Trifolium subterraneum cover cropping for improving the nutritional status of a Mediterranean apricot orchard

BACKGROUND

The utilization of Trifolium subterraneum L. cover crops may represent an innovative and efficient option in low-input and organic farming, especially in Mediterranean agroecosystems where low and irregular rainfall require frequent soil tillage and use of herbicides to reduce moisture losses and weed competitiveness. Since imbalances of soil macro- and micro-nutrients due to cover cropping establishment could be responsible for numerous problems in specialized orchards, such as disturbances in the normal tree growth and quality of fruits, the objective of this study was to investigate, the cumulative effects of a 3-years established T. subterraneum cover cropping, compared with a spontaneous flora and a conventional management (as a control), on the levels of mineral nutrients in the apricot leaves and fruits.

RESULTS

Our findings indicated that T. subterraneum cover cropping tended to stimulate higher leaf macro- and micro-nutrients content than conventional management and flora spontaneous cover cropping. In addition, the presence of T. subterraneum cover cropping, especially with the incorporation of dead mulches into the soil, increased the content of potassium (K), nitrogen (N), calcium (Ca), iron (Fe) and manganese (Mn) in apricot fruits.

CONCLUSION

Taking also into account the effects of T. subterraneum cover cropping on both the reduction of soil weed and enhancement of bacteria communities involved in the soil N-cycle, we may suggest its application in Mediterranean orchards as an eco-friendly alternative to synthetic herbicides for weed control and mineral N fertilizers, while enhancing the apricot tree nutritional status and fruit quality. © 2020 Society of Chemical Industry.

Trifolium subterraneum cover cropping for improving the nutritional status of a Mediterranean apricot orchard

BACKGROUND

The utilization of Trifolium subterraneum L. cover crops may represent an innovative and efficient option in low-input and organic farming, especially in Mediterranean agroecosystems where low and irregular rainfall require frequent soil tillage and use of herbicides to reduce moisture losses and weed competitiveness. Since imbalances of soil macro- and micro-nutrients due to cover cropping establishment could be responsible for numerous problems in specialized orchards, such as disturbances in the normal tree growth and quality of fruits, the objective of this study was to investigate, the cumulative effects of a 3-years established T. subterraneum cover cropping, compared with a spontaneous flora and a conventional management (as a control), on the levels of mineral nutrients in the apricot leaves and fruits.

RESULTS

Our findings indicated that T. subterraneum cover cropping tended to stimulate higher leaf macro- and micro-nutrients content than conventional management and flora spontaneous cover cropping. In addition, the presence of T. subterraneum cover cropping, especially with the incorporation of dead mulches into the soil, increased the content of potassium (K), nitrogen (N), calcium (Ca), iron (Fe) and manganese (Mn) in apricot fruits.

CONCLUSION

Taking also into account the effects of T. subterraneum cover cropping on both the reduction of soil weed and enhancement of bacteria communities involved in the soil N-cycle, we may suggest its application in Mediterranean orchards as an eco-friendly alternative to synthetic herbicides for weed control and mineral N fertilizers, while enhancing the apricot tree nutritional status and fruit quality. © 2020 Society of Chemical Industry.

Population genomics of apricots unravels domestication history and adaptive events

Among crop fruit trees, the apricot (Prunus armeniaca) provides an excellent model to study divergence and adaptation processes. Here, we obtain nearly 600 Armeniaca apricot genomes and four high-quality assemblies anchored on genetic maps. Chinese and European apricots form two differentiated gene pools with high genetic diversity, resulting from independent domestication events from distinct wild Central Asian populations, and with subsequent gene flow. A relatively low proportion of the genome is affected by selection. Different genomic regions show footprints of selection in European and Chinese cultivated apricots, despite convergent phenotypic traits, with predicted functions in both groups involved in the perennial life cycle, fruit quality and disease resistance. Selection footprints appear more abundant in European apricots, with a hotspot on chromosome 4, while admixture is more pervasive in Chinese cultivated apricots. Our study provides clues to the biology of selected traits and targets for fruit tree research and breeding.

