Andrés Cruz-Hernández

PLANT REGENERATION OF AGAVE TEQUILANA BY INDIRECT ORGANOGENESIS

SummaryIndirect organogenesis was developed in Agave tequilana. Leaf segments and meristematic tissue from the central head (‘piña’) were evaluated as explant sources. A minimal-sized explant with high bud-forming capacity (19.5 BFC) was obtained through a cross section of meristematic tissue from in vitro plantlets. In callus culture, the best growth response was due to naphthalene acetic-acid (NAA) presenting a contrasting response compared to 2,4-dichlorophenoxyacetic acid (2,4-D). Regeneration from meristem segments and callus was obtained using 1.1 μM 2,4-D and 44 μM 6-benzylaminopurine (BA). The regeneration capacity of callus was maintained for 3 mo. Shoots regenerated were rooted in a hormone-free MSI medium and acclimatized in a greenhouse with a 100% survival.

Plant regeneration of three Opuntia genotypes used as human food

In vitro micropropagation Opuntia cactus plants, whose young stems are consumed as vegetables, is reported. Cladode explants from three Opuntia genotypes, were cultivated in MS medium containing BA and GA3. Shoots produced were used as secondary explants and BA added at different concentrations to induce shoot development. 0.5 μM BA was the best for bud formation. Satisfactory rooting occurred when IBA was added to the medium, and plants were successfully established in soil and adapted to greenhouse conditions. The protocols developed in this work provide a basis for the establishment of a genetic transformation system for Opuntia spp.

Modification of the amaranth 11S globulin storage protein to produce an inhibitory peptide of the angiotensin I converting enzyme, and its expression in Escherichia coli.

Amarantin is the predominant seed storage protein from amaranth. It shows a high content of essential amino acids, making this protein important from a nutritional viewpoint. The protein has two disulfide linked subunits: acidic and basic. Acidic subunit has the potential as a functional and nutraceutical protein, and it is structurally a good candidate for modification. In order to improve its functionality, the primary structure was modified in the third variable region of globulins 11S, by inserting four Val-Tyr antihypertensive peptides in tandem. The designed plasmid was expressed in Escherichia coli Origami (DE3) and then the expressed protein was purified. Mass spectrometry analysis was used to corroborate the identity of the protein by peptide mass fingerprinting; also, the modified peptide was fragmented and sequenced by mass spectrometry, corroborating thus the inserted residues. The hydrolyzed protein showed a high inhibitory activity of the angiotensin converting enzyme (IC(50) 0.064 mg ml(-1)); it was nearly eightfold more active than the nonmodified protein. In spite that the nonmodified subunit is less active, its activity is comparable with other hydrolyzed proteins reported as high active inhibitors. The expressed and purified subunit after its engineered modification, may be useful for preventing hypertension and for other medical purposes.

Isolation of functional RNA from cactus fruit

Isolating RNA from cactus fruit is notoriously difficult because the fruit contains high amounts of secondary metabolites and polysaccharides. These form insoluble complexes with nucleic acids during extraction and can inhibit enzyme action. Our procedure allows for the extraction of RNA from finely ground tissue. The RNA we isolated was of high quality and undegraded, as gauged by spectrophotometry and electrophoresis in agarose gels. Quality was further assessed through use of the RNA in RT-PCR and northern blot analysis, indicating that it could be used to construct cDNA libraries. Using this modified protocol, 90μg of RNA was routinely obtained from 1 g of dried cactus fruit. Isolating RNA from other polysaccharide-rich fruits was also possible.

Fruit Quality: New Insights for Biotechnology

At ripening fruits undergo many changes which include the development of color and aroma and improvements in flavor and texture that make them attractive to potential consumers. Fruits provide an important source of health-related substances, plus minerals and vitamins, and the quality of a fruit is influenced by variety, nutritional status, and environmental conditions during plant growth and fruit development. Ripening is considered to be the main process in fruit development, and all studies had been focused on this process which included physicochemical, biochemical, and molecular analysis. With the development of genomic analysis the strategies to study fruit ripening have been changing and now there are new perspectives and opportunities. The objective of this review is to describe the state of the art in the studies related to fruit ripening with emphasis in molecular studies.