Cloning,characterization and overexpression of a 14‐3‐3 ω protein from oil palm (Elaeis guineensis)

Plant 14‐3‐3 proteins are involved in signal transduction pathways of nitrogen and carbohydrate metabolism. An Eg14‐3‐3 ω gene was isolated from the mesocarp of oil palm. The 1055‐bp cDNA had an open reading frame of 774 bp that encoded for 258 amino acids, and the cDNA had 113‐bp and 195‐bp 5′‐ and 3′‐untranslated regions, respectively. The calculated molecular weight was 28.06 kDa, with a pI of 5.04. The palm 14‐3‐3 showed closest identity to 14‐3‐3 proteins of the omega group. The entire sequence of Eg14‐3‐3 ω showed 83% identity with 14‐3‐3 protein isoform 16R from Solanum tuberosum. Phylogenetic analysis showed that the Eg14‐3‐3 isoform was within the omega (ω) subgroup and, thus, was designated Eg14‐3‐3 ω. The Eg14‐3‐3 ω expression patterns were strong in the mesocarp as compared to the root. When Eg14‐3‐3 ω cDNA was overexpressed in transgenic calli, there was higher accumulation of oil in the transgenic calli than in the controls. Therefore, Eg14‐3‐3 ω has potential for applications in the breeding of oil palms in the future.     

The role of synthetic pesticides in the intensification of highland agriculture in Thailand

The objective of this study is to quantify the relationship between synthetic pesticide use and agricultural intensification in the northern highlands of Thailand. We surveyed the crop management decisions of 295 farmers across 12 villages, and assessed the level of pesticide use in terms of monetary value, the active ingredients used, and using the Environmental Impact Quotient method. The results show that 77% of the farmers relied solely on synthetic pesticides for their pest management activities. The average farmer used 13.3 kg of active ingredients per hectare of agricultural land, but the variation was large. The highest levels of pesticide use were observed with the cultivation of cut flowers and greenhouse vegetables, while greater land use intensity was associated with increased usage of synthetic pesticides and a greater potential environmental impact. We found that those farmers following public certification of Good Agricultural Practices (Q-GAP), were neither able to reduce pesticide use nor its environmental impact. The findings suggest that to limit the environmental impact caused by the use of synthetic pesticides, greater priority must be given to developing and promoting non-synthetic methods of pest control together with gradually restricting the supply of highly hazardous pesticides.     

Symbiotic seed germination of Grammatophyllum speciosum Blume and Dendrobium draconis Rchb. f., native orchids of Thailand

In vitro symbiotic seed germination is an important tool not only for the study of orchid-fungus specificity but also for the production of mycobiont-infected healthy seedlings that could be valuable for both horticultural and conservation purposes. The current study compared effectiveness of eight putative orchid mycorrhizal fungi obtained from mature orchids in the genera Paphiopedilum, Cymbidium and Dendrobium, in promoting in vitro seed germination and protocorm development of Grammatophyllum speciosum Blume and Dendrobium draconis Rchb. f., native Thai orchids. The developmental stages of seeds and protocorms cultured on Murashige and Skoog (MS) medium, oat meal agar (OMA), or OMA inoculated with one of the eight fungal isolates were evaluated weekly. Two isolates of Epulorhiza repens (Bernard) Moore (=anamorphic species of Tulasnella calospora (Boud.) Juel), Da-KP-0-1 and Pv-PC-1-1, were found to be the most effective fungi in promoting protocorm development of G. speciosum. At week 13, protocorms co-cultured with either one of these two fungal isolates, on the average, were significantly more advanced than those sown on OMA. Protocorms co-cultured with isolate Pv-PC-1-1 were also significantly more advanced than those cultured on MS medium. For D. draconis seed germination, three fungal isolates of different anamorphic species of Tulasnella, C1-DT-TC-1, Pv-PC-1-1, and C3-DT-TC-2, were found to be the most effective fungi in promoting protocorm development. However, none of these fungal isolates outperformed MS medium. Additionally, the compatibility between the fungal isolates tested and the two orchid species was discussed.     

Effects of Photosynthetically Active Radiation and Air Temperature on CO2 Uptake of Pterocarpus macrocarpus in the Open Field

Since trees and plants can absorb CO2, forests are widely regarded as a carbon sink that may control the amount of CO2 in the atmosphere. The CO2 uptake rate of plants is affected by the plant species and environmental conditions such as photosynthetically active radiation (PAR), temperature, water and nutrient contents. PAR is the most immediate environmental control on photosynthesis while air temperature affects both photorespiration and dark respiration. In the natural condition, PAR and temperature play an important role in net CO2 uptake. The effects of PAR and air temperature on the CO2 uptake of Pterocarpus macrocarpus grown in a natural habitat were studied in the present work. Due to many uncontrollable factors, a simple rectangular hyperbola could not represent the measured data. The data were divided into groups of 2℃ intervals; CO2 uptake in each group may then be related to PAR by a rectangular hyperbola function. Using the obtained functions, the effect of PAR was removed from the original data. The PAR-independent CO2 uptake was then related to air temperature. Finally, the effects of PAR (I) and air temperature (Ta) on the CO2 uptake rate (A) were combined as:A= [(-0.0575 Ta2+ 2.6691 Ta-23.264)I/(-4.8794Ta2+227.13Ta-2456.9)+I](-0.00766Ta2+0.40666Ta-3.99924)