Rhizogenic induction in adult Juglans regia l. cv. serr tissue induced by indole butyric acid and Agrobacterium rhizogenes .

The in vitro introduction of adult walnut ( Juglans regia L.) tissue represents an opportunity to clone elite genotypes whose selection occurs in advanced ontogenic states. With the purpose of developing a protocol to allow mass propagation of valuable genotypes from adult material, a comparison was made between two root induction systems of walnut microshoots of the fourth subculture of adult walnut tissue of an in vitro introduction program previously reinvigorated through traditional grafting. Rhizogenic induction by indole-3-butyric acid (IBA) and Agrobacterium rhizogenes was used. The rhizogenic process was analyzed in two phases for both auxinic (T1: 3 mg L -1 IBA; T2: 5 mg L -1 IBA) and A. rhizogenes inductions (T3: A-477; T4: A-478). The first phase of root induction was during 3 days in the dark while the second phase, root manifestation, was 27 days. Rooting percentage was evaluated and the induced root systems characterized (number, length, diameter, and root insertion zone) in all the procedures. The best rooting results were obtained in T2, although the response obtained with A. rhizogenes didn′t differ from the T1 response. This appears to be an increasingly interesting methodology for adventitious rhizogenesis in this species

Modelling the Effect of Weed Competition on Long-Term Volume Yield of Eucalyptus globulus Labill. Plantations across an Environmental Gradient

Several studies have quantified the responses of Eucalyptus globulus Labill. plantations to weed control on its early development (2–3 years after establishment). However, long-term results of competing vegetation effects have not been included into growth and yield models that incorporate treatments of competing vegetation control, and its interaction with site resource availability. In this article, we compared several models predicting stand volume yield of E. globulus plantations established across an environmental gradient, growing under different intensity levels of competing vegetation control. Four sites were selected encompassing a gradient in rainfall and amount of competing vegetation. Treatments were applied at stand establishment and were monitored periodically until age 9 years. Competing vegetation control intensity levels considered 0, 5, 20, 44, and 100% weed-free cover around individual E. globulus cuttings. Maximum competing vegetation biomass production during the first growing season were 2.9, 6.5, 2.2, and 12.9 Mg ha−1, for sites ranging from low to high annual rainfall. As expected, reductions in volume yield at age 9 years were observed as competing vegetation control intensity decreased during the first growing season. A strong relationship was established between stem volume yield loss and the intensity of competing vegetation control, the amount of competing vegetation biomass produced during the first growing season and mean annual rainfall. The slope of the relationship was different among sites and was related mainly to water and light limitations. Our results suggest that the biomass of competing vegetation (intensity of competition), affecting site resource availability, contribute to observed long-term effects on E. globulus plantations productivity. The site with the lowest mean annual rainfall showed the highest volume yield loss at age 9 years. Sites with highest rainfall showed contrasting results related to the amount of competing vegetation biomass

Light energy management in micropropagated plants of Castanea sativa, effects of photoinhibition

The limited development of photoprotective mechanisms, specifically heat dissipation capacity, found in micropropagated plants may be the result of low xanthophyll cycle pigment content and reduced de-epoxidation capacity making them highly susceptible to photodamage. The effects of gradual or sudden increase of light on Castanea sativa in vitro cultured and during their ex vitro transference was evaluated. The results were compared with those determined in nursery-grown plants. In vitro plants responded poorly to gradual increase in irradiance, exhibiting a low electron transport rate (ETR) agreeing with low non-photochemical quenching (NPQ) and a limited de-epoxidation capacity, not synthesizing detectable amounts of zeaxanthin (Z). Regarding a sudden increase in light (photoinhibition treatment, PhT); post-PhT as in vitro as well nursery plants showed a significant decrease in their maximal efficiency of PSII (F-v/F-m), but in vitro the decrease was very drastic (around 0.2) different from that observed in nursery (around 0.69). In vitro, NPQ was mainly determined by the slow relaxing component, NPQ(s) (80.8%), concomitant with a pronounced decrease of DI protein post-PhT, and a lack of de-epoxidation capacity. During ex vitro transfer, PhT lead to death of some plants, specifically during root induction. The photoprotective mechanisms were activated over time in ex vitro conditions, indicating that micropropagated Castanea sativa display a potential for light acclimation, adjusting their photosynthetic apparatus to the ambient growth irradiance. Understanding the mechanisms that micropropagated plants deployed and how they face high light intensity events, will allow us to search for strategies to improve performance to possible light fluctuations that normally occur in ex vitro conditions during plant acclimation. (C) 2012 Elsevier Ireland Ltd. All rights reserved

Influence of in vitro growth conditions on the photosynthesis and survival of Castanea sativa plantlets during ex vitro transfer

