Self-incompatibility in apricot: identifying pollination requirements to optimize fruit production

In recent years, an important renewal of apricot cultivars is taking place worldwide, with the introduction of many new releases. Self-incompatible genotypes tolerant to the sharka disease caused by the plum pox virus (PPV), which can severely reduce fruit production and quality, are being used as parents in most breeding programs. As a result, the self-incompatibility trait present in most of those accessions can be transmitted to the offspring, leading to the release of new self-incompatible cultivars. This situation can considerably affect apricot management, since pollination requirements were traditionally not considered in this crop and information is lacking for many cultivars. Thus, the objective of this work was to determine the pollination requirements of a group of new apricot cultivars by molecular identification of the S-alleles through PCR amplification of RNase and SFB regions with different primer combinations. The S-genotype of 66 apricot cultivars is reported, 41 for the first time. Forty-nine cultivars were considered self-compatible and 12 self-incompatible, which were allocated in their corresponding incompatibility groups. Additionally, the available information was reviewed and added to the new results obtained, resulting in a compilation of the pollination requirements of 235 apricot cultivars. This information will allow an efficient selection of parents in apricot breeding programs, the proper design of new orchards, and the identification and solution of production problems associated with a lack of fruit set in established orchards. The diversity at the S-locus observed in the cultivars developed in breeding programs indicates a possible genetic bottleneck due to the use of a reduced number of parents

Warm temperatures at bloom reduce fruit set in sweet cherry

Warm springs have often been assumed as a prelude of a good fruit set in temperate fruit tree species. However, recently, evidences have accumulated on erratic fruit set under apparently good and warm springs in Mediterranean conditions. The fact that these observations mainly occurred in sweet cherry (Prunus avium), a species adapted to high latitudes and cold climates raised the question of whether warm temperatures at flowering could have a detrimental effect on fruit set. To evaluate this hypothesis two different sweet cherry cultivars were subjected under field conditions to a slight increase in temperature at bloom over two different years. While the minimum temperature remained stable, the maximum temperature increased 5-7ºC, resulting in a moderate increase of the average temperature of 1-3ºC. This was sufficient to drastically reduce fruit set in both years and cultivars. To know the vulnerable phase to warm temperatures the process was timed back: final fruit set differences were established in the first three weeks following pollination, but the onset of fruiting – when these differences appeared – was tracked back to one week after pollination. The process from pollination to fertilization was examined under both conditions. Fertilization occurred six days after pollination. Higher temperatures accelerated pollen tube growth rate but also reduced the number of growing pollen tubes along the style. In the ovary, the warm treatment accelerated ovule degeneration. These findings alert on the potential negative effect of even slight increases in temperature during cherry blooming, which nowadays – due to global warming trends – is a plausible and realistic scenario under Mediterranean climatic conditions

Editorial: Breeding Innovations in Underutilized Temperate Fruit Trees

The recent growing interest in minor species (i.e., fig, pomegranate, feijoa, etc.) has recently driven new research on breeding and genetics to address producer and consumer traits. Since these species have received little attention from the scientific community, they were less improved via conventional breeding, and lacked detailed genomic information on important traits. This lack of data, together with a general poor genetic knowledge of these species, has limited a wider cultivation of varieties with improved characteristics

Albaricoquero: renovación varietal y necesidades de polinización

La reconversión varietal que se está produciendo en el albaricoquero es la respuesta ante diversos problemas que ha presentado el cultivo en los últimos años. El rápido lanzamiento de nuevas variedades desarrolladas en programas de mejora de todo el mundo ha provocado que las necesidades de polinización sean un factor importante a tener cada vez más en cuenta en el cultivo

Male Meiosis as a Biomarker for Endo- to Ecodormancy Transition in Apricot

Dormancy is an adaptive strategy in plants to survive under unfavorable climatic conditions during winter. In temperate regions, most fruit trees need exposure to a certain period of low temperatures to overcome endodormancy. After endodormancy release, exposure to warm temperatures is needed to flower (ecodormancy). Chilling and heat requirements are genetically determined and, therefore, are specific for each species and cultivar. The lack of sufficient winter chilling can cause failures in flowering and fruiting, thereby compromising yield. Thus, the knowledge of the chilling and heat requirements is essential to optimize cultivar selection for different edaphoclimatic conditions. However, the lack of phenological or biological markers linked to the dormant and forcing periods makes it difficult to establish the end of endodormancy. This has led to indirect estimates that are usually not valid in different agroclimatic conditions. The increasing number of milder winters caused by climatic change and the continuous release of new cultivars emphasize the necessity of a proper biological marker linked to the endo- to ecodormancy transition for an accurate estimation of the agroclimatic requirements (AR) of each cultivar. In this work, male meiosis is evaluated as a biomarker to determine endodormancy release and to estimate both chilling and heat requirements in apricot. For this purpose, pollen development was characterized histochemically in 20 cultivars over 8 years, and the developmental stages were related to dormancy. Results were compared to three approaches that indirectly estimate the breaking of dormancy: an experimental methodology by evaluating bud growth in shoots collected periodically throughout the winter months and transferred to forcing chambers over 3 years, and two statistical approaches that relate seasonal temperatures and blooming dates in a series of 11–20 years by correlation and partial least square regression. The results disclose that male meiosis is a possible biomarker to determine the end of endodormancy and estimate AR in apricot. Copyright © 2022 Herrera, Lora, Fadón, Hedhly, Alonso, Hormaza and Rodrigo

