Quince Genotypes Research Articles

Oxidative stress responses and root lignification induced by Fe deficiency conditions in pear and quince genotypes

We analysed Pyrus communis cv. Conference and Cydonia oblonga BA29, differently tolerant to lime-induced chlorosis, to identify the key mechanisms involved in their different performance under Fe deficiency induced by the absence of Fe (-Fe) or by the presence of bicarbonate (+FeBic). Under our experimental conditions, a decrease in root elongation was observed in BA29 under bicarbonate supply. Superoxide dismutase (SOD) and peroxidase (POD) activities were analysed and the relative isoforms were detected by native electrophoresis. The data obtained for both genotypes under -Fe and for BA29 +FeBic suggest the occurrence of overproduction of reactive oxygen species (ROS) and, at the same time, of a scarce capacity to detoxify them. The detection of ROS (O(2)(-) and H(2)O(2)) through histochemical localization supports these results and suggests that they could account for the modifications of mechanical properties of the cell wall during stress adaptation. On the other hand, in the cv. Conference +FeBic, an increase in non-specific POD activity was detected, confirming its higher level of protection in particular against H(2)O(2) accumulation. Peroxidases involved in lignification were assayed and histochemical analysis was performed. The results suggest that only in BA29 under bicarbonate supply can the presence of ROS in root apoplast be correlated with lignin deposits in external layers and in endodermis as a consequence of the shift of PODs towards a lignification role. We suggest that in BA29 the decrease in root growth could impair mineral nutrition, generating susceptibility to calcareous soils. In the cv. Conference, the allocation of new biomass to the root system could improve soil exploration and consequently Fe uptake.

Characterization of quince (Cydonia oblonga Mill.) cultivars using SSR markers developed for apple

Quince (Cydonia oblongaMill.) is a minor fruit crop, which is primarily used for marmalade, jam and sauce.Very few quince cultivars are known all over the world and in many cases similar names are used for presumably different cultivars. The aim of the present study was to evaluate and characterize the genetic diversity of 36 quince cultivars and selections with SSR markers. Seven out of 8 SSR markers designed from apple sequences could successfully yield amplification also in quince cultivars. Number of alleles per locus ranged from 2 to 3 alleles. These allele numbers are quite low when compared to apple. It is supposed to be the consequence of a genetic bottleneck. In spite of the low allele number per locus, the 36 quince cultivars formed 30 different genotypes. The ratio of homozygosity was low, which might be coupled with the self-(in)compatibility phenotype of quinces. SSR markers proved unable to differentiate putatively closely related cultivars (e.g. ‘Bereczki’ and ‘Bereczki bôtermő’). In general, the level of polymorphism among the tested quince genotypes was much restricted due to the low allele number detected. However, it must be considered that the number of analysed SSR loci is not enough high to estimate the overall heterozygosity of the quince genome. Further experiments are needed and the SSR markers proved to be a reliable and useful tool for such analyses.

Differential responses in pear and quince genotypes induced by Fe deficiency and bicarbonate

Most of the studies carried out on Fe deficiency condition in arboreous plants have been performed, with the exception of those carried out on plants grown in the field, in hydroponic culture utilizing a total iron depletion growth condition. This can cause great stress to plants. By introducing Fe deficiency induced by the presence of bicarbonate, we found significant differences between Pyrus communis L. cv. Conference and Cydonia oblonga Mill. BA29 and MA clones, characterized by different levels of tolerance to chlorosis. Pigment content and the main protein-pigment complexes were investigated by HPLC and protein gel blot analysis, respectively. While similar changes in the structural organization of photosystems (PSs) were observed in both species under Fe deficiency, a different reorganization of the photosynthetic apparatus was found in the presence of bicarbonate between tolerant and susceptible genotypes, in agreement with the photosynthetic electron transport rate measured in isolated thylakoids. In order to characterize the intrinsic factors determining the efficiency of iron uptake in a tolerant genotype, the main mechanisms induced by Fe deficiency in Strategy I species, such as Fe3+-chelate reductase (EC 1.16.1.7) and H+-ATPase (EC 3.6.3.6) activities, were also investigated. We demonstrate that physiological and biochemical root responses in quince and pear are differentially affected by iron starvation and bicarbonate supply, and we show a high correlation between tolerance and Strategy I activation.

