Fruits of the cherimoya tree (Annona cherimola Mill.) were consumed by native cultures in Central America, from where the crop was disseminated to South America in pre-Columbian times. Despite its historical significance and cultivation in subtropical regions worldwide, cherimoya remains an underutilized crop, particularly in its area of origin where the conservation of its genetic diversity is under threat. In this study, we provide a comprehensive overview of the research performed on this fruit tree over the past two decades, shedding light on its current status in terms of commercial production and germplasm conservation efforts in the main cherimoya producing countries in the Americas and Europe.

Citronella mucronata (C. mucronata), a tree species endemic to Chile, has become threatened in its natural habitat and is currently listed as vulnerable. Tree population parameters have deteriorated due to indiscriminate logging and other anthropogenic activities, warranting research on mass propagation as a means of recovery. This study, unprecedented for this native species, has developed a successful method for its micropropagation. The objective was to establish a protocol for in vitro propagation of C. mucronata to produce large quantities of high-quality seedlings in an accelerated plant acquisition process. The best results were achieved by growing explants on Murashige and Skoog (MS) basal culture medium supplemented with 4.44 μM 6-benzylaminopurine (BAP) and 14.76 μM indole-3-butyric acid (IBA). Explant survival rate was 78 %, the average shoot length reached 3.2 cm, the number of lateral shoots was 3.9, and rooting rate was 60%. Furthermore, stimulation with red and blue light in a 1:2 ratio, supplemented with 14.76 μM IBA, improved the rooting rate to 93%. The survival rate of rooted explants reached 100% in the acclimatization stage when using peat and perlite substrate (1:1 v/v).

Citrus orchards in semi-arid regions are increasingly exposed to drought conditions due to climate change. This study compared the physiological and growth responses of ‘W. Murcott’ tangor (WM) grafted onto Citrus macrophylla (M), Swingle citrumelo (SC), C-35 citrange (C35), or bitter citrandarin (C22) rootstock subjected to two irrigation treatments: daily irrigation to replace 100% of the water lost daily by evapotranspiration (ET; control treatment) or daily irrigation to replace 75% of the water lost daily by ET (water deficit treatment). For trees in each treatment, leaf gas exchange, relative chlorophyll content, chlorophyll fluorescence, midday stem water potential, trunk cross-sectional area, and shoot length were measured 46 days after treatments were initiated. The results showed that WM on SC or C22 rootstock exhibited isohydric behavior, where decreased stomatal conductance limited transpiration in the water deficit treatment. WM on M rootstock exhibited an anisohydric response in the water deficit treatment, where there was no stomatal control of water loss by transpiration. Among the rootstocks tested for WM, the most tolerant to soil water deficit was SC, whereas trees on M rootstock were the most negatively affected by soil water deficit.

Alstroemeria pelegrina (A. pelegrina), a Chilean endemic, is considered vulnerable as its natural habitat is currently threatened. The decline in the reproductive capacity of the species due to anthropogenic impacts and climate change has made it imperative to address the problem by developing large-scale propagation methods. The objective of this study was to establish protocols for breaking the dormancy and in vitro germination of A. pelegrina seeds to speed up the germination and seedling production processes. The research began with morphological observations of the reproductive process, followed by in vitro sowing. The results showed that the seeds reached full maturity in 51 days, and physiological maturity in 41 days, at which point the seeds could be harvested for in vitro germination. The mechanical scarification pretreatment improves the in vitro germination rate to 96% and the germination time to 7 days, showing that the species is characterized by physical seed dormancy. On the other hand, if the seed coat incisions are deeper than 0.5 mm, 30% of the potential plants are lost due to embryo damage. The study provides scientific evidence for the feasibility of large-scale in vitro propagation of the species and establishes an efficient method of seedling production.

Peumus boldus Mol (P. boldus), a Chilean endemic tree species occurring in sclerophyllous or evergreen forests, has historically played a significant role in indigenous ancestral medicine. Recently, P. boldus has garnered renewed attention, spurred by the growing interest in its leaves and bark. These parts contain a wealth of bioactive agents, including alkaloids, flavonoids, essential oils, and potent antioxidant properties attributed to their high phenolic compound content. However, the species’ regeneration within its native habitat has been hindered by a confluence of factors such as climate change, agricultural activities, and shifts in land use. Coupled with the seeds’ low germination rate and protracted emergence period, the necessity to develop large-scale propagation methods to bolster P. boldus population numbers has become increasingly evident. Furthermore, the widespread use of P. boldus for medicinal purposes renders it vulnerable to overexploitation, thereby underscoring the need for a comprehensive mass propagation protocol to support conservation efforts. Thus, the main objective of this study was to formulate an in vitro protocol for mass regeneration of P. boldus. The explants excised from nodal sections demonstrated an average survival rate of 74%, while the application of 6-benzylaminopurine (4.44 μM) yielded an average shoot length of 5.9 cm. In vitro shoot rooting achieved a success rate of 80% using perlite supplemented with indole-3-butyric acid (9.84 μM). During the acclimation phase, in vitro rooted plants displayed a remarkable 100% survival rate at the 30-day mark after being transplanted into a substrate consisting of perlite and peat in a (1:1 v/v) ratio.

The Chilean rhizomatous geophyte Alstroemeria pelegrina (A. pelegrina), a species endemic to the Coquimbo (31°45′ S) and Valparaíso (33°12′ S) regions, is currently classified as vulnerable and experiencing population decline due to loss of habitat. This heightened threat underscores the need to develop effective mass propagation techniques to support its conservation efforts. Consequently, the present study aimed to establish an optimized in vitro propagation protocol tailored specifically for A. pelegrina to facilitate its large-scale propagation and promote the preservation of this vulnerable geophyte. In our experiment, explants obtained from in vitro germination were used. These explants were then cultured on a Murashige and Skoog (MS) medium solidified with agar (6 g L⁻¹) and supplemented with 2.22 μM 6-Benzylaminopurine (BAP) and 30 g L⁻¹ sucrose. The results indicated an average of 4.6 new shoots produced per initial explant. The implementation of light-emitting diode (LED) illumination with a red:blue ratio of 3:1 and 2.22 μM BAP resulted in an average shoot length of 6.2 cm. For rhizome induction, the addition of either 5.37 μM 1-naphthaleneacetic acid (NAA) or 5.37 μM indole-3-butyric acid (IBA) resulted in average rhizome lengths of 1.9 cm and 1.7 cm, respectively, with fresh weights of the vitroplants ranging from 2.9 g to 3.1 g, and rooting percentages between 100% and 96%, respectively. Notably, the survival rate of rooted plants obtained through in vitro propagation was 90% after a 4-week acclimatization period in a cold greenhouse, indicating the efficacy of the developed protocol for mass propagation and conservation efforts of this vulnerable geophyte species.