Nicacio Cruz-Huerta’s research while affiliated with CP Kelco and other places

Rhyncholaelia glauca (Lindley) Schlechter, incluida en la CITES (Convención sobre el Comercio Internacional de Especies Amenazadas de Fauna y Flora Silvestres), es una orquídea epífita mexicana de extraordinario potencial florícola y genético. Las técnicas de cultivo de tejidos vegetales in vitro brindan una alternativa viable para la preservación y multiplicación a gran escala de especies amenazadas. El propósito de esta investigación fue establecer un protocolo para la inducción de organogénesis directa de brotes a partir de plántulas germinadas in vitro. El proceso comenzó con la germinación de semillas provenientes de una cápsula madura y cerrada. La organogénesis se evaluó en medio MS 100 % con 6-benciladenina (BA, 1.0-3.0 mg L-1) y ácido 1-naftalenacético (ANA, 0.25 y 0.5 mg L-1) con carbón activado (1.0 g L-1). En multiplicación, los brotes (1.5-2 cm) se cultivaron en medio MS (50 y 100 %) con BA (2.0-3.0 mg L-1) y ANA o ácido indolacético (AIA, 0.5 mg L-1) con carbón activado (0.5 g L-1). En alargamiento se colocaron grupos de brotes en medio MS (50 y 100 %) con o sin carbón activado (0.5 g L-1). Los ensayos se colocaron en un diseño experimental completamente al azar y se utilizó el análisis de varianza para analizar los datos. El mayor porcentaje de germinación (90.48 %) se obtuvo con medio MS 50 % sin reguladores de crecimiento. La mayor cantidad de brotes en inducción (2.48) y multiplicación (3.10) se consiguió con 2.5 mg L-1 de BA combinada con 0.5 mg L-1 de ANA, y 3.0 mg L-1 de BA combinada con 0.5 mg L-1 de AIA, respectivamente. La mayor longitud de brotes fue de 1.2 cm en medio MS 50 % adicionado con 0.5 g L-1 de carbón activado. El conocimiento generado en esta investigación ofrece una alternativa de propagación para el uso sostenible de Rhyncholaelia glauca con el fin de contrarrestar su estatus de vulnerabilidad.

Global warming has increased the stress conditions faced by natural populations of forest species. Genetic variation (GV) and phenotypic plasticity (PP) of adaptive traits are the main mechanisms by which these species survive the in situ effects of environmental fluctuation including a higher frequency of stressful events. This study evaluated the level of GV and PP in annual shoot growth and bud phenology traits such as bud flush and bud set date in 44 families of Pinus pseudostrobus from central Mexico established in an open-pollinated progeny trial replicated at two sites with different soil and climate conditions. Results showed wide GV in seasonal shoot growth pattern and strong genetic control in bud phenology traits. Shoot growth, particularly activation and formation of terminal bud, and shoot growth during wintertime, showed an adaptive relationship with climate conditions of origin site of families, particularly with moisture availability and aridity index. Despite the significant effect of test site on shoot growth, families exhibited consistent performance across sites for most traits, except for wintertime shoot growth (WSG) which showed a significant genotype x environment interaction. PP in WSG showed moderate genetic control and positive relationship with productivity (total height). The adaptive value of the GV and PP of shoot growth traits could allow P. pseudostrobus populations to mitigate the negative impacts of environmental fluctuations associated with global warming and provide competitive advantages in productivity for domestication purposes.

Agave salmiana Otto ex Salm-Dyck is sexually reproduced by seeds and asexually by aerial bulbils and offshoots from the rhizomes; however, this species is monocarpic, and the number of offshoots is small. Therefore, this research aimed to evaluate the number, height and diameter of rosette of offshoots from the rhizome of A. salmiana plants exposed to different treatments. In 2021, 240 plants of A. salmiana were randomly selected from a plantation in Temascalapa, State of Mexico, Mexico, and eight treatments were applied: control, IBA (indole-3-butyric acid), watering basin, hilling, watering basin-hilling, watering basin-IBA, hilling-IBA and hilling-watering basin-IBA, with 30 replications in a completely randomized design. Between July and November 2021 the number of offshoots was recorded monthly, and the last record was made in May 2022. Survival, height and rosette diameter of the offshoots were measured in November 2022 (17 months after the treatments were applied). Significant differences were found between treatments for the number of offshoots, height and rosette diameter. The average number of offshoots per plant was 2.4 with 99 % of survival, and the average values of height and rosette diameter were 14.5 and 15.9 cm, respectively. The plants in the control group developed 1.4 offshoots on average, while the plants in the watering basin-IBA produced 3.7 offshoots. The height of offshoots ranged between 13.2 cm in the watering basin treatment and 16.0 cm in the watering basin-IBA. The rosette diameter varied between 14.3 cm in the control group and 18.3 cm in the watering basin-IBA treatment. Cultural practices in combination with IBA increased the number of offshoots from the rhizome and positively influenced the height and diameter of the rosette.

