No abstract

A variabilidade genética de genótipos de alho mantidos em Bancos de Germoplasma tem sido bastante investigada com marcadores morfológicos e bioquímicos; porém, as informações obtidas com esses marcadores têm

Like many other species of trees native to the Brazilian Mata Atlântica (Atlantic Forest), the Myrtaceae, such as the Red Araza (Psidium cattleianum Sabine), are widely cited as arbuscular mycorrhizal formers. Nevertheless, recent studies show evidence that Myrtaceae from different tropical, subtropical and neotropical ecosystems can also prompt the formation of ectomycorrhizae, indicating that this species' ectomycorrhizal status should be further explored. Because of this, this research effort studied the in vitro interaction between the Red Araza and two ectomycorrhizal fungi isolates, belonging to the Pisolithus microcarpus (D17) and Scleroderma citrinum (UFSC-Sc133) species. An analysis was performed to determine the formation of ectomycorrhizal structures, or lack thereof, and the developmental differences between the in vitro mycorrhized and non-mycorrhized plants. The analysis proved that indeed an ectomycorrhizal association was developed between the Red Araza, and the D17 and UFSC-Sc133 isolates, a fact never before registered in the existing literature. After an in vitro period of 110 days, it was confirmed that the D17 and UFSC-Sc133 isolates formed mycorrhizal colonization of 91.6% and 15.7%, respectively. Furthermore, both isolates also promoted root thickening, and the formation of a fungal mantle and a Hartig net. However, when compared to the Control plants, the fungal isolates did not contribute to an increase in the development of the subject plants, possibly due to the specific experimental conditions used, such as a high humidity environment and high availability of nutrients in the symbiotic substrate.

Red Araza, or Red Strawberry Guava (Psidium cattleianum Sabine) is a native Brazilian Atlantic Forest species of the Myrtaceae family, whose seeds exhibit integumental dormancy. Due to its importance to different industries worldwide, recent research efforts are seeking to expand this species' micropropagation processes using in vitro seedling germination, especially since in vitro micropropagation of adult plant material has, so far, been limited. This research effort evaluated different methods of overcoming integumental dormancy during in vitro germination of the Red Araza, so as to allow future micropropagation of the species. The seeds' emergence and vigor were evaluated based on mechanical and acid scarification, using different substrates and immersions in solutions with different levels of gibberellic acid (GA 3 ), and on the influence of the pre-immersion of seeds in water and sulfuric acid. The mechanical and acid scarification of the seeds, combined or separate, resulted in higher in vitro germination percentages and a higher germination rate index (GRI). Pre-immersion in distilled water (20 hours) also proved to be efficient for the germination of the Red Araza seed, with 76.2% of the seeds germinating and a higher speed of emergence (GRI = 0.18). When compared to a Murashige and Skoog (MS-zero) medium, sowing in a hydrophilic cotton substrate showed greater emergence and vigor, with approximately 70% of the seeds germinating. Treating the seeds by pre-immersing them in GA 3 turned out to be unnecessary. The methods used for overcoming integumental dormancy during in vitro germination of Red Araza seeds proved to be efficient, and could be used to develop micropropagation protocols of seminal origin for this species.