Protein profiling in selected root crops

Several critical problems have hampered the development and growth of the root crop industry in the country. These include high perishability of cassava; acridity in taro; and pest and diseases of sweet potato (leathery mottles and scabs), cassava (spider mites and scale incests), yam (anthracnose), and taro (leaf blight). Although significant progress and promising results have been obtained for the use of chemicals, botanicals, cultural management practices, IPM and storage conditions, most of these problems still exists. However, protein expression profiling offers an answer to these problems. It provides an overall pattern of gene activity that serves as biochemical markers. These markers could provide insights on how the tissue behaves for abnormalities and what goes wrong when disease develops. Such protein markers are useful for diagnostic purposes and varietal improvement. Tulin and Ecleo (PhilRootCrops) established a protein expression profile of cassava, taro, sweet potato, and yam. Findings of the study revealed the following: Protein expression profiles were established for acridity and blight infection in taro corms; storage condition and insect infestation in cassava roots; anthocyanin content and anthracnose infection in yam; and disease infection in sweet potato. From the profiles established, eight novel protein markers or biochemical markers were identified corresponding to six traits or conditions as follows: a) taro acridity- 55 kDa; b) blight infection in taro- 45 kDa; c) scale insect infestation in cassava stems- 40 kDa and 28 kDa; d) spider mite infestation in cassava leaves- 70 kDa and 30 kDa; e) anthracnose infection in yam leaves- 22 kDa; and f) storage condition of cassava roots-35 kDa. No markers were reported for sweet potato. The 55 kDa acridity-specific protein will be useful for screening and selecting non-acrid varieties in taro. This will aid breeding works for non-acrid varieties in taro. The 22 kDa anthracnose-specific protein could be used for detection of anthracnose-infected varieties, which is applicable in producing disease-free planting materials. Results of the study provided a good benchmark in determining the protein profiles of each of the root crop species. Further identification, isolation, and cloning of the identified biochemical markers need to be pursued to provide a more detailed characterization and functional analysis of the specific genes involved for the expression of the corresponding traits.