A practical workshop for generating simple DNA fingerprints of plants.

Gel electrophoresis DNA fingerprints offer a graphical and visually appealing illumination of the similarities and differences between DNA sequences of different species and individuals. A polymerase chain reaction (PCR) and restriction digest protocol was designed to give high-school students the opportunity to generate simple fingerprints of plants thereby illustrating concepts and techniques in genetics and molecular biology. Three combinations of primers/restriction enzyme targeting chloroplast DNA were sufficient to generate patterns that enabled visual discrimination of plant species. The protocol was tested with a range of common fruit, vegetable, and herb plants that could be easily cultivated and handled in the laboratory. Toxic or hazardous materials such as ethidium bromide and liquid nitrogen were avoided. The protocol was validated as a university outreach workshop targeted at a group of up to 10 high-school students. In a teaching laboratory, students sampled plants, setup the PCR reaction and restriction digest using microliter pipettes, and loaded the digested samples on an agarose gel. The workshop was structured as 2 × 2.5-hour sessions on separate days. The main challenges stemmed from the speed and accuracy of pipetting, especially at the gel loading stage. Feedback from students was largely positive, with the majority reporting that they had both enjoyed and learnt from the experience.

Fruit development, not GPP, drives seasonal variation in NPP in a tropical palm plantation.

We monitored seasonal variations in net primary production (NPP), estimated by allometric equations from organ dimensions, gross primary production (GPP), estimated by the eddy covariance method, autotrophic respiration (R(a)), estimated by a model, and fruit production in a coconut (Cocos nucifera L.) plantation located in the sub-tropical South Pacific archipelago of Vanuatu. Net primary production of the vegetative compartments of the trees accumulated steadily throughout the year. Fruits accounted for 46% of tree NPP and showed large seasonal variations. On an annual basis, the sum of estimated NPP (16.1 Mg C ha(-1) year(-1)) and R(a) (24.0 Mg C ha(-1) year(-1)) for the ecosystem (coconut trees and herbaceous understory) closely matched GPP (39.0 Mg C ha(-1) year(-1)), suggesting adequate cross-validation of annual C budget methods. However, seasonal variations in NPP + R(a) were smaller than the seasonal variations in GPP, and maximum tree NPP occurred 6 months after the midsummer peak in GPP and solar radiation. We propose that this discrepancy reflects seasonal variation in the allocation of dry mass to carbon reserves and new plant tissue, thus affecting the allometric relationships used for estimating NPP.