Induced in vitro adaptation for salt tolerance in date palm (Phoenix dactylifera L) cultivar Khalas

BACKGROUND: Soil salinity causes huge economic losses to agriculture productivity in arid and semiarid areas world-wide. The affected plants face disturbances in osmotic adjustment, nutrient transport, ionic toxicity and reduced photosynthesis. Conventional breeding approaches produce little success in combating various stresses in plants. However, non-conventional approaches, such as in vitro tissue culturing, produce genetic variability in the development of salt-tolerant plants, particularly in woody trees. RESULTS: Embryogenic callus cultures of the date palm cultivar Khalas were subjected to various salt levels ranging from 0 to 300 mM in eight subcultures. The regenerants obtained from the salt-treated cultures were regenerated and evaluated using the same concentration of NaCl with which the calli were treated. All the salt-adapted (SA) regenerants showed improved growth characteristics, physiological performance, ion concentrations and K+/Na+ ratios than the salt non-adapted (SNA) regenerants and the control. Regression between the leaf Na+ concentration and net photosynthesis revealed an inverse nonlinear correlation in the SNA regenerants. Leaf K+ contents and stomatal conductance showed a strong linear relationship in SA regenerants compared with the inverse linear correlation, and a very poor coefficient of determination in SNA regenerants. The genetic fidelity of the selected SA regenerants was also tested using 36 random amplified polymorphic DNA (RAPD) primers, of which 26 produced scorable bands. The primers generated 1-10 bands, with an average of 5.4 bands per RAPD primer; there was no variation between SA regenerants and the negative control. CONCLUSION: This is the first report of the variants generated from salt-stressed cultures and their potential adaptation to salinity in date palm cv. Khalas. The massive production of salt stress-adapted date palm plants may be much easier using the salt adaptation approach. Such plants can perform better during exposure to salt stress compared to the non-treated date palm plants.

Embriogénesis no zigótica en Passiflora maliformis Nonzygotic / Embryogenesis in Passiflora maliformis

La importancia económica, ecológica y medicinal de las pasifloras ha fomentado el desarrollo de investigaciones multidisciplinarias en estas plantas. En cultivo in vitro, la embriogénesis no zigótica representa una alternativa para regeneración de plantas; no obstante, esta técnica ha presentado dificultades en la reproducibilidad de los protocolos, así como formación de ciertos embriones y plántulas anormales en algunas especies. En este estudio se evaluó la capacidad morfogénica de embriones zigóticos maduros (EZM) de Passiflora maliformis L para desarrollar embriones no zigóticos (ENZ), y posterior regeneración de plántulas. Se ensayó una etapa de inducción en la que se probaron 12 tratamientos en medio MS+VitB5 suplementado con 2,4-D, KIN y BA adicionados solos o combinados y, otra, de expresión en MS, MS con Carbón activado (CA) o MS con reguladores de crecimiento (RC) en concentraciones reducidas a 1/10 parte de las adicionadas en la etapa inducción. Altos porcentajes, 70%, de regenerantes fueron obtenidos en el medio suplementado con 1 mgL-1 BA y transferidos a medio de expresión MS, así como en el medio con 1 mgL-1 BA + 3 mgL-1 2,4-D, y transferidos a medio de expresión con CA, 60%. El 70% de las plántulas regeneradas se desarrollaron exitosamente en invernadero. Este trabajo es el primero que aborda la expresión del potencial embriogénico de EZM de P. maliformis induciendo exitosamente respuestas embriogénicas no zigóticas a través de rutas directas e indirectas; los resultados obtenidos son aplicables al conocimiento de la embriogénesis no zigótica en otras pasifloras, con fines de mejoramiento y uso comercial.

The economic, ecological and medical significance of passion fruits has encouraged the development of multidisciplinary research in this group. In vitro culture, non-zygotic embryogenesis represents an alternative for plant regeneration; however, this technique has presented difficulties in the reproducibility of protocols as well as the development of certain embryos and abnormal plantlets in some species. We assessed in Passiflora maliformis L the morphogenic capacity in the mature zygotic embryos (MZE) to develop nonzygotic embryos (NZE), and subsequent plantlets regeneration. We tested an induction stage with 12 treatments in MS + VitB5 medium supplemented with 2,4-D, KIN and BA added alone or combined and, another with a MS, MS with Activated Charcoal (AC) or MS with growth regulators (GR) in 1/10 concentrations reduced to 1/10 of those added in the induction stage. We obtained high percentages, 70%, of regenerants in the medium supplemented with 1 mgL-1 BA and transferred to the MS expression medium, as well as in the medium with 1 mgL-1 BA + 3 mgL-1 2,4-D, and transferred to the expression medium with AC, 60%. 70% of the regenerated seedlings were successfully grown in the greenhouse. This is the first research that addresses the expression of the MZE embryogenic potential in P. maliformis, inducing a successfully embryogenic non-zygotic responses through direct and indirect routes; the obtained results are relevant to the knowledge of non-zygotic embryogenesis in other passion fruits, for breeding and commercial uses.

Vegetation dynamics between an open patch and a forest edge.

The study was conducted in two adjacent open area (patches and forest edges) resulted from a major blowdown as a laboratory exercises in SFI 223 (Advanced Silviculture). The two areas were utilized to understand the growth dynamics of the resulting vegetation in the plots. Findings of the study reveals that the forest edge and open patch still covered with various big indigenous and exotic tree species, and lianas. Open patch has more regenerants than forest edge. The comparatively higher difference of number of regenerants in open patch particularly might be due to the fact that Forest Edge have been fully covered with vines and other woody climbers that suppressed the growth of regenerants. For basal area, still open patch has higher B.A of 23.26cm2.Minimal growth was observed in the forest edge site for the 3 weeks measuring interval. This might caused to the relatively short interval of data collection aside from the dry season occurring on the month of data collection and other site factors such as sunlight competition from cover vegetations, nutrient competition from shrubs, lianas, and grasses. In the open patch, the highest growth increment of 21.473 cc is due to the significant growth increment and absolutely higher abundance of regenerants present and low mortality rate Another possible reason is that, the site is located at SE aspects were sun can constantly penetrate to the forest floor mat drives energy for the growth of the regenerates present.