EjRAV1/2 Delay Flowering Through Transcriptional Repression of EjFTs and EjSOC1s in Loquat

Most species in Rosaceae usually need to undergo several years of juvenile phase before the initiation of flowering. After 4–6 years’ juvenile phase, cultivated loquat (Eriobotrya japonica), a species in Rosaceae, enters the reproductive phase, blooms in the autumn and sets fruits during the winter. However, the mechanisms of the transition from a seedling to an adult tree remain obscure in loquat. The regulation networks controlling seasonal flowering are also largely unknown. Here, we report two RELATED TO ABI3 AND VP1 (RAV) homologs controlling juvenility and seasonal flowering in loquat. The expressions of EjRAV1/2 were relatively high during the juvenile or vegetative phase and low at the adult or reproductive phase. Overexpression of the two EjRAVs in Arabidopsis prolonged (about threefold) the juvenile period by repressing the expressions of flowering activator genes. Additionally, the transformed plants produced more lateral branches than the wild type plants. Molecular assays revealed that the nucleus localized EjRAVs could bind to the CAACA motif of the promoters of flower signal integrators, EjFT1/2, to repress their expression levels. These findings suggest that EjRAVs play critical roles in maintaining juvenility and repressing flower initiation in the early life cycle of loquat as well as in regulating seasonal flowering. Results from this study not only shed light on the control and maintenance of the juvenile phase, but also provided potential targets for manipulation of flowering time and accelerated breeding in loquat.

Constitutive deficiency of the neurogenic hippocampal modulator AP2γ promotes anxiety-like behavior and cumulative memory deficits in mice from juvenile to adult periods

The transcription factor activating protein two gamma (AP2γ) is an important regulator of neurogenesis both during embryonic development as well as in the postnatal brain, but its role for neurophysiology and behavior at distinct postnatal periods is still unclear. In this work, we explored the neurogenic, behavioral, and functional impact of a constitutive and heterozygous AP2γ deletion in mice from early postnatal development until adulthood. AP2γ deficiency promotes downregulation of hippocampal glutamatergic neurogenesis, altering the ontogeny of emotional and memory behaviors associated with hippocampus formation. The impairments induced by AP2γ constitutive deletion since early development leads to an anxious-like phenotype and memory impairments as early as the juvenile phase. These behavioral impairments either persist from the juvenile phase to adulthood or emerge in adult mice with deficits in behavioral flexibility and object location recognition. Collectively, we observed a progressive and cumulative impact of constitutive AP2γ deficiency on the hippocampal glutamatergic neurogenic process, as well as alterations on limbic-cortical connectivity, together with functional behavioral impairments. The results herein presented demonstrate the modulatory role exerted by the AP2γ transcription factor and the relevance of hippocampal neurogenesis in the development of emotional states and memory processes.

Comprehensive Analysis of Five Phyllostachys edulis SQUA-like Genes and Their Potential Functions in Flower Development

Bamboo is one of the most important non-timber forest resources worldwide. It has considerable economic value and unique flowering characteristics. The long juvenile phase in bamboo and unpredictable flowering time limit breeding and genetic improvement and seriously affect the productivity and application of bamboo forests. Members of SQUA-like subfamily genes play an essential role in controlling flowering time and floral organ identity. A comprehensive study was conducted to explain the functions of five SQUA-like subfamily genes in Phyllostachys edulis. Expression analysis revealed that all PeSQUAs have higher transcript levels in the reproductive period than in the juvenile phase. However, PeSQUAs showed divergent expression patterns during inflorescence development. The protein–protein interaction (PPI) patterns among PeSQUAs and other MADS-box members were analyzed by yeast two-hybrid (Y2H) experiments. Consistent with amino acid sequence similarity and phylogenetic analysis, the PPI patterns clustered into two groups. PeMADS2, 13, and 41 interacted with multiple PeMADS proteins, whereas PeMADS3 and 28 hardly interacted with other proteins. Based on our results, PeSQUA might possess different functions by forming protein complexes with other MADS-box proteins at different flowering stages. Furthermore, we chose PeMADS2 for functional analysis. Ectopic expression of PeMADS2 in Arabidopsis and rice caused early flowering, and abnormal phenotype was observed in transgenic Arabidopsis lines. RNA-seq analysis indicated that PeMADS2 integrated multiple pathways regulating floral transition to trigger early flowering time in rice. This function might be due to the interaction between PeMADS2 and homologous in rice. Therefore, we concluded that the five SQUA-like genes showed functional conservation and divergence based on sequence differences and were involved in floral transitions by forming protein complexes in P. edulis. The MADS-box protein complex model obtained in the current study will provide crucial insights into the molecular mechanisms of bamboo’s unique flowering characteristics.

