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The aim of this study was to evaluate the organogenic potential of Brazilian sugarcane varieties, in addition to verifying the in vitro multiplication rate and genetic stability by flow cytometry over monthly and consecutive subcultures. For that, stem apexes of twenty-two varieties were collected in field conditions and taken to the laboratory where external layers of leaves were removed. After surface sterilization, the innermost portion of the stem segment was sectioned and placed in a MS medium supplemented with 5.0 mg L−1 of NAA and 0.5 mg L−1 of KIN. For the multiplication rate, ten varieties were selected and inoculated in MS medium of liquid or semi-solid consistency plus 0.10 mg L−1 of KIN and 0.20 mg L−1 of BAP. Subcultures were performed every 30 days for a period up to 8 months. Genetic stability was verified by flow cytometry every two subcultures. At the end of the experiment, the sprouts were rooted and acclimatized in a greenhouse. As a result, it was observed that the regeneration occurred both by direct and indirect organogenic pathway. The varieties of sugarcane differed significantly regarding the regeneration capacity and amount of adventitious shoots formed. In multiplication, a significant interaction was observed between variety, consistency of the culture medium and number of subcultures. In general, in the first subcultures, the liquid consistency medium presented similar or superior results when compared with the semi-solid medium, however, from the fourth subculture, the semi-solid medium was superior. Morphological variations were verified from the fourth subculture. In addition, in some varieties, small changes in the relative amount of DNA were detected by flow cytometry. Sprouts of normal-looking sugarcane were successfully rooted and plantlets acclimatized after the eighth subculture. [ABSTRACT FROM AUTHOR]

Many important crops have cultivars with different ploidy and provide a diverse choice of materials for breeding programs. Therefore, it is essential to accurately assess the ploidy of all breeding materials. Increased DNA content is known to have various effects on external and internal morphology, an effect known as the "nucleotypic effect". Thus, anatomical assessment can be used as a tool for determining ploidy in plants, making the chromosome counting technique or flow cytometry unnecessary. This study aimed to evaluate the leaf anatomical characteristics of banana cultivars and understand the relationship between these features and ploidy levels. Thirteen accessions were evaluated, including diploid, triploid, and tetraploid genotypes, and cultivars, resulting from in vitro propagation after 90 days of acclimatization. Five fully expanded young leaves were collected from each cultivar, fixed in FAA70 (formaldehyde-acetic acid-ethanol) and preserved in 70% alcohol. Transverse and paradermal sections of the abaxial and adaxial regions were taken, and variables such as size and stomatal density, leaf thickness in the midrib and fourth vascular bundle region, and thickness of the epidermis, hypodermis, and parenchyma were measured. Results for leaf thickness, stomatal size, and density proved to be appropriate parameters for characterizing banana ploidy levels. [ABSTRACT FROM AUTHOR]

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Copyright of Agrociencia is the property of Colegio de Postgraduados and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)