Concepts for understanding fruit trees

This book presents a clear set of integrative concepts for understanding the overall physiology and growth of temperate deciduous fruit trees. The emphasis is on overarching principles rather than detailed descriptions of tree physiology or difference among numerous species of fruit trees. Although the focus is on deciduous fruit trees, many aspects apply to evergreen fruit trees and trees that grow naturally in unmanaged situations.

Understanding the long-term storage sink.

Similar to short-term starch storage in the chloroplasts of the leaves that serves to buffer growth of organs from carbohydrate shortages due to diurnal patterns of photosynthesis related to daily patterns of light and darkness, trees also have long-term storage capacity to enable them to supply the minimal respiratory needs of tissues during the winter and resume growth in the spring when trees are still leafless. This long-term storage of carbohydrates and some minerals occurs primarily in the phloem and xylem tissue of the branches, trunk and roots. While active phloem tissue has higher concentrations of stored carbohydrates than xylem tissue, the mass of active xylem storage tissue is many times the mass of the active phloem tissue. Thus, xylem tissue comprises the largest storage compartment of temperate deciduous fruit trees. This chapter deals with understanding the long-term storage sink in fruit trees.

Revealing the Genetic Components Responsible for the Unique Photosynthetic Stem Capability of the Wild Almond Prunus arabica (Olivier) Meikle

Almond [Prunus dulcis (Mill.) D. A. Webb] is a major deciduous fruit tree crop worldwide. During dormancy, under warmer temperatures and inadequate chilling hours, the plant metabolic activity increases and may lead to carbohydrate deficiency. Prunus arabica (Olivier) Meikle is a bushy wild almond species known for its green, unbarked stem, which stays green even during the dormancy period. Our study revealed that P. arabica green stems assimilate significantly high rates of CO2 during the winter as compared to P. dulcis cv. Um el Fahem (U.E.F.) and may improve carbohydrate status throughout dormancy. To uncover the genetic inheritance and mechanism behind the P. arabica stem photosynthetic capability (SPC), a segregated F1 population was generated by crossing P. arabica to U.E.F. Both parent’s whole genome was sequenced, and SNP calling identified 4,887 informative SNPs for genotyping. A robust genetic map for U.E.F. and P. arabica was constructed (971 and 571 markers, respectively). QTL mapping and association study for the SPC phenotype revealed major QTL [log of odd (LOD) = 20.8] on chromosome 7 and another minor but significant QTL on chromosome 1 (LOD = 3.9). As expected, the P. arabica allele in the current loci significantly increased the SPC phenotype. Finally, a list of 64 candidate genes was generated. This work sets the stage for future research to investigate the mechanism regulating the SPC trait, how it affects the tree’s physiology, and its importance for breeding new cultivars better adapted to high winter temperatures.

Hepatoprotective activity of Flacourtia jangomas (Lour.) Raeuschleaves and fruit methanolic extract on paracetamol-induced hepatotoxicity in HepG2 Cells

Introduction and Aim: Plants have become the current focus of research in treating the various diseases and ailments. Flacourtia jangomas (Lour.) Raeusch belongs to the familySalicaceae. Itis a small deciduous fruit tree having immense nutritional and medicinal significance. Different parts of the plant are pharmaceutically used forcuring various ailments. In this study, we investigated the hepatoprotective activity of Flacourtia jangomas (Lour.) Raeusch leaves and fruit methanolic extract on Paracetamol induced HepG2 cell line. Methods: The cytotoxic and hepatoprotective properties were evaluated by measuring cell viability; activities of aspartate aminotransferase (AST), alanine aminotransferase (ALT), and lactate dehydrogenase (LDH); lipid peroxidation (malondialdehyde (MDA) levels). Results:The increased cell viability of 140.43± 4.07% and 133.93±3.20%was observed in HepG2 cells treated with methanolic extract of F. jangomas leaf and fruit extract respectively at 10µg/ml concentration and then decreased along with the rise of F. jangomas leaf and fruit extract concentrations. The level of LDH, ALT, AST and MDA decreased after F. jangomas leaf and fruit treatment compared to negative control. Conclusion: This study suggests that the methanolic Extract of F. jangomas (Lour.) Raeusch leaves(FJL)and fruit (FJF) shows hepatoprotective activity in Paracetamol induced HepG2 cell line by the decrease in AST and ALT activities and LDH and MDA level. Hence, it could be considered as a therapeutic agent in curing liver-related diseases.