A common garden trial with 18-month-old trees from 64 half-sib families of Pinus patula was established to identify genetic variation in growth and survival in response to drought for four months (November 25, 2020 to March 25, 2021, winter). A split-plot design with two moisture levels (Irrigation S0 = 40 – 55 % and Drought S1 = 20 – 39 % volumetric moisture) was used in large plots and families in small plots. At the beginning and end of the trial, the height (HT), diameter of the base (DB), and number of whorls and branches were determined, and the absolute (AGR) and relative (RGR) growth rates in HT and DB were calculated. Differences were found between the moisture levels during growth. Survival was 71 % in S0 and 60 % in S1. In S1, AGR in HT and DB was affected by 52 and 38 %, and RGR by 46 and 32 %, respectively, with respect to S0. In S0, 31.4 % of the plants formed one whorl and 2.1 % two, in S1 only 13.4 % and 0.2 % did. Genetic control was moderate in the joint environments with h2 i between 0.03 and 0.17 and h2f between 0.15 and 0.53. The performance of the families between the two humidity conditions was stable (rB from 0.71 to 1.0) in all variables, with greater genetic variation in S0 than in S1. Moderate genetic variability was observed in the growth of Pinus patula families under water restriction.

The objective of this work was to evaluate the photosynthetic response of citrus varieties to the inoculation of isolates T30 and T3 of Citrus tristeza virus (CTV) characterized as having potential to provide cross-protection against severe CTV isolates in citrus. Citrus plants of 'Campbell' orange, 'Persian' lime, and 'Key' lime were subjected to inoculations by both isolates by patch. Noninoculated plants were used as the control. Symptom expression, photosynthetic and transpiration rates, and stomatal conductance were evaluated by IRGA. Stomatal density and size were evaluated by epidermal impressions. The CTV isolates were also evaluated and molecularly characterized by RT-PCR and Sanger sequencing. 'Campbell' orange and 'Persian' lime plants remained asymptomatic after the inoculations. The inoculation treatments with both CTV isolates did not reduce photosynthetic capacity, transpiration rate, and stomatal conductance, in comparison with the control. Stomatal density and size varied according to the citrus species. T30 and T3 do not affect the photosynthetic responses of 'Campbell' orange and 'Persian' lime; therefore, these isolates have the potential to provide cross-protection to citrus varieties against severe isolates of CTV.

Prosthechea vitellina (Lindley) W.E. Higgins is an epiphytic orchid endemic to Mexico with ornamental and economic value; it is subject to special protection by NOM-059-SEMARNAT-2010 due to illegal trade and destruction of its habitat. In vitro plant tissue culture is an option for rescue, conservation and massive propagation of endangered species. The aim of the present study was to determine optimal in vitro conditions to regenerate plants by direct organogenesis and acclimatize them. The process started with germinated seedlings in vitro, and in successive stages the concentration of salts of the Murashige-Skoog medium (MS, 50 and 100 %), activated charcoal, 6-benzyl adenine (BA, 1.1-2.2 mg L-1), naphthaleneacetic acid (ANA, 0.19-0.38 mg L-1), indoleacetic acid (IAA, 0.18-0.36 mg L-1) and indole butyric acid (IBA, 0.52.0 mg L-1). In the acclimatization stage, 5 and 7-cm in vitro rooted plants were evaluated on different substrates. The experiments were established in a completely randomized design and the data obtained were subjected to ANOVA. At the induction stage, the largest number of shoots (2.03) were obtained with 2.2 mg L-1 of BA and 0.19 mg L-1 of ANA. At multiplication, 2.5 shoots were produced with 1.0 mg L-1 of BA and 0.25 mg L-1 of IAA at eight weeks of culture. The largest elongation of shoots (2.16 cm) was achieved with MS 50 % and 0.5 g L-1 of activated charcoal. At rooting, the largest number of roots occurred with 2.0 mg L-1 of IBA, generating 5.27 roots per plant. In acclimatization, survival was 100 %, with 7-cm plants on pine bark. The developed protocol provides a method for the propagation of this orchid for rescue, conservation, reintroduction and commercial use.