Response of the Quince Genotypes BA 29 and EMA Used as Pear Rootstocks to Boron and Salinity

BA 29 and EMA (Cydonia oblonga L.) plants were grown in a 1:1 sand:perlite mixture and irrigated with nutrient solutions containing two B concentrations (0.025 and 0.2 mM) combined with two salinity (electrical conductivity, EC) levels (0.75 and 4 dS-m-1). The lowest growth of plants was recorded when 0.2 mM B was combined with 4 dS-m-1 in the nutrient solution. As salinity (EC) level increased from 0.75 to 4 dS-m-1, P, Ca and Fe concentrations of leaves decreased. The potassium concentration of leaves of both rootstocks increased, as salinity levels (induced by KCl) increased. The two quince genotypes respond differently for the same treatments, indicating a genotypic effect.

Evaluation of BC Williams and PI1/6 pear cultivars for their compatibility with 49 quince genotypes and their susceptibility to fire blight: Short communicaton

In this study, the compatibility of the pear cultivars PI1/6 and BC Williams with 49 quince genotypes was evaluated. The results showed that the cv. PI1/6 had a good compatibility with several of the quince genotypes, and the cv. BC Williams only with a few of them. Differences were also found in their susceptibility to fire blight (Erwinia amylovora). The cultivar PI1/6 was very susceptible, while the cultivar BC Williams was relatively tolerant.

Characterization of juice in fruits of different Chaenomeles species

The juice in fruits of 21 genotypes of Japanese quince ( Chaenomeles japonica), 1 genotype of Chinese quince ( C. cathayensis), 1 genotype of flowering quince ( C. speciosa) and 1 genotype of a hybrid taxon ( C. × superba), representing plant breeding material, was extracted and characterized. The content of juice in the fruits varied between 41% and 52%, on fresh weight basis. The juice was very acidic (pH 2.6 and a titratable acidity of 3.5% calculated as anhydrous citric acid, on average) and transparent (52 NTU, on average), with low density and viscosity. The content of soluble solids was also low (7.1°Brix, on average). Proteins constituted 26 mg/100 ml juice on average, but no soluble polysaccharides were present. A high content of vitamin C (59 mg/100 ml juice, on average) and phenols (284 mg/100 ml juice, on average), beside the high acidity of the juice, suggests that chaenomeles juice may be an interesting raw material as ingredient for the food industry and a source of valuable substances. A principal components analysis separated the Japanese quince genotypes from the other genotypes studied, thus indicating a clear difference in the characteristics and chemical composition of the juice.

Pectins in the fruits of Japanese quince ( Chaenomeles japonica)

The pectin content, composition and physico-chemical properties were studied in the fruits of two genotypes of Japanese quince. On average, the fruits contained 11 g pectins/100 g dry fruit and 1.4 g pectins/100 g fresh fruit. A sequential extraction was used to isolate the pectins from the fruits. The cells from the flesh were examined using a confocal laser scan microscope, fresh and after each extraction step of the sequence. The dilute acid conditions were the most efficient for pectin extraction. Pectins extracted by water or potassium oxalate had higher (>600 ml/g) intrinsic viscosities than the pectins extracted by dilute acid (<400 ml/g). Anionic exchange chromatography was performed on the acid-extracted pectins. They were constituted of four populations, the first one being mainly composed of arabinans, the second one of homogalacturonans, the third one of rhamnogalacturonans. The composition of the last one varied with the genotype studied.

Dietary fibre and cell-wall polysaccharides in the fruits of Japanese quince (Chaenomeles japonica)

The dietary fibre in the fruits of 12 genotypes of Japanese quince (Chaenomeles japonica) and 1 genotype of flowering quince (Chaenomeles speciosa) were prepared using two different methods: the alcohol insoluble solid (AIS) preparation; and the Association of Official Analytical Chemists (AOAC) method for total as well as for soluble and insoluble fibre. The two methods resulted in similar but significantly different estimates. No interaction was revealed between the methods and the genotypes studied. For content of total dietary fibre, three main groups could be distinguished: a group containing a low amount of fibre (three genotypes, 28–30 g/100 g dry matter), a group containing a medium amount of fibre (nine genotypes, 30–36 g/100 g dry matter) and an isolated genotype (Chaenomeles speciosa) that contained a considerable amount of fibre (38 g/100 g dry matter). The amount and the nature of monomeric sugars in the constitutive polysaccharides of the fibres were determined after total hydrolysis of the AIS or the total dietary fibre (TDF). The fibre contained mostly pectic and cellulosic polysaccharides. Analysis of the fibre from different parts of the fruits of two genotypes showed that they differed in their proportion of constituent polysaccharides (cellulose, hemicelluloses and pectic polysaccharides).

