溶性糖10.1%,果实硬度8.1kg·cm-2,可滴定酸含量...     

苹果内根-贝壳杉烯氧化酶基因的克隆及序列分析

内根-贝壳杉烯氧化酶(KO)是赤霉素合成代谢的关键酶。以苹果(Malus×domestica Borkh.)品种富士(Fuji)为供试材料,应用同源克隆和RACE方法从其茎尖中克隆到KO的cDNA全长序列,命名为MdKO,GenBank登录号:AY563549,其长度为1 859 bp。MdKO的开放性阅读框(ORF)编码514个氨基酸残基,推断其相对分子量为58.9 ku,等电点为7.63。氨基酸同源性分析表明,MdKO与已报道的其他植物的KO氨基酸序列具有较高的相似性;氨基酸聚类分析表明,苹果和梨首先聚类,其次是葡萄;序列结构分析表明MdKO属于细胞色素超家族P450系,具有细胞色素P450的血红素结构域FXXGXRXCXG和跨膜结构域;亚细胞定位分析发现MdKO可能位于内质网膜上。     

在滴灌肥条件下木醋液对马铃薯产量和品质的影响

种植马铃薯时,在施用滴灌肥条件下,木醋液作为植物生长调节剂对马铃薯实施喷洒叶片和随滴灌肥灌根2个处理,结果显示：木醋液能够提高马铃薯的产量和品质。在该试验条件下,喷洒叶片效果最好。     

Wound-induced H2O2 and resistance to Botrytis cinerea decline with the ripening of apple fruit

Fruit ripening is a developmental process and is associated with increased susceptibility to mechanical injury, which favours Botrytis cinerea infection. Using ‘Gala’ apples harvested at different stages of ripening, we demonstrated that wounding can activate initial H₂O₂ accumulation and wound healing ability to defend against B. cinerea penetration. Delaying the harvest date attenuated those responses. Superoxide dismutase, peroxidase and catalase, which are all involved in H₂O₂ metabolism, were differentially activated by wound stress depending on the stage of fruit maturity. Mature fruit were less able to respond to wounding by increasing phenylalanine ammonia lyase and peroxidase activity, which are associated with reduced phenolics and lignin content in local wound sites. The reduced response in late-harvested fruit contributes to the fruit ripening-induced loss of wound healing ability and increases susceptibility to B. cinerea. In addition, the rapid increase of H₂O₂ content immediately after wounding in early-harvested fruit was followed by increased phenylalanine ammonia lyase and peroxidase activity. In late-harvested fruit, the reduced ability to increase phenylalanine ammonia lyase and peroxidase activity in response to wounding was consistent with ripening-reduced generation of H₂O₂ early after wounding, leading to reduced resistance to B. cinerea. Thus, H₂O₂ accumulation in response to wounding is modulated by fruit maturity and is required for efficient wound healing and resistance to B. cinerea.     

金红苹果树(GM256中间砧)负载量对叶片光合产物影响的研究

通过金红苹果树(CM256中间砧)不同负载量的发育枝(F)、无果短枝(W)、有果短枝(Y)叶片的光合产物——可溶性糖和淀粉量的测定。结果表明：随着负载量的增大,发育枝叶片的可溶性糖含量稍有升高,短枝叶片的可溶性糖含量下降,各类枝叶片的淀粉含量均呈下降趋势。