We show that the Pvlea-18 gene encodes a 14-kD protein that accumulates during late embryogenesis. Related proteins have been detected in both monocots and dicots, indicating that PvLEA-18 is a member of a new family of LEA (Late Embryogenesis Abundant) proteins. We also show that the PvLEA-18 transcript and protein accumulate not only in different organs of the bean seedlings during water stress but also in well-irrigated seedlings. This accumulation occurs in seedling regions with more negative values of water and osmotic potentials, such as the growing region of the hypocotyl. This phenomenon has not previously been described for LEA proteins. Immunohistochemical localization showed that the PvLEA-18 protein is present in the nucleus and cytoplasm of all cell types, with a higher accumulation in the epidermis and vascular cylinder tissues, particularly in protoxylem cells and root meristematic tissues. We found a similar localization but a higher abundance in water-stressed seedlings.

No abstract

Water availability is one of the main limitations of potato yields due to the high sensitivity of this crop to water deficit. The objective of this study was to determine the effect of water deficit on some physiological and biochemical responses in yellow diploid potato plants (Solanum tuberosum L. Group Phureja) of the cultivars Criolla Colombia, Criolla Dorada and Criolla Ocarina. Plants at tuber initiation were subjected to two treatments: continuous irrigation and water deficit imposed by withholding water at tuber initiation for 17 d. The results showed that plants under water deficit increased chlorophyll concentration, malondialdehyde and proline content. However, these plants showed a decrease in stomatal conductance, leafarea, total dry mass and exhibited a higher root/shoot ratio in all potato cultivars. In addition, all the cultivars also showed a decrease in yield, which was associated with sensitivity to water stress. Although the high content of proline and high root/shoot ratio may be associated with tolerance to water deficit, this association was not observed in these cultivars, probably due to the high reduction of stomatal conductance, which limited the production of photoassimilates, plant growth, and,therefore, the yield.

Crecimiento de Jatropha curcas L. fertilizada con nitrógeno y potasio en condiciones de bosque seco tropical de Colombia , with no differences presented among the treatments with fertilizer application. The highest absolute growth rate (AGR) was observed when 150 kg ha -1 of N+180 kg ha -1 of K 2 O were applied at the start of the reproductive phase (345 das), 24.5 g d -1. The specific leaf area (SLA) did not present a response to the treatments. The relative growth rate (RGR) reached zero value at 402 das for the plants without fertilizers. The accumulation of biomass in J. curcas was influenced by the fertilizers with N and K, presenting rapid initial vegetative growth (first 165 das) which decreased with the starting of the reproductive phase.Frente a la demanda de los biocombustibles, las especies vegetales no comestibles que no compitan con los cultivos tradicionales en Colombia, aparecen como una alternativa importante, tal como Jatropha curcas L. Con el fin de generar mayor conocimiento sobre el crecimiento de esta especie se aplicaron diferentes dosis de fertilizantes con N y K durante los primeros 435 días después de la siembra (dds) en zona de bosque seco tropical. Con la mayor dosis de N (150 kg ha . El área foliar específica AFE no presentó respuesta a los tratamientos, la tasa relativa de crecimiento (TRC) llegó a un valor de 0 a los 402 dds para las plantas sin fertilizar. La acumulación de biomasa en J. curcas estuvo influenciada por la fertilización con N y K, presentando un rápido crecimiento vegetativo inicial (primeros 165 dds), el cual se disminuyó al pasar a la etapa reproductiva.