Rootstock Breeding for Abiotic Stress Tolerance in Citrus

Citrus species are the most widely produced fruit crops in the world. Citrus fruits are mainly produced in coastal areas in several countries as well as Mediterranean region, and production in these regions is affected by both biotic and abiotic stresses, including drought, extreme temperature, salinity, citrus canker, citrus tristeza virus, citrus greening, and others. The use of rootstocks in fruit production includes not only stronger resistance against pathogens but also a higher tolerance to abiotic stress conditions such as salinity, heavy metals, nutrient stress, water stress, and alkalinity. There is extensive genetic diversity in citrus which provides several materials to be used as rootstocks against abiotic stress. In this work, we tried to provide an overview of the abiotic stresses in citrus by combining literature with our studies, role of citrus rootstocks commercially used against abiotic stresses and rootstock breeding in citrus

Genetic Diversity in Citrus

WOS: 000403834500012

Genetic Diversity and Breeding of Persimmon

The genus Diospyros, which is distributed in tropical and subtropical regions of the world, contains hundreds of plant species. However, four species of them have commercial importance. D. kaki Thunb. is the most widely cultivated species of the Diospyros genus. Persimmon (D. kaki Thunb.) is grown in many parts of the world that display subtropical climate conditions. In recent years, the cultivation of persimmon has found renewed interest in various countries of the Mediterranean basin. In China (which is the origin of persimmon) and in Japan and Korea (where it is grown widely), persimmons were selected from some well-known old varieties. Recently in countries such as Italy, Spain, USA, Brazil, Turkey and Israel, persimmons were selected from new cultivars. Currently China, Japan and Korea have the big persimmon germplasm collections with a large number of varieties and other Diospyros species. Also, Italy, Spain, USA, Brazil, Turkey, Israel, Azerbaijan, Uzbekistan and Pakistan have constituted the germplasms by high commercial value cultivars and/or local varieties. In this chapter, we tried to provide an overview of the genetic diversity and breeding of persimmon by combining literature with our studies

Genetic relationships of some Citrus genotypes based on the candidate iron chlorosis genes

Iron is one of the most important elements in plant mineral nutrition. Fe deficiency is a critical abiotic stress factor for Mediterranean citriculture; the development of marker-assisted selection for this trait would greatly enhance rootstock breeding. In this study, DNA sequencing and single-stranded conformation polymorphism (SSCP) analyses were performed to determine the allelic diversity of genes associated with tolerance to iron chlorosis in citrus. Two candidate iron chlorosis tolerance genes were selected from existing Citrus EST databases and Arabidopsis thaliana genome databases. Ferritin-3 chloroplast precursor and putative membrane transporter candidate gene sequences were used to define primers in conserved regions. Six citrus genotypes from the basic taxon of Citrus were used to identify polymorphic regions in the genes. Direct sequencing of the amplified DNA fragments from the candidate genes was performed, and single nucleotide polymorphisms (SNPs) and insertions/deletions (indels) were identified after sequence alignment. Based on the DNA sequencing analysis, a total of 6840 nucleotides of DNA were sequenced to identify SNPs and indels. In total, 263 SNPs and 15 indels were identified for both genes. We detected 38.45 SNPs and 2.19 indels for each 1000 b on average from the DNA sequencing results. New primers were designed in conserved areas flanking polymorphic ones for SSCP analysis. SSCP-PCR analysis was performed with 25 citrus genotypes. The neighbor-joining method was used for cluster analysis. Trifoliate genotypes and their hybrids (known to be sensitive to iron chlorosis) clustered together, whereas genotypes tolerant to iron chlorosis were more spread out on the dendrogram. Mandarins also showed high diversity for both genes according to SSCP results. Differences were found among sour orange genotypes known to have differential tolerance behavior to iron chlorosis. (Résumé d'auteur

Effects of 2,4-DP- P (2,4-Dichlorophenoxypropionic Acid-P) Plant Growth Regulator on Fruit Size and Yield of Star Ruby Grapefruit (Citrus paradisi Osb.)

