Physiological Changes and Transcriptomic Analysis throughout On-Tree Fruit Ripening Process in Persimmon (Diospyros kaki L.).

The involvement of effectors and transcriptional regulators in persimmon fruit maturation has been mostly approached by the literature under postharvest conditions. In order to elucidate the participation of these genes in the on-tree fruit maturation development, we have collected samples from seven persimmon germplasm accessions at different developmental stages until physiological maturation. This study has focused on the expression analysis of 13 genes involved in ethylene biosynthesis and response pathways, as well as the evolution of important agronomical traits such as skin colour, weight, and firmness. Results revealed different gene expression patterns, with genes up- and down-regulated during fruit development progression. A principal component analysis was performed to correlate gene expression with agronomical traits. The decreasing expression of the ethylene biosynthetic genes DkACO1, DkACO2, and DkACS2, in concordance with other sensing (DkERS1) and transduction genes (DkERF18), provides a molecular mechanism for the previously described high production of ethylene in immature detached fruits. On the other side, DkERF8 and DkERF16 are postulated to induce fruit softening and skin colour change during natural persimmon fruit ripening via DkXTH9 and DkPSY activation, respectively. This study provides valuable information for a better understanding of the ethylene signalling pathway and its regulation during on-tree fruit ripening in persimmon.

Insights of Phenolic Pathway in Fruits: Transcriptional and Metabolic Profiling in Apricot (Prunus armeniaca).

There is an increasing interest in polyphenols, plant secondary metabolites, in terms of fruit quality and diet, mainly due to their antioxidant effect. However, the identification of key gene enzymes and their roles in the phenylpropanoid pathway in temperate fruits species remains uncertain. Apricot (Prunus armeniaca) is a Mediterranean fruit with high diversity and fruit quality properties, being an excellent source of polyphenol compounds. For a better understanding of the phenolic pathway in these fruits, we selected a set of accessions with genetic-based differences in phenolic compounds accumulation. HPLC analysis of the main phenolic compounds and transcriptional analysis of the genes involved in key steps of the polyphenol network were carried out. Phenylalanine ammonia-lyase (PAL), dihydroflavonol-4-reductase (DFR) and flavonol synthase (FLS) were the key enzymes selected. Orthologous of the genes involved in transcription of these enzymes were identified in apricot: ParPAL1, ParPAL2, ParDFR, ParFLS1 and ParFLS2. Transcriptional data of the genes involved in those critical points and their relationships with the polyphenol compounds were analyzed. Higher expression of ParDFR and ParPAL2 has been associated with red-blushed accessions. Differences in expression between paralogues could be related to the presence of a BOXCOREDCPAL cis-acting element related to the genes involved in anthocyanin synthesis ParFLS2, ParDFR and ParPAL2.

Correction: A cross population between D. kaki and D. virginiana shows high variability for saline tolerance and improved salt stress tolerance.

[This corrects the article DOI: 10.1371/journal.pone.0229023.].

Intra and Inter-specific Variability of Salt Tolerance Mechanisms in Diospyros Genus.

Saline stress is one of most important problems that agriculture must face in the context of climate change. In the Mediterranean basin, one of the regions most affected, persimmon production can be compromised by this effect, due to the limited availability of salt tolerant rootstocks. Seedlings coming from four populations from the Diospyros genus have been exposed to salt stress in order to identify salt tolerance genotypes within these populations. Morphological, physiological, and transcriptomic approaches have revealed different mechanisms of tolerance among the population studied. An HKT1-like gene has been shown to have different root expression related to the salt tolerance phenotypes among and within populations. Additionally, we have observed differences in salt-responsive expression among PIP aquaporin genes. Genetic variability for salt tolerance can be generated in Diospyros species through crossings and used for overcome salt stress. Furthermore, differences in water use efficiency (WUE) have been obtained between and within populations. The information gathered at transcriptomic and physiological level demonstrated natural and heritable variability among Diospyros genus which is the key for salt-tolerant rootstock breeding programs.