901-5 Intravenous Amiodarone Restores Sinus Rhythm in Acute Myocardial Infarction Complicated with Atrial Fibrillation

The effectiveness and tolerance of intravenous (IV) amiodarone (Am) in atrialfibrillation (AF) complicated acute myocardial infarction (AMI) is not well studied. Thus, twenty patients (Pts) with AMI complicated with AF occurring within 30h (11.9 ± 10) of the onset of AMI symptoms were treated with IV administration of digitalis (d, 0.5mg and an additional 0.25mg later) followed by IV Am 300mg over 2h (starting 2h after the initial dose of d) and followed by 44mg/h for up to 3 days, if sinus rhythm (SR) was not restored. Intravenous d restored SR within 2h in 5/20pts. AF relapsed in 2 of them. Subsequent administration of Am for 2 h restored SR in the remaining 15/20pts and in the 2pts in whom AF had relapsed after the initial restoration of SR by d. Am restored SR within an average of 12.8 (range 0.5–56) h of infusion. Total dose of Am was 1922 ± 720mg in 4pts and 425 ± 241mg in the remaining 13. Am was well tolerated by all pts including 1 with cardiogenic shock assisted with the intraaortic balloon pump. In conclusion, IV Am administration ishighly effective in restoring sinusrhythm in AF complicating AMI and is well tolerated

The progamic phase of an early-divergent angiosperm, Annona cherimola (Annonaceae)

33 Pag. The definitive version, with the figures, is available at: http://aob.oxfordjournals.org/Background and Aims: Recent studies of reproductive biology in ancient angiosperm lineages are beginning to shed light on the early evolution of flowering plants, but comparative studies are restricted by fragmented and meagre species representation in these angiosperm clades. In the present study, the progamic phase, from pollination to fertilization, is characterized in Annona cherimola, which is a member of the Annonaceae, the largest extant family among early-divergent angiosperms. Beside interest due to its phylogenetic position, this species is also an ancient crop with a clear niche for expansion in subtropical climates. Methods: The kinetics of the reproductive process was established following controlled pollinations and sequential fixation. Gynoecium anatomy, pollen tube pathway, embryo sac and early post-fertilization events were characterized histochemically. Key Results: A plesiomorphic gynoecium with a semi-open carpel shows a continuous secretory papillar surface along the carpel margins, which run from the stigma down to the obturator in the ovary. The pollen grains germinate in the stigma and compete in the stigma-style interface to reach the narrow secretory area that lines the margins of the semi-open stylar canal and is able to host just one to three pollen tubes. The embryo sac has eight nuclei and is well provisioned with large starch grains that are used during early cellular endosperm development. Conclusions: A plesiomorphic simple gynoecium hosts a simple pollen–pistil interaction, based on a support–control system of pollen tube growth. Support is provided through basipetal secretory activity in the cells that line the pollen tube pathway. Spatial constraints, favouring pollen tube competition, are mediated by a dramatic reduction in the secretory surface available for pollen tube growth at the stigma–style interface. This extramural pollen tube competition contrasts with the intrastylar competition predominant in more recently derived lineages of angiosperms.This work was supported by the Spanish Ministry of Education (Project Grants AGL2004-02290/AGR, AGL2006-13529 and AGL2007-60130/AGR), GIC-Aragón 43, Junta de Andalucía (AGR2742), and the European Union under the INCO-DEV program (Contract 015100). J.L. was supported by a grant from Junta de Andalucía.Peer reviewe

Challenge 5: Impact of global change on managed ecosystems

Topic Coordinators: María Begoña García ( IPE, CSIC ); Pedro Jordano ( EBD, CSIC )Peer reviewe

Mapping Genetic Diversity of Cherimoya (Annona cherimola Mill.): Application of Spatial Analysis for Conservation and Use of Plant Genetic Resources

There is a growing call for inventories that evaluate geographic patterns in diversity of plant genetic resources maintained on farm and in species' natural populations in order to enhance their use and conservation. Such evaluations are relevant for useful tropical and subtropical tree species, as many of these species are still undomesticated, or in incipient stages of domestication and local populations can offer yet-unknown traits of high value to further domestication. For many outcrossing species, such as most trees, inbreeding depression can be an issue, and genetic diversity is important to sustain local production. Diversity is also crucial for species to adapt to environmental changes. This paper explores the possibilities of incorporating molecular marker data into Geographic Information Systems (GIS) to allow visualization and better understanding of spatial patterns of genetic diversity as a key input to optimize conservation and use of plant genetic resources, based on a case study of cherimoya (Annona cherimola Mill.), a Neotropical fruit tree species. We present spatial analyses to (1) improve the understanding of spatial distribution of genetic diversity of cherimoya natural stands and cultivated trees in Ecuador, Bolivia and Peru based on microsatellite molecular markers (SSRs); and (2) formulate optimal conservation strategies by revealing priority areas for in situ conservation, and identifying existing diversity gaps in ex situ collections. We found high levels of allelic richness, locally common alleles and expected heterozygosity in cherimoya's putative centre of origin, southern Ecuador and northern Peru, whereas levels of diversity in southern Peru and especially in Bolivia were significantly lower. The application of GIS on a large microsatellite dataset allows a more detailed prioritization of areas for in situ conservation and targeted collection across the Andean distribution range of cherimoya than previous studies could do, i.e. at province and department level in Ecuador and Peru, respectively