Star Ruby is the main grapefruit (Citrus paradisi) variety grown in Turkey; however, small fruit size is a common problem in ‘Star Ruby’ grapefruit. Fruit size is a decisive external quality parameter in citrus at the marketing of fresh citrus fruits. Fruit size can be enhanced by several techniques such as girdling and thinning. Various plant growth regulators are known to affect the growth and size of citrus fruit. The objective of the present study was to observe the effects of 2,4 dichlorophenoxypropionic acid-p (2,4-DP-P) on the fruit size, yield and quality of Star Ruby from 20-year-old trees budded on sour orange rootstock in Adana, Turkey in 2007. Four concentrations (50, 100, 150 and 300 ppm) of 2,4-DP-P were applied 8 weeks after anthesis during physiological fruit drop when the mean fruit diameter was 13-15 mm. The results indicated that the application of 2,4-DP-P increased the fruit size of Star Ruby grapefruit without reducing yield. The application had a significant effect on fruit yield except for trees treated with 50 ppm 2,4-DP-P. Compared with the control trees, applications of 2,4-DP-P increased the number of large, commercially valuable Star Ruby (>93 mm, 89-93 mm and 84-89 mm). No effects were determined on fruit internal quality parameters. Thus, the results of the present study revealed that 2,4-DP-P can be used to improve the fruit size of Star Ruby fruitlets during the June drop

THE USAGE OF AUXINS WITH VARIOUS CULTURAL TECHNIQUES TO INCREASE FRUIT SIZE IN STAR RUBY GRAPEFRUIT

WOS: 000413499500004Fruit size is a key parameter for quality and increases the profitability for export markets in citrus production in Turkey. Fruit size can be enhanced by several techniques such as girdling and thinning. Various plant growth regulators are known to affect the growth and size of citrus fruit. Thus the effects of synthetic auxin applications (2,4-DP and 3,5,6-TPA) at different physiological periods, girdling practices, pruning practices, foliar application of potassium and various combinations of these practices on the fruit size and yield, fruit retention rate, and leaf chlorophyll concentration and fluorescence of Star Ruby grapefruit cultivar were investigated. As a result of pomological observations, treatments had different effects on fruit size and yield. The highest yield per tree were determined in Maxim (3,5,6-TPA) and Citrimax (2,4-DP) (605.33 and 601.83 kg/tree) treatments. The highest fruit diameter was determined from foliar spray of K (83.25 mm) on leafs whereas the lowest was obtained from control samples with 78.96 mm. The highest leaf chlorophyll concentration was determined in the leaf treated with foliar spray of K.Cukurova University, Scientific Research Projects Coordinating OfficeCukurova University [CU-BAP-ZF2011YL12]Special thanks are due to the Cukurova University, Scientific Research Projects Coordinating Office (project CU-BAP-ZF2011YL12) for supporting the present study

The Effects of Local Sour Orange, Carrizo and Troyer Citrange Rootstocks on Carbohydrate Contents and Seasonal Changes in Leaves of Marsh Seedless Variety Grown in Antalya

WOS: 000279315000003In this study, it was intended to identify the most suitable rootstock X scion combination, taking into account the carbohydrate content of grapefruit leaves of Marsh Seedless, which is amongst important citrus varieties, in terms of our country and our region, hanging on Troyer and Carrizo citrange rootstocks and considered an alternative to sour orange. The trees, which were 18 years old at West Mediterranean Agricultural Research Institute, have been used as experiment material. The highest carbohydrates contents were found at trees on citrange rootstocks. When we look for seasonal changes, we determined that total carbohydrates, starch and carbohydrate/nitrogen (C/N) rate increases from spring to summer and decreases to fall; total sugar, reduced sugar and sucrose content decreases from spring to fall and increases to winter. As a result of our study, the highest total carbohydrates contents were found at trees on Carrizo citrange rootstocks. On the other hand, higher starch, total sugar, reduced sugar and sucrose were determined on citrange rootstocks