Agricultural biodiversity includes many species that have biological variants (natives, ecotypes, races, morphotypes). Their use is restricted to local areas because they do not fulfill the commercial requirements; however, it is well documented that these species are a source of metabolites, proteins, enzymes, and genes. Rescuing and harnessing them through traditional genetic breeding is time-consuming and expensive. Inducing mutagenesis may be a short-time option for its genetic improvement. A review of outstanding research was carried out, in order to become familiar with gene breeding using gamma radiation and its relevance to obtain outstanding agronomic characteristics for underutilized species. An approach was made to the global panorama of the application of gamma radiation in different conventional crop species and in vitro cultivated species, in order to obtain secondary metabolites, as well as molecular tools used for mutation screening. The varied effects of gamma radiation are essentially the result of the individual responses and phenotypic plasticity of each organism. However, even implicit chance can be reduced with specific genetic breeding, environmental adaptation, or conservation objectives.

El objetivo de este trabajo fue estimar el grado de variación genética dentro del complejo infraespecífico de Sechium mediante el uso de sistemas isoenzimáticos. Se analizaron 23 loci codificados por 12 sistemas isoenzimáticos, en geles de almidón, en 10 individuos de cada una de las 30 accesiones (27 cultivadas y tres silvestres). La variación genética se estimó con base en el número promedio de alelos por locus (NPAL), porcentaje de porlimorfismo (PP), heterocigosidad observada y esperada (Ho y He), índice relativo de heterocigosidad (IRH) e índice de Shannon (IS). Para NPAL y PP, el promedio para las 30 accesiones fue de 2, 03 y 59, 8%, respectivamente. El análisis de Ho y He mostró variación genética en el complejo infraespecífico de Sechium, con valores promedio de 0, 05 y 0, 26, respectivamente. El IRH mostró una deficiencia de individuos heterocigotos (promedio de -0, 75). El IS mostró gran diversidad en las 30 accesiones (0, 41). Las poblaciones con mayor diversidad fueron Negrito, Verde liso, Negro xalapa, Verde espinoso y Negro cónico; con una variación intermedia fueron Castilla blanco, Caldero y Blanco pequeño; y, con poca variación, Castilla verde, Cambray y los parientes silvestres.

Paulownia elongata es una especie forestal de origen oriental y rápido crecimiento, que fue introducida en México a finales de 1998 para ser incorporada en plantaciones comerciales maderables, pues su madera es ligera, por lo cual se emplea en la manufactura de muebles, artesanías, instrumentos musicales y en el acabado de interiores. El objetivo de este trabajo fue determinar las mejores condiciones de cultivo in vitro, para la regeneración de plántulas de P. elongata a partir de diversos tipos de explantes de segmentos internodales, foliares y peciolares, lo que derivó en un protocolo para organogénesis directa apto para usarse en sistemas de transformación genética. En todos los casos el medio Murashige y Skoog (MS) fue adicionado con 6-benciladenina (BA) y ácido naftalenacético (ANA), en distintas concentraciones. Se obtuvo respuesta en la totalidad de los explantes con la combinación de 5 mg L-1 de BA y 1.0 mg L-1 de ANA; sin embargo, los segmentos internodales mostraron una mejor inducción de brotes: 83% de explantes con brotes y 1.52 brotes por explante con la combinación de 4 mg L-1 de BA y 0.2 mg L-1 de ANA, a diferencia de los segmentos de pecíolo que produjeron sus mejores resultados de 53% de explantes con brote y 0.62 brotes por explante, con una mezcla de 7 mg L-1 de BA y 0.2 mg L-1 de ANA.

Micro-grafting and mini-grafting trials were carried out in order to obtain complete Pinus patula plants generated in vitro, derived from the fact that the formation of roots in micro-propagated shoots is very low or null. On the other hand, there is the possibility of generating clones with outstanding genetic characteristics. P. patula seeds were established in aseptic conditions and geminated in vitro in DCR medium; the aerial part was dissected from the base and roots were kept in DCR medium added with 0.5 mg l-1 of NAA to maintain them and served as mini rootstock, the shoots were transferred to DCR medium added with 2.0 mg l-1 of BA to form seedlings with an average of 3.9 shoots per explant at 30 days. On the other hand, 2-month-old nursery seedlings were used as rootstock for the mini-grafts. For the micro-graft tests, the shoots obtained were taken and the apical meristems with approximately 5 mm were isolated to conduct micro-grafting at the base with roots, and in the case of mini-grafts the shoots generated were allowed to grow to a length of 3 cm on average and grafted onto nursery seedlings. In both cases, the achievement of the grafted materials and the length were evaluated to measure the growth of the materials that had positive success. The response of micro-grafts was very low, 10% success, in addition to the manipulation of the meristems being very complex, which generated oxidation in the tissues. On the contrary, the mini-grafts showed 93.3 of grafting success and average growth of 26.05 cm, two months after the grafting process

Objective: The most appropriate conditions for genetic transformation through direct (bioballistic) and indirect (Agrobacterium tumefaciens) transformation systems in Paulownia elongata were established. Design/methodology/approach: Starting from in vitro propagation through both direct and indirect organogenesis, internodal stem segments with 0.5 to 1 cm length were determined as the best explant. The optimum dose for selection media was determined to be 15 mg L-1 of kanamycin. It was possible to obtain transgenic plants under both transformation systems. In the case of Agrobacterium tumefaciens, two hours of incubation, 48 h of co-cultivation, and optical density of 0.9 were used; while for bioballistics, the best conditions were 120 PSI of shot pressure, shot height at level 6 (16 cm), and vacuum pressure of 22 Hg mm, with particle inflow gun system (PIG). Results: Both systems produced complete transformants, chimeras, as well as those confirmed by histochemical X-GLUC and PCR analysis, producing a total of 14 positive plants by A. tumefaciens transformation from 26 trials and ten positive plants by the bioballistic system from 30 trials; a construction with chitinase and glucanase, NPT II selection gene and the GUS reporter gene were used. Findings/conclusions: So far, this has been the first report including integration of chitinase and glucanase genes.