Adequate in vitro micro-environments are crucial to induce life compatible leaf development. Key morphological and physiological traits are needed to allow ex vitro survival. We study, how in vitro light and ventilation affect physiological performance and survival of ex vitro Castanea sativa plantlets. In vitro treatments consisted of two irradiances of 50 and 150 A mu mol m(-2) s(-1) in ventilated vessels (VL50 and VL150, respectively), compared to traditional cultures at 50 A mu mol m(-2) s(-1) in non-ventilated vessels (NVL50). After the exposure to each condition a photoinhibitory treatment (PhT) was also applied to study whether the above in vitro conditions exerted photoprotection and facilitated the recovery of C. sativa during sudden ex vitro transfer. During rooting, a decrease in net photosynthesis (Psat), electron transport rate (ETRII) and maximal efficiency of PSII (F (v) /F (m) ) were observed. Transpiration rates (E) decreased, concomitantly with a rise in water use efficiency (WUE), mainly in microplants originating from ventilated treatments (V). Throughout this stage, the PhT was lethal for all in vitro treatments. During acclimation, the number and leaf size increased principally in plantlets originating from V treatments. These microplants were also able to recover their ETR and F (v) /F (m) . Initially, the PhT produced a drastic drop in F-v/F-m of plantlets in all treatments however they did show a tendency to recover. Transferring plantlets to the greenhouse produced a decrease in the Psat in all treatments; however, over time Psat increased reaching values of 3.2 and 5.3 mu mol CO2 m(-2) s(-1) in microplants originating from VL50 and VL150, respectively. Transpiration rate were similar in all treatments and remained at levels of about 0.9 mmol H2O m(-2) s(-1); thus, WUE increased significantly, reaching values of almost 3.8 A mu mol CO2/mmol H2O in microplants originating from VL150. After the PhT, all of the plantlet's recovery capacity increased concomitantly with their dynamic heat dissipation and their de-epoxidation capacity. Our results suggest that managing in vitro conditions can improve plantlets photosynthetic performance in early stages after ex vitro transfer, playing a key role in the ameliorating the transfer stress

Seasonal changes in photosynthesis, phenolic content, antioxidant activity, and anatomy of apical and basal leaves of Aristotelia chilensis

Aristotelia chilensis (Mol.) Stuntz is an evergreen species endemic to Chile. It grows in open areas or under tree canopy, and its leaves emerge in early spring and summer. The objective of this study was to determine changes in photosynthetic parameters, total phenol content (TPC), antioxidant activity, and anatomy of apical and basal leaves of A. chilensis during the year. Photosynthesis performance was determined by measuring electron transport rate (ETR), the quantum efficiency of photosystem II (Fv/Fm), photochemical quenching (qP), and non-photochemical quenching (NPQ) with a fluorimeter. Leaf extracts were analysed to determine TPC and antioxidant activity. The maximum ETR and qP were recorded in spring and summer when the photosynthetically active radiation (PAR) at midday was higher (1901 and 1968 µmol m-2 s-1, respectively) than in other parts of a year. The Fv/Fm had typical physiological values in both types of leaves (about 0.8 in all the seasons). Also the NPQ was not influenced by the kind of leaves and season of the year. In concordance, the basal spring leaves had the highest TPC values. In contrast, the highest values of antioxidant activity were recorded in basal winter leaves followed by basal spring leaves. The results suggested that an increase in PAR (spring) positively affected the antioxidant activity and TPC, which correlated with higher ETR and qP values. The apical leaves showed morphological adaptations during the year and areas of intercellular spaces and palisade parenchyma were larger than in the basal leaves.This research was supported by the VRID project 218.142.037-1.0 "Evaluation of phenolic and alkaloids compounds production from vegetative organs of Aristotelia chilensis: an effective alternative for sustainable use”; Universidad de Concepción, Chile. The authors are grateful for the support provided by Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brasil. Beca ANID Doctorado Nacional 2019/21191038 is greatly acknowledge

Comparative Study of Metabolomic Profile and Antioxidant Content of Adult and In Vitro Leaves of <i>Aristotelia chilensis</i>

This work aimed to identify the bioactive compounds present in adult maqui (Aristotelia chilensis) leaves from different stages of development and seasons of the year and compare them with leaves obtained from maqui plants grown in vitro. The qualitative and quantitative analysis of maqui leaf extracts by HPLC-DAD-ESI-MSn showed the presence of different polyphenolic compounds classified into galloyl and caffeoyl quinic acids, ellagitannins and ellagic acid- and flavonoid-derivatives. In general, the total phenolic content of the in vitro samples was higher than that of ex vitro samples, whereas the total flavonoid content was higher in winter basal leaves. Additionally, the analysis by HPLC-MS showed that the extract from spring basal leaves was enriched in quercetin, catechin, kaempferol and 3-caffeoyl quinic acids, while in the in vitro leaves extract, quercetin was not present. As regards lipophilic compounds identified by GC/MS, the samples of in vitro leaves showed a high presence of α-tocopherol and β-sitosterol. In contrast, the samples of adult leaves presented a hight level of linolenic and linoleic acids. These results suggest that maqui leaves could be an excellent source of antioxidants and lipophilic compounds for many industries, such as the nutraceutical and pharmaceutical industries