Genome-Wide SNP Markers Accelerate Perennial Forest Tree Breeding Rate for Disease Resistance through Marker-Assisted and Genome-Wide Selection.

The ecological and economic importance of forest trees is evident and their survival is necessary to provide the raw materials needed for wood and paper industries, to preserve the diversity of associated animal and plant species, to protect water and soil, and to regulate climate. Forest trees are threatened by anthropogenic factors and biotic and abiotic stresses. Various diseases, including those caused by fungal pathogens, are one of the main threats to forest trees that lead to their dieback. Genomics and transcriptomics studies using next-generation sequencing (NGS) methods can help reveal the architecture of resistance to various diseases and exploit natural genetic diversity to select elite genotypes with high resistance to diseases. In the last two decades, QTL mapping studies led to the identification of QTLs related to disease resistance traits and gene families and transcription factors involved in them, including NB-LRR, WRKY, bZIP and MYB. On the other hand, due to the limitation of recombination events in traditional QTL mapping in families derived from bi-parental crosses, genome-wide association studies (GWAS) that are based on linkage disequilibrium (LD) in unstructured populations overcame these limitations and were able to narrow down QTLs to single genes through genotyping of many individuals using high-throughput markers. Association and QTL mapping studies, by identifying markers closely linked to the target trait, are the prerequisite for marker-assisted selection (MAS) and reduce the breeding period in perennial forest trees. The genomic selection (GS) method uses the information on all markers across the whole genome, regardless of their significance for development of a predictive model for the performance of individuals in relation to a specific trait. GS studies also increase gain per unit of time and dramatically increase the speed of breeding programs. This review article is focused on the progress achieved in the field of dissecting forest tree disease resistance architecture through GWAS and QTL mapping studies. Finally, the merit of methods such as GS in accelerating forest tree breeding programs is also discussed.

Phytochemical profile of fennel essential oils and possible applications for natural antioxidant and controlling Convolvulus arvensis L.

The natural compounds such as essential oils are getting more attention due to their potential usage in pharmaceuticals and possibly as natural herbicides. This study was conducted to identify the chemical compositions of essential oils from Foeniculum vulgare Mill. populations collected from different regions of Iran, Turkey, and Germany, and their antioxidant (DPPH·, ABTS·+ and reducing power methods) and phytotoxic activity (against Convolvulus arvensis L.). The results exhibited a significant variation in essential oils content (1.74-2.97%). The main compounds in essential oils were trans-anethole (15.23%-90.11%), estragole (4.00-63.72%), fenchone (0.03-12.62%) and limonene (1.05-13.04%). The results revealed that the essential oils have considerable antioxidant (IC50 values in the range of 11.83-36.90 mg mL-1 in DPPH, 7.65-20.13 mg mL-1 in ABTS·+ and EC50 values in the range of 3.65-15.24 mg mL-1 in reducing power assay) and phytotoxic activity. The results of this study can help in the development of natural antioxidants and herbicides.

Metabolically engineered rice biomass and grain using genes associated with lipid pathway show high level of oil content.

Increasing lipid content using metabolic engineering methods in different parts of plant, including, leaves and stem can be considered as an innovative platform for achieving more energy and biofuel in more green habits. Two key enzymes, including, diacylglycerol acyltransferase (DGAT) and phospholipid:diacylglycerol acyltransferase (PDAT) catalyze the final step of TAG assembly. WRINKLED1 (WRI1) is one of the important transcription factors which regulate the fatty acid biosynthesis network and TAG accumulation by balancing carbon flux between carbohydrates and lipids. In addition, oleosin encoding gene (OLE) can protect TAGs from degradation by packing into oil bodies. In the current study, four important genes involved in TAG assembly and protection (i.e., AtDGAT1 and AtPDAT, AtWRI1, and AtOle) were overexpressed under a constitutive promoter in rice crop. TAG content of transgenic seeds increased significantly (P ≤ 0.05) by 26% in compared with those of control plants. Oleic and palmitic acid contents were significantly increased by 28% (from 32 to 41) and 27% (11 to 14) in seeds of transgenic plants in compared with controls, respectively. Our results showed an increase in the total grain and leaf oil contents by 70% (from 1.1 to 1.87%) and 22.5% (from 1.88 to 2.3%) in the metabolically engineered lines, respectively. This is the first report of transformation in rice for enhancing oil content and energy density in its seeds and vegetative parts. Such metabolically engineered crops would be cultivated for production much more oils in seeds and straw for food and biodiesel consequently.

Exogenous ß-aminobutyric acid application attenuates Aspergillus decay, minimizes aflatoxin B1 accumulation, and maintains nutritional quality in fresh-in-hull pistachio kernels.

BACKGROUND: Pistachio fruits suffer from postharvest decay, caused by Aspergillus flavus. This results in aflatoxin B1 (AFB1 ) accumulation in kernels, which is hazardous for human health due to its carcinogenic activity. In this study, the mechanism used by exogenous ß-aminobutyric acid (BABA) treatment for attenuating Aspergillus decay, minimizing aflatoxin B1 (AFB1 ) accumulation, and maintaining nutritional quality in fresh-in-hull pistachio kernels, infected by A. flavus during storage at 25 °C for 18 days, was investigated. RESULT: Results of an in vivo assay showed that the spore germination and germ tube elongation of A. flavus was repressed by BABA treatment at 7.5 mM. Aspergillus decay accompanied by AFB1 accumulation was also minimized in fresh-in-hull pistachio kernels treated with BABA at 7.5 mM and infected by A. flavus. Fresh-in-hull pistachio kernels, infected by A. flavus, treated with BABA at 7.5 mM, also exhibited higher phenol and flavonoid accumulation and 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging capacity accompanied by higher phenylalanine ammonia lyase (PAL) enzyme activity. CONCLUSION: Promoting phenylpropanoid pathway activity with higher PAL enzyme activity in fresh-in-hull pistachio kernels treated with BABA may not only reduce Aspergillus decay in kernels by cell wall fortification but also may be favorable for maintaining the kernels' nutritional quality through its effects on ROS scavenging capacity. As oxidative stress, represented by ROS accumulation, is responsible for A. flavus growth and AFB1 accumulation, higher phenol and flavonoid accumulation in fresh-in-hull pistachio kernels treated with BABA may be beneficial for attenuating Aspergillus decay and minimizing AFB1 accumulation. © 2019 Society of Chemical Industry.