Proteomic and Physiological Indices-Based Selection of Broadly Diverse Sugarcane (Saccharum Spp) New Genotypes

Document Type : Original Article

Authors

1 Breeding and Genetics Department, Sugar Crops Research Institute, Agriculture Research Centre

2 Physiology and Chemistry Department, Sugar Crops Research Institute, Agriculture Research Centre

Abstract

Distantly-related 42 (S1-S42) genotypes of sugarcane (Saccharum spp) were selected phenotypically from  new genotypes generated from seeds of an open-pollinated parent, EH 26-2  (pedigree, LCP 81-10 X cp76-331) unfortunately, at the age of 100-days-old, two of the selected genotypes, namely S29 and S36, could not adapt to environmental conditions and were excluded from consideration. Proteomic analysis was carried out involving quantitative analysis of total soluble protein of leaf tissue extracts at five month-old plants and electrophoresis separation of proteins. The analysis showed significant differences among genotypes, in the total soluble protein content which ranged from 4.42 ± 0.22 to 2.73 ± 0.06 mg/g tissues, which were observed in genotype S37 and S28, respectively. Despite the results of total protein analysis of sugarcane leaf tissues appeared to vary among genotypes, it did not suggest evidence that protein content alone was a reliable marker for identifying genotypes. The analysis of protein by SDS-PAGE revealed clear differences in intensity and number of bands amongst genotypes. Furthermore, phylogenetic analysis of the 40 genotypes elucidated by electrophoresis, showed a wide range of total protein polymorphic variants. At least four (4) distinguishable clusters of genotypes were identified, amongst which was a cluster containing genotypes S17, S18, S25, S26 and S27; which were most distantly-related to the sub-cluster containing S35, S37, S42, S38, S39 and S40. Moreover, the physiological profiles of these genotypes were assessed at the age of 180 days, the leaf physiological characters of the remaining eleven potential sugarcane genotypes, relevant to plant response of drought, were evaluated. The studied parameters; included stomata length, width and number, epicuticular wax, relative leaf water content, chlorophyll content, peroxidase activity and proline content revealed that the distantly-related genotypes S25 and S40 which could be potential as future varieties in addition, the eleven genotypes may be useful parents in future sugarcane breeding programs in crosses to identify hybrids with high specific combining ability.

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