Project description:The vast majority of traditional almond varieties are self-incompatible and the level of variability of the species is very high, resulting in a highly heterozygosity genome. Therefore, information on the different haplotypes is particularly relevant to understand the genetic basis of trait variability in this species. However, although reference genomes for several almond varieties exist, none of them is phased and has genome information at the haplotype level. Here we present a phased assembly of genome of the almond cv. Texas. Our analysis shows that the “Texas” genome has a high degree of heterozygosity, both as SNPs, short indels, and structural variants (SV) level. Many of the SVs are due to heterozygous Transposable Element (TE) insertions, and in many cases they also contain genic sequences. In addition to the direct consequences of this genic variability on the presence/absence of genes, our results show that variants located close to genes tend to be associated with allele-specific gene expression (ASE), which highlights the importance of heterozygous SVs in almond.
Project description:A phased genome of the highly heterozygous 'Texas' almond uncovers patterns of allele-specific expression linked to heterozygous structural variants
Project description:The cultivated almond exhibits self-incompatibility of the gametophytic type regulated by the S-locus, and expressed in pistil (S-RNase) and in pollen (SFB protein). The aim of this study is to clarify the transcription pattern of these 2 S-genes and to identify additional components of the gametophytic self-incompatibility system in almond. With this aim, A2-198 (self compatible) and ITAP-1 (self incompatible) almond selections were used: RNA-seq of pistils of these two accessions both un-pollinated and pollinated with A2-198 pollen were carried out.
Project description:Almond is one of the most featured nut crops owing to its high nutritional value. However, due to three different waves of flower and fruitlet drop, fruit drop is a major concern for growers. In this study, we carried out a time-course transcriptome analysis to investigate gene expression difference between normal and abnormal fruitlet development. By de novo assembly analysis, we identified 33,577 unigenes and provided their functional annotations. In total, we identified 8,676 differentially expressed genes and observed the most apparent difference between normal and abnormal fruits at 12 and 17 day after flowering. Their biological functions were enriched in carbon metabolism, carbon fixation in photosynthetic organisms and plant hormone signal transduction. RT-qPCR validated the expression pattern of 15 representative genes, including glycosyltransferase like family 2, MYB39, IAA13, gibberellin-regulated protein 11-like and POD44, which confirmed the reliability of our transcriptome data. This study provides an insight into the association between abnormal fruit development and carbohydrate signaling from the early developmental stages and could be served as useful information for understanding the regulatory mechanism related to almond fruit drop.
Project description:Transposons played a major role in the diversification between the closely related almond (Prunus dulcis) and peach (P. persica) genomes: Results from the almond genome sequence.
Project description:Plum pox virus (PPV) causes the serious sharka disease in Prunus trees. Peach [P. persica (L.) Batsch] trees are severely affected by PPV and no definitive source of genetic resistance has been identified at this moment. Previous results showed, however, that PPV-resistant ‘Garrigues’ almond [P. dulcis (Mill.) D.A. Webb] was able to transfer its resistance to ‘GF305’ peach through grafting, preventing these trees from PPV infection and reducing symptomatology and viral load in PPV-infected plants. A recent study tried to identify genes responsible for this effect by studying mRNA expression through RNAseq data in peach and almond plants, before and after grafting, and before and after PPV infection. In this work, we used the same peach and almond samples, but focused the high-throughput analyses on small RNAs (sRNAs) expression. We studied massive sequencing data and found an interesting pattern of sRNAs overexpression linked to antiviral defense genes that suggested activation of these genes followed by downregulation to basal levels. We also discovered that ‘Garrigues’ almond plants were infected by different plant viruses that were transferred to peach plants. The large amounts of viral sRNAs found in grafted peaches indicated a strong RNA silencing antiviral response and led us to postulate that these plant viruses could be collaborating by cross-protection in the observed ‘Garrigues’ effect.
Project description:Transposons played a major role in the diversification between the closely related almond (Prunus dulcis) and peach (P. persica) genomes: Results from the almond genome sequence
Project description:Gametophytic self-incompatibility is the primary cause of low fruit set in almond. The mechanism of recognition that determines whether the gametophyte is successfully fertilized between pollen tube SCF (F-box-SSK1-Cul1-Rbx1) protein and pistil S-RNase protein during fertilization is unclear. In this study, the pistils of two almond cultivars 'Wanfeng' and 'Nonpareil' were used as the experimental materials after selfing- and nonselfing/cross-pollination, and pistils from the stamen-removed flowers were used as controls. We used fluorescence microscopy to observe the development of pollen tubes after pollination and 4-dimensional label-free quantitation (4D-LFQ) to detect the protein expression profiles of 'Wanfeng' and 'Nonpareil' pistils and in controls. The results showed that it took 24-36 h for the development of the pollen tube to 1/3 of the pistil, and a total of 7684 differentially accumulated proteins (DAPs) were identified in the pistil after pollinating 36 h, of which 7022 were quantifiable. The up- and down-regulation of the 12 differential protein expressions identified by parallel reaction monitoring (PRM) was the same as that identified by 4D-LFQ, with an average fold-change difference of 14.34%, a maximum of 31.37% and a minimum of 3.68%. Bioinformatics analysis based on the function of the differential proteins, including classification, enrichment, and clustering, identified RNA polymerases (4 DAPs), autophagy (3 DAPs), oxidative phosphorylation (3 DAPs), and homologous recombination (2 DAPs) pathways associated with the self-incompatibility process. The interaction between the serine/threonine kinase (MARK2) protein E3 ubiquitin ligase and the microtubule protein component microtubule-associated protein tau (MAPT/ACT) was found using the STRING database, which demonstrated the involvement of the MARK2 protein in the reaction of pollen tube recognition the nonself- and the self-S-RNase protein. It provides a new way to reveal the mechanism by which almond pollen tubes recognize the self and nonself S-RNase enzyme protein.