Meta-analysis of RNA-Seq studies reveals genes with dominant functions during flower bud endo- to eco-dormancy transition in Prunus species

In deciduous fruit trees, entrance into dormancy occurs in later summer/fall, concomitantly with the shortening of day length and decrease in temperature. Dormancy can be divided into endodormancy, ecodormancy and paradormancy. In Prunus species flower buds, entrance into the dormant stage occurs when the apical meristem is partially differentiated; during dormancy, flower verticils continue their growth and differentiation. Each species and/or cultivar requires exposure to low winter temperature followed by warm temperatures, quantified as chilling and heat requirements, to remove the physiological blocks that inhibit budburst. A comprehensive meta-analysis of transcriptomic studies on flower buds of sweet cherry, apricot and peach was conducted, by investigating the gene expression profiles during bud endo- to ecodormancy transition in genotypes differing in chilling requirements. Conserved and distinctive expression patterns were observed, allowing the identification of gene specifically associated with endodormancy or ecodormancy. In addition to the MADS-box transcription factor family, hormone-related genes, chromatin modifiers, macro- and micro-gametogenesis related genes and environmental integrators, were identified as novel biomarker candidates for flower bud development during winter in stone fruits. In parallel, flower bud differentiation processes were associated to dormancy progression and termination and to environmental factors triggering dormancy phase-specific gene expression.

Component Profiling in Agricultural Applications Using an Adjustable Acupuncture Needle for Sheath-Flow Probe Electrospray Ionization/Mass Spectrometry

In previous work, probe electrospray ionization/mass spectrometry (PESI/MS) and sheath-flow probe electrospray ionization/mass spectrometry (sfPESI/MS) were reported for the rapid and minimally invasive analysis of food. In this work, a modified version of sfPESI will be reported. The sample surface was pricked with an acupuncture needle inserted in the sfPESI probe that protruded from the terminus of the tip by 5 mm. The invasion depth of the needle into the sample was ∼1 mm. After sampling, the needle was retracted into the solvent-preloaded capillary with a protrusion length of 0.1-0.2 mm from the tip. A mass spectrum of the sample captured on the needle was obtained by applying a high voltage to the needle. This method could be applicable to profiling analyses of plants with the epicuticular wax covering on the surfaces that are difficult to analyze by sf-PESI. The on-site mass spectrometric analysis for a growing apricot in the field was performed to monitor the developing stage of the fruit.

Comparative transcriptome profiling and morphology provide insights into endocarp cleaving of apricot cultivar (Prunus armeniaca L.)

BACKGROUND

A complete and hardened endocarp is a typical trait of drupe fruits. However, the 'Liehe' (LE) apricot cultivar has a thin, soft, cleavable endocarp that represents 60.39% and 63.76% of the thickness and lignin content, respectively, of the 'Jinxihong' (JG) apricot (with normal hardened-endocarp). To understand the molecular mechanisms behind the LE apricot phenotype, comparative transcriptomes of Prunus armeniaca L. were sequenced using Illumina HiSeq™ 2500.

RESULTS

In this study, we identified 63,170 unigenes including 15,469 genes >1000 bp and 25,356 genes with Gene Function annotation. Pathway enrichment and expression patterns were used to characterize differentially expression genes. The DEGs encoding key enzymes involved in phenylpropanoid biosynthesis were significantly down-regulated in LE apricot. For example, CAD gene expression levels, encoding cinnamyl alcohol dehydrogenase, were only 1.3%, 0.7%, 0.2% and 2.7% in LE apricot compared with JG cultivar at 15, 21, 30, 49 days after full bloom (DAFB). Furthermore, transcription factors regulating secondary wall and lignin biosynthesis were identified. Especially for SECONDARY WALL THICKENING PROMOTING FACTOR 1 (NST 1), its expression levels in LE apricot were merely 2.8% and 9.3% compared with JG cultivar at 15 and 21 DAFB, respectively.

CONCLUSIONS

Our comparative transcriptome analysis was used to understand the molecular mechanisms underlie the endocarp-cleaving phenotype in LE apricot. This new apricot genomic resource and the candidate genes provide a useful reference for further investigating the lignification during development of apricot endocarp. Transcription factors such as NST1 may regulate genes involved in phenylpropanoid pathway and affect development and lignification of the endocarp.