Agronomic Evaluation of Sugarcane Lines Transformed for Resistance to Sugarcane mosaic virus Strain E

Abstract

Genetic transformation of sugarcane (Saccharum spp.) holds promise for increasing yields and disease resistance. However, the tissue culture and transformation process may produce undesirable field characteristics in transgenic sugarcane. The primary objective of this study was to evaluate variability in agronomic characteristics and field disease resistance of sugarcane transformed for resistance to Sugarcane mosaic virus (SCMV) strain E. One hundred plants derived from cultivars CP 84‐1198 (n = 82) and CP 80‐1827 (n = 18), consisting of independent virus resistant lines VR 1 (n = 14), VR 4 (n = 24), VR 14 (n = 4), and VR 18 (n = 58) were evaluated in Exp. 1. Transgenics derived from CP 84‐1198 had significantly greater tonnes of sucrose per hectare (TSH) and significantly lower SCMV disease incidence than those from CP 80‐1827 in the plant‐cane (PC), first‐ratoon (1R), and second‐ratoon (2R) crops. Plants from the VR 18 line had significantly greater economic indices and lower SCMV disease incidence than the VR 4 line in all three crops. Phenotypic variation was high in Exp. 1, with tonnes of cane per hectare (TCH) ranging from 26 to 211 and TSH from 3.2 to 28.9 in the PC crop. Agronomic trait variation decreased with increased selection pressure in Exp. 2, evaluating 30 VR 18 lines, with TCH ranging from 70 to 149 and TSH from 8.5 to 19.0 in PC. The large variability in yield characteristics and disease resistance encountered in this study demonstrates the necessity of thorough field evaluation of transgenic sugarcane while selecting genetically stable and agronomically acceptable material for commercial use.