ABSTRACT Physical mutagenesis with 60Co is a technique used in plant breeding to induce desired phenotypic characteristics. This research objective was to evaluate physical and physiological quality and protein content of jalapeño pepper (Capsicum annuum L.) seeds from plants that were selected as tolerant to water stress, these plants were derived from seeds irradiated with 60Co at 100 Gy dose (T1P2 and T1P5 both from tolerant plants to water stress). Control seeds were significantly superior to the mutants in the variable standard germination (90.66%), standard germination with accelerated aging (57.3%), normal seedlings (95.6%), 1000 seeds weight (6.349 g), hectoliter weight (51.97 kg hL-1) and radicle dry weight (18 mg). Mutant seeds were significantly superior to control seeds in seed length and width (4.356 mm in T1P2 and 4.256 mm in T1P5 for length; 3.544 mm in T1P2 and 3.632 mm in T1P5 for width). In seed thickness tests, germinated seeds aerial part fresh and dry weight, radicle fresh weight, the two mutants seed types and the control were significantly equal. In seed storage proteins content, T1P2 treatment had a higher globulins concentration. In the prolamin fraction, the two mutant seed types were superior to control. T1P5 treatment seeds had the highest glutelins concentration. Mutant seeds showed different characteristics as compared to control in physical, physiological and plantlet parts weight components.

ABSTRACT In recent years, benefits of silicon in plants grown under stress conditions have been reported. The objective of the research was to evaluate the response at a physiological and biochemical level of millet (Panicum miliaceum L.) to fertilization with Si under controlled stress conditions during vegetative stage, drought, salinity and the control (without stress). After stress, shoot and root length, DM content, peroxidase (POD) and catalase (CAT) activity, proline, H2O2 and Si content, seed yield and germination percentage were measured. Drought and salinity significantly decreased shoot (24%, 21%) and root (30% in drought) development, weight (36%, 29%) and seed number (30%, 21%) per plant. Application of Si significantly increased seed number (289) and seed weight (1.20 g) in the control plants, increased seed weight (0.83 g) in plants under drought and germination percentage (99%) in plants under salinity. Silicon increased 2.1 times POD activity in drought, 1.4 times in salinity and control plants; CAT activity increased 10.6 times in salinity and 1.7 times in control plants. Silicon decreased 10 times proline levels in plants under drought; in salinity and control, proline content increased 1.3 times with Si and H2O2 levels decreased in these treatments. The Si content in plants fertilized with Si under drought, salinity and control was 6%, 3.54% and 5.45% respectively. In conclusion, Si can improve plant stress tolerance by stimulating POD and CAT activity, and regulating proline levels, allowing it to improve the production and physiological seed.

ABSTRACT The Trichoderma harzianum fungus is one of the most widely used biological control agents in agriculture. A new T. harzianum THITR01 strain was isolated and their spores were mutagenized with ethyl methane sulfonate obtaining 174 mutants. M7, M14, M21 and M24 are mutant strains that showed 97.4%-100% antagonist effect against Sclerotium rolfsii, Rhizoctonia solani and Sclerotinia sclerotiorum compared to the wild strain. Under potato dextrose agar (PDA) medium with either NaCl, sorbitol or NaHCO3 there were nonsignificant growth rate differences between the mutants and the wild strain. M14 and M21 mutant strains were inoculated on ‘Jalapeño’ pepper plants (Capsicum annuum L. var. annuum) with unavailable P promoted a significant increase in root fresh weight (54% and 40%, respectively) and dry weight (28% in both strains), compared to plant inoculation with the wild strain. The M14 strain presented the highest P solubilization ability (13.4 μg g-1) in the substrate and promoted a change on root architecture. There was a higher relative water content (82.9%) in drought stressed plants inoculated with the M24 mutant than in plants that were inoculated with the wild type strain (76.3%), and also higher levels of proline in chili pepper plants inoculated with the M24 mutant (939.5 μg g-1 dry weight) than in plants inoculated with the wild type strain (419.8 μg g-1 dry weight). Therefore, M14, M21 and M24 mutant strains could potentially be used as biocontrol agents and plant protector from abiotic stress.

Abstract The Drymifolia avocado variety (Persea americana Mill.) is generally used as rootstock, so it is important to implement somatic embryogenesis and in vitro organogenesis techniques for its genetic improvement, conservation and clonal propagation. In this work, direct and indirect somatic embryogenesis and organogenesis of the Drymifolia variety were evaluated. Germination of the mature somatic embryos was induced with 0.5 mg L-1 of 6-N-benzyl amino purine (BAP) and 1 mg L-1 of gibberellic acid (GA3). Of the six accessions evaluated, Celaya 79, Comonfort 53, San Miguel, BG24, BG181 and Zutano, only San Miguel responded to the embryogenesis process. In direct embryogenesis, the highest regeneration efficiency was obtained with 0.2 mg L-1 of picloram (46%) and 10 mg L-1 of ANA (40%). In indirect embryogenesis, the San Miguel accession formed callus with 0.2 mg L-1 of picloram and had a regeneration efficiency of 45%, conserving its regeneration potential for up to six months. Regarding organogenesis, decapitated immature zygotic embryos were cultured in medium with or without growth regulators and all six accessions responded positively to both conditions. The Comonfort 53 accession had higher regeneration efficiency (54%) with growth regulators. This study carried out from 2016 to 2018, provides a new and promising approach for the regeneration and multiplication of P. americana var. Drymifolia through zygotic embryos.