MBW complexes impinge on anthocyanidin reductase gene regulation for proanthocyanidin biosynthesis in persimmon fruit.

MBW protein complexes containing MYB, bHLH and WD40 repeat factors are known transcriptional regulators of secondary metabolites production such as proanthocyanidins and anthocyanins, and developmental processes such as trichome formation in many plant species. DkMYB2 and DkMYB4 (MYB-type), DkMYC1 (bHLH-type) and DkWDR1 (WD40-type) factors have been proposed by different authors to take part of persimmon MBW complexes for proanthocyanidin accumulation in immature fruit, leading to its characteristic astringent flavour with important agronomical and ecological effects. We have confirmed the nuclear localization of these proteins and their mutual physical interaction by bimolecular fluorescence complementation analysis. In addition, transient expression of DkMYB2, DkMYB4 and DkMYC1 cooperatively increase the expression of a persimmon anthocyanidin reductase gene (ANR), involved in the biosynthesis of cis-flavan-3-ols, the structural units of proanthocyanidin compounds. Collectively, these data support the presence of MBW complexes in persimmon fruit and suggest their coordinated participation in ANR regulation for proanthocyanidin production.

A cross population between D. kaki and D. virginiana shows high variability for saline tolerance and improved salt stress tolerance.

Persimmon (Diospyros kaki Thunb.) production is facing important problems related to climate change in the Mediterranean areas. One of them is soil salinization caused by the decrease and change of the rainfall distribution. In this context, there is a need to develop cultivars adapted to the increasingly challenging soil conditions. In this study, a backcross between (D. kaki x D. virginiana) x D. kaki was conducted, to unravel the mechanism involved in salinity tolerance of persimmon. The backcross involved the two species most used as rootstock for persimmon production. Both species are clearly distinct in their level of tolerance to salinity. Variables related to growth, leaf gas exchange, leaf water relations and content of nutrients were significantly affected by saline stress in the backcross population. Water flow regulation appears as a mechanism of salt tolerance in persimmon via differences in water potential and transpiration rate, which reduces ion entrance in the plant. Genetic expression of eight putative orthologous genes involved in different mechanisms leading to salt tolerance was analyzed. Differences in expression levels among populations under saline or control treatment were found. The 'High affinity potassium transporter' (HKT1-like) reduced its expression levels in the roots in all studied populations. Results obtained allowed selection of tolerant rootstocks genotypes and describe the hypothesis about the mechanisms involved in salt tolerance in persimmon that will be useful for breeding salinity tolerant rootstocks.

Bud sprouting and floral induction and expression of FT in loquat [Eriobotrya japonica (Thunb.) Lindl.].

MAIN CONCLUSION: EjFT1 and EjFT2 genes were isolated and sequenced from leaves of loquat. EjFT1 is involved in bud sprouting and leaf development, and EjFT2 in floral bud induction. Loquat [Eriobotrya japonica (Thunb.) Lindl.] is an evergreen species belonging to the family Rosaceae, such as apple and pear, whose reproductive development, in contrast with these species, is a continuous process that is not interrupted by winter dormancy. Thus, the study of the mechanism of flowering in loquat has the potential to uncover the environmental and genetic networks that trigger flowering more accurately, contributing for a better understanding of the Rosaceae floral process. As a first step toward understanding the molecular mechanisms controlling flowering, extensive defoliation and defruiting assays, together with molecular studies of the key FLOWERING LOCUS T (FT) gene, were carried out. FT exhibited two peaks of expression in leaves, the first one in early to mid-May, the second one in mid-June. Two FT genes, EjFT1 and EjFT2, were isolated and sequenced and studied their expression. Expression of EjFT1 and EjFT2 peaks in mid-May, at bud sprouting. EjFT2 expression peaks again in mid-June, coinciding with the floral bud inductive period. Thus, when all leaves of the tree were continuously removed from early to late May vegetative apex differentiated into panicle, but when defoliation was performed from early to late June apex did not differentiate. On the other hand, fruit removal advanced EjFT1 expression in old leaves and the sooner the fruit detached, the sooner the bud sprouted. Accordingly, results strongly suggest that EjFT1 might be related to bud sprouting and leaf development, while EjFT2 might be involved in floral bud induction. An integrative model for FT functions in loquat is discussed.

