The Use of Proteomic Tools to Address Challenges Faced in Clonal Propagation of Tropical Crops through Somatic Embryogenesis.

In many tropical countries with agriculture as the mainstay of the economy, tropical crops are commonly cultivated at the plantation scale. The successful establishment of crop plantations depends on the availability of a large quantity of elite seedling plants. Many plantation companies establish plant tissue culture laboratories to supply planting materials for their plantations and one of the most common applications of plant tissue culture is the mass propagation of true-to-type elite seedlings. However, problems encountered in tissue culture technology prevent its applications being widely adopted. Proteomics can be a powerful tool for use in the analysis of cultures, and to understand the biological processes that takes place at the cellular and molecular levels in order to address these problems. This mini review presents the tissue culture technologies commonly used in the propagation of tropical crops. It provides an outline of some the genes and proteins isolated that are associated with somatic embryogenesis and the use of proteomic technology in analysing tissue culture samples and processes in tropical crops.

Proteomic profiling of mature leaves from oil palm (Elaeis guineensis Jacq.).

Oil palm is one of the most productive oil bearing crops grown in Southeast Asia. Due to the dwindling availability of agricultural land and increasing demand for high yielding oil palm seedlings, clonal propagation is vital to the oil palm industry. Most commonly, leaf explants are used for in vitro micropropagation of oil palm and to optimize this process it is important to unravel the physiological and molecular mechanisms underlying somatic embryo production from leaves. In this study, a proteomic approach was used to determine protein abundance of mature oil palm leaves. To do this, leaf proteins were extracted using TCA/acetone precipitation protocol and separated by 2DE. A total of 191 protein spots were observed on the 2D gels and 67 of the most abundant protein spots that were consistently observed were selected for further analysis with 35 successfully identified using MALDI TOF/TOF MS. The majority of proteins were classified as being involved in photosynthesis, metabolism, cellular biogenesis, stress response, and transport. This study provides the first proteomic assessment of oil palm leaves in this important oil crop and demonstrates the successful identification of selected proteins spots using the Malaysian Palm Oil Board (MPOB) Elaeis guineensis EST and NCBI-protein databases. The MS data have been deposited in the ProteomeXchange Consortium database with the data set identifier PXD001307.

Differential proteomic analysis of embryogenic lines in oil palm (Elaeis guineensis Jacq).

UNLABELLED: Oil palm tissue culture is one way to produce superior oil palm planting materials. However, the low rate of embryogenesis is a major hindrance for the adoption of this technology in oil palm tissue culture laboratories. In this study, we use proteomic technologies to compare differential protein profiles in leaves from palms of high and low proliferation rates in tissue culture in order to understand the underlying biological mechanism for the low level of embryogenesis. Two protein extraction methods, namely trichloroacetic acid/acetone precipitation and polyethylene glycol fractionation were used to produce total proteins and fractionated protein extracts respectively, with the aim of improving the resolution of protein species using two-dimensional gel electrophoresis. A total of 40 distinct differential abundant protein spots were selected from leaf samples collected from palms with proven high and low proliferation rates. The variant proteins were subsequently identified using mass spectrometric analysis. Twelve prominent protein spots were then characterised using real-time polymerase chain reaction to compare the mRNA expression and protein abundant profiles. Three proteins, namely triosephosphate isomerase, l-ascorbate peroxidase, and superoxide dismutase were identified to be potential biomarker candidates at both the protein abundant and mRNA expression levels. BIOLOGICAL SIGNIFICANCE: In this study, proteomic analysis was used to identify abundant proteins from total protein extracts. PEG fractionation was used to reveal lower abundant proteins from both high and low proliferation embryogenic lines of oil palm samples in tissue culture. A total of 40 protein spots were found to be significant in abundance and the mRNA levels of 12 of these were assessed using real time PCR. Three proteins namely, triosephosphate isomerase, l-ascorbate peroxidase and superoxide dismutase were found to be concordant in their mRNA expression and protein abundance. Triosephosphate isomerase is a key enzyme in glycolysis. Both l-ascorbate peroxidase and superoxide dismutase play a role in anti-oxidative scavenging defense systems. These proteins have potential for use as biomarkers to screen for high and low embryogenic oil palm samples.