Ethephon-Mediated Bloom Delay in Peach Is Associated With Alterations in Reactive Oxygen Species, Antioxidants, and Carbohydrate Metabolism During Dormancy

Ethephon (ET) is an ethylene-based plant growth regulator (PGR) that has demonstrated greater efficacy in delaying bloom in deciduous fruit species. However, the underlying mechanisms by which ET modulates dormancy and flowering time remain obscure. This study aimed to delineate the ET-mediated modulations of reactive oxygen species (ROS), antioxidants, and carbohydrate metabolism in relation to chilling and heat requirements of “Redhaven” peach trees during dormancy. Peach trees were treated with ethephon (500ppm) in the fall (at 50% leaf fall), and floral buds were collected at regular intervals of chilling hours (CH) and growing degree hours (GDH). In the control trees, hydrogen peroxide (H2O2) levels peaked at the endodormancy release and declined thereafter; a pattern that has been ascertained in other deciduous fruit trees. However, H2O2 levels were higher and sustained for a more extended period than control in the ET-treated trees. ET also increased the activity of ROS generating (e.g., NADPH-oxidase; superoxide dismutase) and scavenging (e.g., catalase, CAT; glutathione peroxidase) enzymes during endodormancy. However, CAT activity dropped significantly just before the bud burst in the ET-treated trees. In addition, ET affected the accumulation profiles of starch and soluble sugars (hexose and sucrose); significantly reducing the sucrose and glucose levels and increasing starch levels during endodormancy. However, our study concluded that variations in ROS levels and antioxidation pathways, rather than carbohydrate metabolism, could explain the differences in bloom time between ET-treated and -untreated trees. The present study also revealed several important bud dormancy controlling factors that are subject to modulation by ethephon. These factors can serve as potential targets for developing PGRs to manipulate bloom dates in stone fruits to avoid the ever-increasing threat of spring frosts.

The Mycobiota of High Altitude Pear Orchards Soil in Colombia

In Colombia, the cultivation of deciduous fruit trees such as pear is expanding for socio-economic reasons and is becoming more and more important for the local population. Since organized cultivation is slowly replacing sustenance cultivation, scientific information on the present agro-environment is needed to proceed in this change in an organic and environmentally friendly way. In particular, this study is an accurate description of the mycobiota present in the bulk soil of two different high altitude pear orchards in the Colombian Andes. The metabarcoding of soil samples allowed an in-depth analysis of the whole fungal community. The fungal assemblage was generally dominated by Ascomycota and secondly by Mortierellomycota. As observed in other studies in Colombia, the genus Mortierella was found to be especially abundant. The soil of the different pear orchards appeared to host quite different fungal communities according to the soil physico-chemical properties. The common mycobiota contained 35 fungal species, including several species of Mortierella, Humicola, Solicoccozyma and Exophiala. Moreover, most of the identified fungal species (79%) were recorded for the first time in Colombian soils, thus adding important information on soil biodiversity regarding both Colombia and pear orchards.

Revealing the genetic components responsible for the unique photosynthetic stem capability of the wild almond Prunus arabica (Olivier) Meikle

Almond (Prunus dulcis (Mill.) D. A. Webb) is a major deciduous fruit tree crop worldwide. During dormancy, under warmer temperatures and inadequate chilling hours, the plant metabolic activity increases and may lead to carbohydrate deficiency. Prunus arabica (Olivier) Meikle is a bushy wild almond species known for its green, un-barked stem, which stays green even during the dormancy period. Our study revealed that P. arabica green stems assimilate significantly high rates of CO2 during the winter as compared to P. dulcis cv. Um el Fahem (U.E.F), and may improve carbohydrate status throughout dormancy. To uncover the genetic inheritance and mechanism behind the P. arabicaStem Photosynthetic Capability (SPC), a segregated F1 population was generated by crossing P. arabica to U.E.F. Both parent’s whole genome was sequenced, and a single nucleotide polymorphism (SNP) calling identified 4,887 informative SNPs for genotyping. A robust genetic map for U.E.F and P. arabica was constructed (971 and 571 markers, respectively). QTL mapping and association study for the SPC phenotype revealed major QTL (log of odd (LOD)=20.8) on chromosome 7, and another minor but significant QTL on chromosome 1 (LOD=3.9). Finally, a list of 73 candidate genes was generated. This work sets the stage for future research to investigate the mechanism regulating the SPC trait, how it affects the tree’s physiology, and its importance for breeding new cultivars better adapted to high winter temperatures.