Variation in size distribution of juvenile pink shrimps Farfantepenaeus brasiliensis and F. paulensis in the estuarine-adjacent ocean area of Cananéia, south-eastern coast of Brazil

The study characterized the structure of juveniles and sub-adults of Farfantepenaeus brasiliensis and F. paulensis in the Cananéia-Iguape estuarine lagoon system and its adjacent coastal area by evaluating the period of juvenile recruitment, sex ratio, growth, longevity, natural mortality, and development time until the late juvenile phase. Samples were collected from July 2012 to June 2014. Shrimps were identified by species and sex, and measured (carapace length – CL mm); 889 individuals of F. brasiliensis and 848 of F. paulensis were analysed. Females were more abundant than males for both species. The growth parameters of F. brasiliensis were: CL∞ = 45.5 mm, k = 1.8 year−1 for males and CL∞ = 55.2 mm, k = 1.6 year−1 for females; longevity of 2.52 years (males) and 2.88 years (females); and natural mortality of 1.71 (males) and 1.55 (females). For F. paulensis, the following values were observed: CL∞ = 40.7 mm, k = 2.3 year−1 for males and CL∞ = 56.5 mm, k = 1.9 year−1 for females; longevity of 2.04 years (males) and 2.37 years (females); and natural mortality of 2.39 (males) and 2.05 (females). The juvenile recruitment of both species peaked in January 2014. The development time until late juvenile phase was ~7 months (F. brasiliensis) and ~5 months (F. paulensis). Even though the highest abundance of juveniles did not occur in the closed season, fishing is forbidden in the estuarine area and the migration towards the adult population occurred close to or even during the closed season.

Changes in Haemolymph Biochemical values during different growth phases in African Giant Land Snail (Archachatina Marginata) Swainson

The impact of growth phases on the haemolympy biochemical value of African giant land snail Archachatina marginata was studied. The growth phases were: snailet, juvenile and Adult based on the number of whorls on the shell and weight of the snails. Highest concentration of glucose and lipids were recorded at the juvenile phase (40.20mg/dl), while least values for glucose (20.00mg/dl) and lipids (37.80mg/dl)were recorded during snailer and adult phases respectively. A progressive increase in the concentration of protein was observed as the snails moved from snailetphase to adult phase, hence snails in adult phase had highest concentration of protein in their haemolymph. Growth phases significantly (p<0.05) affected the haemolymph mineral composition of the snails, juvenile phase had the highest values in ca2+,PO4+ and Na+, while the adult phase recorded the least concentration in ca2+, Na amd cl-2. Juvenile growth phase of A. marginata thus has better haemolymph biochemical values than both snailet and adult growth phases.

Detection of Pseudomonas sp. in pirarucu (Arapaima gigas): a case report in the Western Amazon

Pirarucu (Arapaima gigas)is one of the most important fish in Amazonian fish farming. However, information about its nutritional, zootechnical and microbiological aspects is still scarce. This is especially true for the juvenile phase due to high mortality rates caused by malnutrition, difficulties in food training, endo and ectoparasite infestations, which in turn lead to immunosuppression, favoring secondary bacterial infections that may be present due to various environmental factors(e.g., sudden temperature variations, water acidity and pollution of the aquatic environment) and thestatus of fish. The Pseudomonas sp. species studied in this work is part of the aquatic ecosystem and is considered a contaminant or invader because it infects a wide variety of aquatic species, including pirarucu. Given this assumption, the objective of the study was to report a case of Pseudomonas sp.in the viscera and dorsum of a juvenile pirarucuArapaima gigas(SCHINZ, 1822) detected through bacteriological analysis. In the fish production chainin the Western Amazon, pirarucu is one of the most prominent fish species because of its high zootechnical performance in terms of weight gain and commercial value. However, one of the biggest obstacles in its production chain occurs during the juvenile phase, with high mortality rates caused by mainly bacterial infections, leading to economic losses in fish farming. In this study, Pseudomonas sp. was detected in a sample of dorsum and viscera of a pirarucu fish from a fish farm in the municipality of OuroPreto do Oeste, Rondônia, Brazil.

