The physiological and biochemical effects on Napier grass plants following Napier grass stunt phytoplasma infection

Napier grass stunt (NGS) phytoplasma, a phloem limited bacterium, infects Napier grass leading to severe yield losses in East Africa. The infected plants are strongly inhibited in growth and biomass production. In this study, phytoplasma-induced morphological changes of the vascular system and physiological changes were analysed and compared with uninfected plants. The study showed that the phytoplasmas are more abundant in source leaves and range from 103 bacteria/µg total DNA in infected roots to 106 in mature Napier grass leaves. Using microscopical, biochemical and physiological tools, we demonstrated that the ultrastructure of the phloem and sieve elements is severely altered in the infected plants, which results in the reduction of the both mass flow and the translocation of photoassimilates in the infected leaves. The reduced transport rate inhibits the photochemistry of photosystems II in the infected plants, which is accompanied by loss of chloroplastic pigments in response to the phytoplasma infection stress eventually resulting in yellowing of diseased plants. The phytoplasma infection stress also causes imbalances in the levels of defense-related antioxidants, glutathione and ascorbic acid, reactive oxygen species (ROS) and in particular hydrogen peroxide. This study shows that the infection of NGS phytoplasma in the phloem of Napier grass has an impact on the primary metabolism and activates a ROS dependent defense response.

EFECTO DE LA ZEOLITA NATURAL CLINOPTILITA SOBRE EL CRECIMIENTO DE DUNALIELLA SALINA (TEODORESCO, 1905) CULTIVADA EN UN FOTOBIORREACTOR DE MÚLTIPLES CÁMARAS OSCILANTES

We studied the growth and production of pigment of microalgae Dunaliella salina cultivated in<br />photobioreactor multicamera oscillating outside laboratory conditions to evaluate the effect of different<br />concentrations of zeolite (ZC). Growth was evaluated by cell count and pigment content was performed<br />by spectrophotometric techniques. The results indicate that the concentration of 50 mgL-1 of ZC produced<br />a better stimulus on the growth of the microalga reaching maximum cell density (MDC) of 5.51 ±0.45 x 106<br />celmL-1, growth rate (μ) 0.37 ±0.03 divday-1 and duplication time (Td) of 1.87 ±0.02 days. Likewise,<br />produced a greater increase in the total chlorophyll and carotenoids in the logarithmic phase of values<br />15.554 ±0.77 and 0.50 ±0.01 mgmL-1, respectively. Chloroplastic pigments concentration per volume of<br />culture has a significant correlation with maximum cell density of D. salina treatments based on zeolite at<br />all stages of growth with rMDC, chla.tot= 0.89 y una rMDC, carot.tot=0.926 at a level of significance (p &lt;0.01). The<br />results demonstrated the feasibility of using this product as a suitable substrate for the growth of the<br />microalga, being an innovative alternative and less costly to obtain significant metabolites.

Morphological and physiological photon flux influence under in vitro culture of apple shoots

The aim of the present study was to evaluate the growth and development of apple rootstock shoots submitted to different photon flux densities (7, 14, 21 and 60 µmol m-2 s-1) and three culture media. The best photon flux for maximizing growth, number of shoots and leaves was 14 µmol m-2 s-1, which also resulted in the highest values of chloroplastic pigments. On the other hand, the highest photon flux (60 µmol m-2 s-1) decreased significantly these parameters. Medium with reduced sucrose concentration did not affect the analyzed parameters, enabling an efficient multiplication of the cultivar with only 1% of sucrose.

Anomalous Transformation of Chloroplastic Pigments in Gordal Variety Olives during Processing for Table Olives

The results of a qualitative and quantitative study of pigments, carried out during the processing of Gordal variety olives for table use, has provided valuable information on the type, extent, and mechanism of degradation of the chlorophylls and carotenoids present in the fresh fruit. Unexpected results were obtained, since the initial treatment of the fruits with NaOH did not provoke chlorophyllase activity. However, the alkaline pH brought about the oxidation of chlorophylls, giving rise to Mg-phytyl-chlorin e6 and Mg-phytyl-rhodin g7. Subsequently, as a consequence of the acid pH generated in the fermentation medium, these compounds were transformed into the corresponding Mg-free derivatives, phytyl-ch1orin e6 and phytyl-rhodin g7. At the same time, those chlorophylls which initially escaped transformation were converted into their corresponding pheophytins. In addition, small amounts of pyropheophytin a, pheophorbides a and b, and pyropheophorbide a were detected, As far as the carotenoid fraction is concerned, β-carotene and lutein remained unaltered throughout processing, and only those components with molecular structures sensitive to the acid medium were affected. The total balance of pigment material indicated that there was a slow but progressive decrease in the concentration of the chlorophyllic and carotenoid fractions, which indicates that a certain amount of these pigments is degraded into colorless products.