Dual regulation of water retention and cell growth by a stress-associated protein (SAP) gene in Prunus.

We have identified a gene (PpSAP1) of Prunus persica coding for a stress-associated protein (SAP) containing Zn-finger domains A20 and AN1. SAPs have been described as regulators of the abiotic stress response in plant species, emerging as potential candidates for improvement of stress tolerance in plants. PpSAP1 was highly expressed in leaves and dormant buds, being down-regulated before bud dormancy release. PpSAP1 expression was moderately induced by water stresses and heat in buds. In addition, it was found that PpSAP1 strongly interacts with polyubiquitin proteins in the yeast two-hybrid system. The overexpression of PpSAP1 in transgenic plum plants led to alterations in leaf shape and an increase of water retention under drought stress. Moreover, we established that leaf morphological alterations were concomitant with a reduced cell size and down-regulation of genes involved in cell growth, such as GROWTH-REGULATING FACTOR (GRF)1-like, TONOPLAST INTRINSIC PROTEIN (TIP)-like, and TARGET OF RAPAMYCIN (TOR)-like. Especially, the inverse expression pattern of PpSAP1 and TOR-like in transgenic plum and peach buds suggests a role of PpSAP1 in cell expansion through the regulation of TOR pathway.

[Asthma incidence in Huelva, Spain at 2 stages of life: childhood and young adulthood]. / Incidencia de asma en 2 etapas de la vida: niños y adultos jóvenes de la ciudad de Huelva.

OBJECTIVE: Few studies have evaluated the incidence of asthma in Spain. Although more children than adults develop asthma every year, no study to date has analyzed the differences in incidence by following 2 age cohorts in the same geographical area. The aim of this study was to determine changes in wheezing, bronchial hyperreactivity, and asthma (in terms of onset, persistence, and remission), changes in forced expiratory volume in 1 second (FEV(1)), and asthma incidence in children (11-16 years) and young adults (20-44 years) in the city of Huelva, Spain. PATIENTS AND METHODS: We analyzed data from 2 groups studied for the first time between 1991 and 1993 and for the second time after an average follow-up period of 9 years. In the first period, data came from the Study of Respiratory Diseases in Huelva (714 children) and the European Community Respiratory Health Survey conducted in the city (271 adults). Both groups answered a respiratory symptom questionnaire, underwent spirometry testing, and completed a nonspecific bronchial challenge test with methacholine. RESULTS: In adults, onset was more common than remission for both wheezing (15.7% vs 6.9%, P=.011) and bronchial hyperreactivity (10.1% vs 3%, P=.017), and asthma incidence was 4.76 cases/1000 person-years. In children, there were more new cases than remissions for wheezing, (24.2% vs 4.3%, P=.001), bronchial hyperreactivity (13.9% vs 5.4%, P=.02), and asthma (9.3% vs 3%, P=.004). The incidence rate for asthma was 15.69 cases/1000 person-years in this age group. The annual decrease in lung function (FEV(1)) was highest in adults with wheezing (34.3 mL) and asthma (54.8 mL). CONCLUSIONS: There were more new cases of wheezing and bronchial hyperreactivity than remissions in both children and young adults. Children had a 3.3-fold higher incidence of asthma than adults in Huelva.