Lycaste aromatica (Graham) Lindl. orchid is known for its outstanding cinnamon aroma, which has caused its illegal and accelerated extraction from its natural habitat. For this reason, procedures were developed for asymbiotic seed germination and seedling development in a gravity immersion bioreactor (GIB) system. Four culture media were tested for in vitro germination: ½ Murashige and Skoog (MS) containing 15 g L−1 sucrose, MS, ½ Knudson C containing 15 g L−1 sucrose, and Knudson C. The efficiency of in vitro culture protocol using semi-solid medium was compared to four immersion frequencies of the GIB system in a liquid medium using 30 mL of ½ MS medium per seedling. Germination began at 8 wk and lasted for 6 wk. The best treatment was ½ MS with 81% seed germination. In 90 d, the GIB did not result in significant effects on most growth parameters, including number of leaves; number of roots and seedling height were not significantly different to those of seedlings developed in the semi-solid medium. However, seedlings developed in the semi-solid medium reported a higher number of shoots (1.6 shoots) and root length (2 cm). The GIB showed the highest photosynthesis rate (0.74 μmol CO2 g−1 s−1). The GIB could be an alternative to develop this species due to its increased photosynthesis and having stomatal function.

The orchid Lycaste aromatica (Graham) Lindl. is known for its outstanding cinnamon aroma, which has caused its illegal extraction from its natural habitat. For this reason, procedures were developed for the asymbiotic seeds germination and seedlings development in a gravity immersion bioreactor (GIB) system. Four culture media were tested for in vitro germination: ½ Murashige and Skoog (MS), MS, ½ Knudson C 15 g L − 1 sucrose, Knudson C. The efficiency of the in vitro culture protocol using the semi-solid medium was compared and with four immersion frequencies of the GIB system in a liquid medium, using 30 mL of ½ MS medium per seedling. Germination began at eight weeks and lasted for six weeks. The best treatment was ½ MS with 161 germinated seeds. In 90 days, the cultures in bioreactors reached significant differences in the number of leaves (10 leaves), number of roots (4.7 roots), and seedling height (5.4 cm). However, the seedlings developed in the semi-solid medium reported a higher number of shoots (1.6 shoots) and root length (2 cm); furthermore, the bioreactor culture showed the highest photosynthesis rate (0.74 µmol CO 2 g − 1 s − 1 ). The culture system in bioreactors is an excellent alternative to develop this species because it increases photosynthesis and the size of the seedlings, which favor their acclimatization.

Introduction: In Pinus radiata D. Don, one of the most widely planted pines globally, frost damages plantations at the seedling stage. Objective: To determine differences in growth and tolerance to low temperatures of native populations (Guadalupe and Cedros islands) of P. radiata in greenhouse and outdoors conditions, under different levels of soil moisture. Materials and methods: Low-temperature tolerance was determined through the damage index (DI) in freezing tests at -12 °C during 4 h. In each environment (greenhouse and outdoors) two soil moisture treatments were defined (irrigation and drought). The DI was evaluated with the method of electrical conductivity in primary needles during winter and spring. The absolute growth rate (AGR) of the terminal shoot was obtained by measuring the total height of the seedlings. Results and discussion: Average DI of 50 and 64 % were obtained in winter and spring, respectively. In greenhouse, DI was different (P ≤ 0.05) between populations, being higher in Guadalupe (>59 %) than in Cedros (<42 %), both in winter and spring. Outdoors, Cedros (64.1 %) had a higher DI than Guadalupe (36.5 %) only during winter. DI was similar in both favorable soil moisture and drought conditions. The Guadalupe population presented higher AGRs in both environments and moisture conditions. Conclusion: The population of Guadalupe is more sensitive to low temperatures with greater variation in DI, due to its growth dynamics. Differences between populations are useful in the genetic improvement of the species.