BEHAVIOR OF SOME WALNUT VARIETIES UNDER JUVENILE PHASE TO BACTERIOSE AND ANTRACNOSE ATTACK

Walnut (Juglans regia L.) is an important species for the European and Romanian fruit growing, but, despite its resilience, it can be attacked by specific diseases such as bacteriose (Xanthomonas arboricola pv. juglandis (Pierce) Dye) and anthracnose (Gnomonia leptostyla D.C. Trav) which due to the climatic changes became more active than in the past decades. This paper presents results on the behavior of 48 walnut varieties preserved into the new collection established at RIFG Pitesti Romania to the field infections with these pathogens, their resilience in juvenile phase and their overall classification. The data collected reveal that the microclimate conditions during years of the study (2018-2020) were very favorable for the walnut diseases attack. The correlations monthly average temperatures (*C) -- average leaf wetness hours sum (h/month) and monthly average precipitation sum (mm) -- average leaf wetness hours sum (h/month), contributed to the infections speed and diseases development on the studied biologic material. For these the coefficients R2=0.6086*** (r=0.7801***, n=35) and R2=0.5584*** (r=0.7472***, n=35) were calculated. Under such circumstances, the best behavior on the walnut blight had the varieties: 'Făleşti', 'Geoagiu 453', 'Jupâneşti', 'Miroslava', 'Novaci', 'Timval', 'Valcor', 'Valrex', 'Velniţa', 'Victoria' and 'Vlădeşti' with damages degree DD% on leaves no higher than 0,03. Also, The most resilient on anthracnose attack on leaves were the varieties: 'Argeşean', 'Gemenea 20', 'Pestişani', 'Pecianski', 'Schinoasa', (DD%=0.13), 'Valcris' (DD%=0.11), 'Codrene', 'Secular RM', 'Sibişel 265' (DD%=0.10) and 'Valrex' (DD%=0.05).

γ-Aminobutyric Acid Participates in the Adult-Phase Adventitious Rooting Recalcitrance

In many tree species especially the rooting-recalcitrant woody perennials, the adventitious root (AR) in the juvenile phase can be easily induced by exogenous auxin, but AR formation becomes recalcitrant in the adult phase. Also, it is reported that the γ-aminobutyric acid (GABA) inhibits primary root growth in Arabidopsis and the AR formation in poplar (Populus ssp). So far, how GABA affects or is affected by the ontogenetic phase or auxin remains unclear. Here, we used an apple rootstock, Malus xiaojinensis, and tobacco (Nicotiana benthamiana) to investigate this question. We first analyzed the content of GABA, the activity of GABA synthetic enzyme GAD, and the expression of the coding gene MxGADs, respectively, in leafy cuttings of juvenile and adult phase. Next, the effect of exogenous GABA on AR formation was examined in in vitro shoots of M. xiaojinensis and tobacco. Interestingly, significant and consistent increases in GABA concentration, GAD activity, and expression of MxGAD genes in response to exogenous indole butyric acid (IBA) were detected in adult-phase cuttings, but not in juvenile-phase cuttings. Exogenous GABA application inhibited the AR formation by delaying rooting time and reducing root number and the total root length in in vitro shoots of both M. xiaojinensis and tobacco. The expression of MxPIN members increased in response to IBA application, but these changes were restrained by the addition of GABA. These results indicate that both the loss of juvenility and IBA are required to trigger GABA accumulation. GABA may affect the AR formation as a co-actor by inhibiting polar auxin transport. Together, these findings facilitate the understanding of the regulatory network among GABA, juvenility, and auxin signaling on the AR formation.

Factors Affecting Bulblet Growth of Lilium sp. - Tracking Ontogenic Development and Bulb Production in vitro

Poor growth of bulblet and ontogenic development are the major problems of adventitious bulb production of lilies in vitro through explant culture. Ontogenic development from the juvenile phase to the adult vegetative phase strongly correlates with bulblet growth of lily, and it is important to understand how lily bulblets grow in vitro. This study was at aimed to determining an effective in vitro culture process for lily to track bulblet growth, ontogenic development, and bulb production. In the results, bulblet performance was higher with the increase in the amount of medium; however, bulblet size was not satisfactory and was in the juvenile phase under an inducing condition. The threshold weight at which 100% ontogenic development was about 300 mg. Avoiding depletion of sucrose in the media is the key to achieving desired bulblet growth and ontogenic development in vitro and indicates growth could be sustained by subculture. The circumference of bulblets increases with its weight after subcultured in vitro. Therefore, a threshold circumference of about 3.2 cm in proportion to bulblet fresh weight of 300 - 350 mg may be an indicator of ontogenic development. Plant Tissue Cult. & Biotech. 30(1): 1-13, 2020 (June)