Dataset Information

Molecular Characterization and Stress Tolerance Evaluation of New Allotetraploid Somatic Hybrids Between Carrizo Citrange and Citrus macrophylla W. rootstocks.

ABSTRACT: Polyploidy is one of the main forces that drives the evolution of plants and provides great advantages for breeding. Somatic hybridization by protoplast fusion is used in citrus breeding programs. This method allows combining the whole parental genomes in a single genotype, adding complementary dominant characters, regardless of parental heterozygosity. It also contributes to surpass limitations imposed by reproductive biology and quickly generates progenies that combine the required traits. Two allotetraploid somatic hybrids recovered from the citrus rootstocks-Citrus macrophylla (CM) and Carrizo citrange (CC)-were characterized for morphology, genome composition using molecular markers (SNP, SSR, and InDel), and their tolerance to iron chlorosis, salinity, and Citrus tristeza virus (CTV). Both hybrids combine the whole parental genomes even though the loss of parental alleles was detected in most linkage groups. Mitochondrial genome was inherited from CM in both the hybrids, whereas recombination was observed for chloroplastic genome. Thus, somatic hybrids differ from each other in their genome composition, indicating that losses and rearrangements occurred during the fusion process. Both inherited the tolerance to stem pitting caused by CTV from CC, are tolerant to iron chlorosis such as CM, and have a higher tolerance to salinity than the sensitive CC. These hybrids have potential as improved rootstocks to grow citrus in areas with calcareous and saline soils where CTV is present, such as the Mediterranean region. The provided knowledge on the effects of somatic hybridization on the genome composition, anatomy, and physiology of citrus rootstocks will be key for breeding programs that aim to address current and future needs of the citrus industry.

SUBMITTER: Ruiz M

PROVIDER: S-EPMC6085489 | biostudies-literature | 2018

REPOSITORIES: biostudies-literature

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Publications

Molecular Characterization and Stress Tolerance Evaluation of New Allotetraploid Somatic Hybrids Between Carrizo Citrange and <i>Citrus macrophylla</i> W. rootstocks.

Ruiz Marta M Pensabene-Bellavia Giovanni G Quiñones Ana A García-Lor Andrés A Morillon Raphaël R Ollitrault Patrick P Primo-Millo Eduardo E Navarro Luis L Aleza Pablo P

Frontiers in plant science 20180803

Polyploidy is one of the main forces that drives the evolution of plants and provides great advantages for breeding. Somatic hybridization by protoplast fusion is used in citrus breeding programs. This method allows combining the whole parental genomes in a single genotype, adding complementary dominant characters, regardless of parental heterozygosity. It also contributes to surpass limitations imposed by reproductive biology and quickly generates progenies that combine the required traits. Two ...[more]

PMID: 30123223

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Project description:The deficit of oxygen in plants is a frequent phenomenon in nature. The main causes may be due to flooding or excessive irrigation or to an excess of aerobic microflora in the soil. The Intergovernmental Panel on Climate Change (IPCC) reported that the anthropogenically induced change of world climate increases the frequency of heavy precipitation and tropical cyclone activity. This is likely to engender more frequent flooding events in river flood plains and arable farmland, particularly affecting the world’s poorest farmers. The stress caused by lack of oxygen in plants mainly produces a reduction of the respiration, and then a low energy production and accumulation of toxic compounds of anaerobic metabolism. To alleviate this problem plants have developed morphological and metabolic adaptations, the main of which include the induction of anaerobic and fermentative pathways. In the present study we used a Combimatrix platform, made up of around 8,000 ESTs of roots isolated in citrus and its rootstocks. The chip was hybridized with RNA wild type Carrizo citrange roots and a transgenic line highly expressing a transcription factor involved in the response to the deficiency of oxygen in Oryza sativa. The aim of the work consists in the study of the up and down expressed genes in wild type and transgenic lines subjected and not to anaerobiosis, in order to understand the mechanisms that are activated under anoxia. In general, the hybridization of the chip has led to the activation of 492 genes, of which 28.95% is involved in redox processes, 28.41% in the response to stress, 18.28% in response to chemical stimuli. The up and down-regulation of differentially expressed transcripts in response to oxygen deficiency were confirmed through real-time RT-PCR The results obtained showed the activation of main genes involved in the glycolytic and fermentative pathways, such as pyruvate decarboxylase, alcohol dehydrogenase and sucrose synthase. In transgenic plants of Carrizo the response to oxygen deficit appears to be more pronounced, therefore genes of glycolytic, fermentation and pentose phosphate pathway are activated.

Project description:Citrus crops have a long history of cultivation as grafted trees on selected rootstock cultivars, but all current rootstocks have significant limitations and traditional methods of rootstock breeding take at least 2-3 decades to develop and field test new rootstocks. Citrus production in the United States, and other parts of the world, is impaired by a wide range of biotic and abiotic problems, with especially severe damage caused by the disease huanglongbing (HLB) associated with Candidatus Liberibacter asiaticus. All major commercial citrus scion cultivars are damaged by HLB, but tree tolerance is significantly improved by some rootstocks. To overcome these challenges, the USDA citrus breeding program has implemented a multi-pronged strategy for rootstock breeding that expands the diversity of germplasm utilized in rootstock breeding, significantly increases the number of new hybrids evaluated concurrently, and greatly reduces the time from cross to potential cultivar release. We describe the key components and methodologies of this new strategy, termed "SuperSour," along with reference to the historical favorite rootstock sour orange (Citrus aurantium), and previous methods employed in citrus rootstock breeding. Rootstock propagation by cuttings and tissue culture is one key to the new strategy, and by avoiding the need for nucellar seeds, eliminates the 6- to 15-year delay in testing while waiting for new hybrids to fruit. In addition, avoiding selection of parents and progeny based on nucellar polyembryony vastly expands the potential genepool for use in rootstock improvement. Fifteen new field trials with more than 350 new hybrid rootstocks have been established under the SuperSour strategy in the last 8 years. Detailed multi-year performance data from the trials will be used to identify superior rootstocks for commercial release, and to map important traits and develop molecular markers for the next generation of rootstock development. Results from two of these multi-year replicated field trials with sweet orange scion are presented to illustrate performance of 97 new hybrid rootstocks relative to four commercial rootstocks. Through the first 7 years in the field with endemic HLB, many of the new SuperSour hybrid rootstocks exhibit greatly superior fruit yield, yield efficiency, canopy health, and fruit quality, as compared with the standard rootstocks included in the trials.

Dataset Information

Molecular Characterization and Stress Tolerance Evaluation of New Allotetraploid Somatic Hybrids Between Carrizo Citrange and Citrus macrophylla W. rootstocks.

Publications

Molecular Characterization and Stress Tolerance Evaluation of New Allotetraploid Somatic Hybrids Between Carrizo Citrange and <i>Citrus macrophylla</i> W. rootstocks.

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