Pruning Wastes From Fruit Trees as a Substrate for Pleurotus ostreatus

Plant material obtained by pruning and production of deciduous fruit trees was evaluated as substrates for the production of the oyster mushroom, Pleurotus ostreatus . Lignified branches and stems from peach, apple, and pear trees were processed using a ripping machine to reduce the size of chips and to optimize disinfection. A completely randomized experimental design was proposed with six treatments (novel substrates) and one absolute control (100% hay substrate). Morphological variables such as thickness and diameter of the pileus, stipe length were assessed, as well as production variables (sprouting, fresh weight, and biological efficiency) and bromatological analysis (ash, ethereal extract, crude fiber, and crude protein). Apart from the 100%-hay substrate, biological efficiency ranged between 27% (100% apple tree as the substrate) and 140% (50% hay + 50% peach tree as the substrate). According to morphological analysis, the highest diameters were recorded from mixed substrates (50% hay + 50% wood), and a highly significant positive correlation was found between diameter and stipe length. Morphological parameters were not significantly correlated with biological efficiency. Analysis of biological efficiency confirmed that mixed substrates clustered together with 100%-wood substrates. Bromatological analysis showed that the mixed substrate (50% hay + 50% pear tree) had the highest protein content among the novel tested substrates. Bromatological parameters were not significantly correlated with biological efficiency. In conclusion, pruning residues from fruit trees can be valuable by using them as substrates for the cultivation of P. ostreatus . Production is quantitatively competitive with that using hay, on the condition that wood is mixed with hay.

Bud endodormancy in deciduous fruit trees: advances and prospects

Bud endodormancy is a complex physiological process that is indispensable for the survival, growth, and development of deciduous perennial plants. The timely release of endodormancy is essential for flowering and fruit production of deciduous fruit trees. A better understanding of the mechanism of endodormancy will be of great help in the artificial regulation of endodormancy to cope with climate change and in creating new cultivars with different chilling requirements. Studies in poplar have clarified the mechanism of vegetative bud endodormancy, but the endodormancy of floral buds in fruit trees needs further study. In this review, we focus on the molecular regulation of endodormancy induction, maintenance and release in floral buds of deciduous fruit trees. We also describe recent advances in quantitative trait loci analysis of chilling requirements in fruit trees. We discuss phytohormones, epigenetic regulation, and the detailed molecular network controlling endodormancy, centered on SHORT VEGETATIVE PHASE (SVP) and Dormancy-associated MADS-box (DAM) genes during endodormancy maintenance and release. Combining previous studies and our observations, we propose a regulatory model for bud endodormancy and offer some perspectives for the future.

LEAF AND FRUIT CHARACTERISTICS AND GENETIC DIVERSITY OF WILD FRUIT Cerasus prostrata GENOTYPES COLLECTED FROM THE CENTRAL ANATOLIA, TURKEY

Cerasus prostrata (Lab.) Ser. is quite widespread in some regions of Turkey. It is a wild and deciduous fruit species. The species is commonly encountered in Central Anatolia over the foothills of Erciyes Mountain. In this study, some fruit and leaf characteristics of 30 C. prostrata genotypes collected from the foothills of Erciyes Mountain were determined and genetic diversity among them was presented. Fruit weights of the genotypes varied between 0.66–0.23 g and fruit flesh ratios varied between 84.59–63.11%. Leaf width, leaf length and petiole lengths of the genotypes respectively varied between 1.61–0.68 cm; 4.02–1.82 cm and 0.60–0.28 cm. In genetic analyses, 17 ISSR primers were used and 115 bands were obtained. Of these bands, 98 were polymorphic. All genotypes were distinguished from each other. Relatively high variation was identified between the genotypes and similarity levels varied between 0.70–0.95. Current findings revealed significant information for the preservation and appraisal of C. prostrata. Further studies are recommended for breeding and protection of this species.