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. The objective of this work was to estimate the degree of genetic variation in an infraspecific complex of Sechium using isoenzymatic systems. For this purpose, 23 loci were codified by 12 isoenzimatic systems and analyzed in starch gels, in 10 individuals from each of the 30 accesions of Sechium (27 cultivated and three wild relatives). The estimation of genetic variation was based on the average number of alleles per locus (NPAL), polymorphism percentage (PP), observed and expected heterozygosity (Ho and He), relative heterozygosity index (RHI) and Shannon´s index (IS). For NPAL and PP, the average for the 30 accesions was 2.03 and 59.8%, respectively. The analysis of Ho and He showed genetic variation in the infraspecific complex of Sechium, with 0.05 and 0.26 average values, respectively. The RHI showed a deficiency of heterozygote individuals (average of -0.75). The IS showed a great diversity in the 30 accesions (0.41). The populations with the greatest genetic variations were Negrito, Verde liso, Negro xalapa, Verde espinoso and Negro cónico; with intermediate variation were Castilla blanco, Caldero and Blanco pequeño; and with little variation were Castilla verde, Cambray and wild relatives

Sechium compositum (Cucurbitaceae) is a wild species that is distributed in the Soconusco region, Chiapas, Mexico, and the border with Guatemala. This species has an intangible biochemical value resulting from the pharmacological relevance of its secondary metabolites. However, as a consequence of the lack of knowledge about its importance, it is being displaced from its habitat at an accelerated rate, incurring the risk of genetic loss. Therefore, an in vitro culture protocol with two experimental phases was evaluated to propagate, conserve, and regenerate this species. The first phases considered the shoot propagation, adding seven concentrations (0.1, 0.2, 0.4, 0.6, 0.8, 1.0, 1.2 mg mL⁻¹) of 6-benzylaminopurine (BA) and thidiazuron (TDZ) and evaluating the number of buds and shoots and the shoot height. The best multiplication response was recorded with 0.1, 0.2, 0.4, and 1.0 mg L⁻¹ of BA and 0.1 mg L⁻¹ of TDZ, as well as the MS base culture medium. The validation of the results of the first phase (0.1 mg L⁻¹ of BA) was compared with the MS in an independent experiment against the control (n = 50 repetitions), obtaining a height of 52 mm, 1.36 shoots, and 9.22 buds, suggesting that this concentration is adequate for the purpose, surpassing the MS control (MS culture medium alone). Of the total volume of roots obtained with packed bud structure in the previous experimental sample, it was reduced to 14% (n = 50). The second phase consisted of inducing callus formation from stem and leaf explants through the addition of 0.5, 1.0, and 2.0 mg L⁻¹ of TDZ and 2,4-Dichlorophenoxyacetic acid (2,4-D) to the medium. Callus induction in S. compositum was better when using the stem in a medium with 2.0 mg L⁻¹ of 2,4-D with a value of 97.8% around the explant. The addition of 500 mg L⁻¹ of polyvinylpyrrolidone (PVP) is also suggested to reduce oxidation. This protocol represents a significant advance in the conservation, multiplication, and callus formation of S. compositum and contributes to its rescue and revaluation in the face of the danger of extinction.

Sechium compositum (Cucurbitaceae) is a wild species that is distributed in the Soconusco region, Chiapas, Mexico, and the border with Guatemala. This species has an intangible biochemical value resulting from the pharmacological relevance of its secondary metabolites. However, as a consequence of the lack of knowledge about its importance, it is being displaced from its habitat at an accelerated rate, incurring the risk of genetic loss. Therefore, an in vitro culture protocol with two experimental phases was evaluated to propagate, conserve, and regenerate this species. The first phases considered the multiplication of seedlings, adding seven concentrations (0.1, 0.2, 0.4, 0.6, 0.8, 1.0, 1.2 mg mL-1) of 6-benzylaminopurine (BA) and thidiazuron (TDZ) and evaluating the number of buds, shoots, and seedling height. The best multiplication response was recorded with 0.1, 0.2, 0.4, and 1.0 mg L-1 of BA and 0.1 mg L-1 of TDZ, as well as the MS base culture medium. With 0.1 mg L-1 of BA, 52-mm height, 1.36 shoots, and 9.22 buds were obtained, surpassing the MS control (MS culture medium alone); likewise, twice more roots (80%) and a 14% reduction in the bud structure were packed in 50 repetitions. The second phase consisted of inducing callus formation from stem and leaf explants through the addition of 0.5, 1.0, and 2.0 mg L-1 of TDZ and 2,4-Dichlorophenoxyacetic acid (2,4-D) to the medium. The results demonstrated that the induction of callogenesis in S. compositum has a better start from the stem in a medium with 2.0 mg L-1 of 2,4-D, whose value was 4.89 —equivalent to 97.8% callus formation around the explant. The addition of 500 mg L-1 of polyvinylpyrrolidone (PVP) is also suggested to reduce oxidation. This protocol represents a significant advance in the conservation, multiplication, and callogenesis of S. compositum and contributes to its rescue and revaluation in the face of the danger of extinction.

Seed germination is a key factor in the success of forest regeneration and nursery production; however, its performance depends on the interactions among seed physiology, pre-germination treatments, and environmental conditions. We evaluated how eight pre-germination treatments and two contrasting environments affected germination capacity, vigor, and kinetics in seed lots (provenances) of Pinus hartwegii, P. montezumae, and P. pseudostrobus. The seeds were subjected to hydration, H₂O₂, mechanical scarification, or GA₃ treatments and were germinated in a controlled chamber and a greenhouse; the responses were analyzed using generalized linear mixed models. Species × environment interactions were significant for all germination parameters. Final germination was higher in the greenhouse than in the chamber (81% vs. 72%), while germination was faster in the chamber. P. pseudostrobus achieved the highest germination rate (96%), P. montezumae showed the greatest stability across environments, and P. hartwegii exhibited a relatively stable final germination capacity across environments but greater kinetic sensitivity. Among the treatments evaluated, 2% H₂O₂ and 200 mg L⁻¹ GA₃ showed the most favorable balance between germination capacity and rate, while scarification accelerated germination but reduced its final percentage.