Resumen La variedad Drymifolia de aguacate (Persea americana Mill.) es usada generalmente como portainjerto por lo que es importante implementar las técnicas de embriogénesis somática y la organogénesis in vitro para su mejora genética, conservación y propagación clonal. En este trabajo se evaluaron embriogénesis somática directa, indirecta y organogénesis de la variedad Drymifolia. La germinación de los embriones somáticos maduros se indujo con 0.5 mg L-1 de 6-N-bencil amino purina (BAP) y 1 mg L-1 de ácido giberélico (GA3). De las seis accesiones evaluadas, Celaya 79, Comonfort 53, San Miguel, BG24, BG181 y Zutano, solo San Miguel respondió al proceso de embriogénesis. En la embriogénesis directa la eficiencia más alta de regeneración se obtuvo con 0.2 mg L-1 de picloram (46%) y 10 mg L-1 de ANA (40%). En la embriogénesis indirecta la accesión San Miguel formó callos con 0.2 mg L-1 de picloram y tuvo una eficiencia de regeneración de 45% conservando su potencial de regeneración hasta por seis meses. Con respecto a la organogénesis, se cultivaron embriones cigóticos inmaduros decapitados en medio con reguladores de crecimiento o sin ellos y las seis accesiones respondieron positivamente a ambas condiciones. La accesión Comonfort 53 tuvo mayor eficiencia de regeneración (54%) con reguladores de crecimiento. Este estudio realizado del 2016 a 2018, proporciona un enfoque nuevo y prometedor para la regeneración y multiplicación de plantas de P. americana var. Drymifolia a través de embriones cigóticos.

ABSTRACT Drought is one of the most limiting factors in agricultural production worldwide. The aim of this work was to evaluate the per se response to drought stress of three maize (Zea mays L.) semi-inbred lines (CHIH, COAH, and ARZM) during the anthesis and grain filling stages. These semi-inbred lines (BC1S1) are S1 offspring of crosses between drought-tolerant maize and a high-yield line bred by the Centro Internacional de Mejoramiento de Maíz y Trigo (CIMMYT). Materials were evaluated during a 15-d controlled drought and post-drought irrigation reestablishment period. The photosynthetic rate decreased by 50% in CHIH during drought and it recovered after stress was removed. Proline levels increased 2.3 times in COAH during stress and nonsignificant increases were observed in ARZM or CHIH. However, glycine betaine accumulated at 1061-1133 ng mg-1 fresh weight (FW) before stress, but decreased to 879-1000 ng mg-1 FW during drought stress. The trehalose concentration increased 1.8 times in ARZM (5.60 ng mg-1 FW) under drought stress and remained at similar levels in CHIH (6.48 ng mg-1 FW) and COAH (8.63 ng mg-1 FW) before and during drought stress. In contrast, trehalose-6-phosphate decreased 33% to 38% under drought stress in all three BC1S1 entries and recovered its initial levels after irrigation. Grain biomass loss under drought stress was 54% for ARZM, 48.2% for COAH, and only 26.5% for CHIH. These results showed that CHIH, COAH, and ARZM are drought-tolerant and suggest that osmoprotectant accumulation might play a key role in their physiological performance and grain biomass trait.

Abstract Chia is a very valuable resource since it is the main source of unsaturated fatty acids, mainly α-linolenic, in addition to protein and fiber. In this investigation, seven collections were made in seven locations for study and comparison. Seed size were measured, thousand seed weight, volumetric weight, color, germination percentage and oil extraction for chromatography analysis. The collection of cultivated chia from Guanajuato showed greater variability in seed size and that of Roque la minor. The wild collections had the smallest seed size. The cultivated one of Guanajuato has the greater weight in seed and the wild ones the minor, the latter did not germinate, but the domesticated ones did. There were no differences in volumetric weight; however, there were differences in chromatograms (HPLC) and in physical characteristics and color variation in domesticated ones, including white seeds. This prospective research shows that the variability present in wild and cultivated chia can be used for plant breeding.

Resumen La chía es un recurso muy valioso ya que es la principal fuente de ácidos grasos insaturados, principalmente α-linolénico, además de proteína y fibra. En esta investigación se realizaron siete colectas en siete localidades para su estudio y comparación. Se midió tamaño de semilla, peso de mil semillas, peso volumétrico, color, porcentaje de germinación y extracción de aceite para análisis en cromatografía. La colecta de chía cultivada de Guanajuato presentó mayor variabilidad en tamaño de semilla y la de Roque la menor. Las colectas silvestres tuvieron el menor tamaño de semilla. La cultivada de Guanajuato tiene el peso mayor en semilla y las silvestres el menor, estas últimas no germinaron, pero sí lo hicieron las domesticadas. No hubo diferencias en peso volumétrico; sin embargo, si hubo diferencias en los cromatogramas (HPLC) y en las características físicas y variación de color en las domesticadas, incluidas semillas de color blanco. Esta investigación prospectiva muestra que la variabilidad presente en la chía silvestre y cultivada puede ser aprovechada para el fitomejoramiento.

Less than 0.5% of total water in the world is available for human consumption and agriculture. The major part of the world's water is saline and salinity in soils interferes in germination of seeds and the posterior development of the plant. In order to increase the osmotolerance of tomato, seedlings were associated with Azospirillum brasilense Cd, Azospirillum brasilense Cd transformed bacteria with a plasmid harboring a trehalose biosynthesis gene-fusion or Chlorella vulgaris. Two plant culture media: Hydroponic and Murashige and Skoog were tested. In the first set of studies seedlings were associated to single free cells meanwhile in a second set single and combined free cells were studied. A positive interaction between transformed Azospirillum and Chlorella vulagris and tomato plants was observed. Seedlings showed a salt concentration tolerance, as sodium chloride, up to 200 mM. According to our results, the association of plants with A. brasilense Cd-BIF and C. vulgaris is a viable approach to increase their salt tolerance and biomass, as consequence the possible use of sea water to irrigate horticultural plants.