Incidencia de asma en 2 etapas de la vida: niños y adultos jóvenes de la ciudad de Huelva / Asthma incidence in Huelva, Spain at 2 stages of life: childhood and young adulthood

OBJETIVO: Hay pocos estudios que valoren la incidencia de asma en nuestro país. Se sabe que es mayor en niños que en adultos, pero esta diferente incidencia no se ha comprobado mediante el seguimiento de 2 poblaciones de diferente edad en el mismo ámbito geográfico. El propósito de este trabajo ha sido determinar los cambios (aparición, persistencia y remisión) de sibilancias, hiperreactividad bronquial (HB) y asma, la evolución del volumen espiratorio forzado en el primer segundo y la incidencia anual de asma en niños (11-16 años) y adultos jóvenes (20-44 años) en la ciudad de Huelva. PACIENTES Y MÉTODOS: Se ha realizado una segunda evaluación en el seguimiento de 2 grupos estudiados entre 1991 y 1993 (714 niños del Estudio de Enfermedades Respiratorias de Huelva y 271 adultos del Estudio Europeo de Enfermedades Respiratorias), con un promedio de tiempo de 9 años. Se pasó a ambos grupos un cuestionario sobre síntomas respiratorios, además de efectuar una espirometría y una prueba de provocación bronquial inespecífica con metacolina. RESULTADOS: En los adultos se encontraron más nuevas apariciones (15,7%) que remisiones (6,9%) de sibilancias (p = 0,011) e HB (apariciones: 10,1%; remisiones: 3%; p = 0,017), con una incidencia anual de asma de 4,76 casos/1.000 personas-año. Los niños mostraron más nuevas apariciones (24,2%) que remisiones (4,3%) de sibilancias (p < 0,001), HB (un 13,9% de apariciones y un 5,4% de remisiones; p = 0,02) y asma (un 9,3% de apariciones y un 3% de remisiones; p = 0,004), con una incidencia anual de asma de 15,69 casos/1.000 personas-año. La pérdida anual de función pulmonar (volumen espiratorio forzado en el primer segundo) fue más elevada en los adultos en los que aparecieron sibilancias (34,3 ml) y asma (54,8 ml). CONCLUSIONES: En ambas poblaciones, hay más nuevos casos de sibilancias e HB que remisiones. La incidencia anual de asma es 3,3 veces mayor en niños que en adultos en la ciudad de Huelva

OBJECTIVE: Few studies have evaluated the incidence of asthma in Spain. Although more children than adults develop asthma every year, no study to date has analyzed the differences in incidence by following 2 age cohorts in the same geographical area. The aim of this study was to determine changes in wheezing, bronchial hyperreactivity, and asthma (in terms of onset, persistence, and remission), changes in forced expiratory volume in 1 second (FEV1), and asthma incidence in children (11-16 years) and young adults (20-44 years) in the city of Huelva, Spain. PATIENTS AND METHODS: We analyzed data from 2 groups studied for the first time between 1991 and 1993 and for the second time after an average follow-up period of 9 years. In the first period, data came from the Study of Respiratory Diseases in Huelva (714 children) and the European Community Respiratory Health Survey conducted in the city (271 adults). Both groups answered a respiratory symptom questionnaire, underwent spirometry testing, and completed a nonspecific bronchial challenge test with methacholine. RESULTS: In adults, onset was more common than remission for both wheezing (15.7% vs 6.9%, P=.011) and bronchial hyperreactivity (10.1% vs 3%, P=.017), and asthma incidence was 4.76 cases/1000 person-years. In children, there were more new cases than remissions for wheezing, (24.2% vs 4.3%, P=.001), bronchial hyperreactivity (13.9% vs 5.4%, P=.02), and asthma (9.3% vs 3%, P=.004). The incidence rate for asthma was 15.69 cases/1000 person-years in this age group. The annual decrease in lung function (FEV1) was highest in adults with wheezing (34.3 mL) and asthma (54.8 mL). CONCLUSIONS: There were more new cases of wheezing and bronchial hyperreactivity than remissions in both children and young adults. Children had a 3.3-fold higher incidence of asthma than adults in Huelva