Response to iron‐deficiency stress of pear and quince genotypes1

Abstract Roots of iron (Fe)‐efficient dicots react to Fe‐deficiency stress by strongly enhancing the ferric (Fe3+)‐reductase system and by lowering the rhizo‐sphere pH. In this study, we tested whether such adaptation mechanisms characterize pear and quince genotypes known to have differential tolerance to calcareous and alkaline soils. Two trials were performed using micropagated plants of three quince rootstocks (BA29, CTS212, and MC), three Pyrus communis rootstocks (OHxF51 and two selections obtained at the Bologna University: A28 and B21) and of two pear cultivars (Abbé Fétel and Bartlett, own‐rooted). In the first trial, plants were grown in a nutrient solution with [Fe(+)] and without [Fe(‐)] Fe for 50 days. Their root Fe‐reducing capacity was determined colorimetrically using ferrozine and FeEDTA, and Fe uptake of Fe(+) plants was estimated. In the second trial, the rhizosphere pH of plants grown in an alkaline soil was measured by a micro‐electrode. With the only exception of pears OHxF51 and A28, whose Fe‐reduction rates were similar in Fe(+) and Fe(‐) plants, the Fe‐deficiency stress resulted in a significant decrease in Fe reduction. Among the Fe(‐) plants, the two pear cultivars, OHxF51 and A28, had a higher Fe‐reducing capacity than the quince rootstocks and the cv. Abb6 F. When plants were pre‐treated with Fe, reduction rate was highest in the P. communis rootstocks, intermediate in the own‐rooted cultivars, and lowest in the quinces. Root Fe‐reducing capacity of Fe(+) plants proved to be linearly and positively correlated with Fe uptake and root proton release. Rhizosphere pH was highest in quince MC, intermediate in the other two quinces and in the cv. Abbe F., and lowest in the pear rootstocks and in the cv. Bartlett. Our results indicate that roots of pear and quinces do not increase their ability to reduce the Fe under Fe‐deficiency stress. The genotypical differential tolerance to Fe chlorosis likely reflects differences in the standard reductase system and in the capacity of lowering the pH at the soil/root interface. The determination of the root Fe‐reducing capacity is a promising screening technique for selecting pear root‐stocks efficient in taking up Fe.

Response to Iron-deficiency Stress of Pear Genotypes

Pear rootstocks differ in tolerance to calcareous and alkaline soils. Roots of Fe-efficient dicots react to Fe-deficiency stress by strongly enhancing the Fe3+-reductase system, termed turbo-reductase, and by lowering the rhizosphere pH. In this study, we tested whether such adaptation mechanisms characterize pear and quince genotypes. Two trials were performed using micropropagated plants of three quince rootstocks (BA29, CTS212, and MC), three Pyrus communis rootstocks (OH × F51 and two selections obtained at Bologna Univ.: A28 and B21) and of two pear cultivars (Abbé Fétel and Bartlett, own-rooted). In the first trial, plants were grown in a nutrient solution with [Fe(+)] and without iron [Fe(–)] for 50 days. Their root iron-reducing capacity (IRC) was determined colorimetrically, using ferrozine and Fe-EDTA, and Fe uptake of Fe(+) plants was estimated. In the second trial, the rhizosphere pH of plants grown in an alkaline soil (pH in water = 8.3) was measured by a microelectrode. With the only exception of pears OH × F51 and A28, whose IRC was similar in Fe(+) and Fe(–) plants, the Fe-deficiency stress caused a significant decrease of the IRC. Among the Fe(–) plants, the two pear OH × F51 and A28 had higher IRC than the quince rootstocks and the cultivar Abbé F. When plants were pretreated with Fe, IRC was highest in the P. communis rootstocks (more than 50 nmol Fe2+/g fresh weight per h), intermediate in the own-rooted cultivars, and lowest in the quinces (&lt;15 nmol Fe2+/g fresh weight per h). Fe uptake proved to be linearly and positively correlated with root Fe-reducing capacity (r = 0.91***). Rhizosphere pH, averaged over the first 2 cm from root tips, was highest in quince MC (7.2), intermediate in the other two quinces and in the cultivar Abbé F. (6.2–6.6) and lowest in the pear rootstocks and in the cultivar Bartlett (5.2–5.5). The results indicate that roots of pear and quinces do not increase their ability to reduce the iron under Fe-deficiency stress. The genotypical differential tolerance to iron chlorosis likely reflects differences in the standard reductase system and in the capacity of lowering the pH at soil/root interface. The determination of the root IRC appears very promising as a screening technique for selecting efficient Fe-uptake rootstocks.