Agronomic evaluation of inbred lines derived from tissue cultures of maize

Abstract

Tissue culture-induced variation has been proposed as a novel source of variation for crop improvement. In maize (Zea mays L.), chromosome aberrations and qualitative genetic variants have been induced during in vitro culture. The proportion of regenerated plants carrying such variants has been shown to increase with culture age. The objective of this research was to evaluate the relationship between culture age and somaclonal variation for several agronomic traits. Six sib-pollinated ears of S0 (F2) plants in four OH43 ms/A188 populations each provided control seed and embryos for culture initiation. S2 lines derived from control seed and from plants regenerated 4 and 8 months after culture initiation were grouped according to their source ear and grown in 6 separate trials. A total of 305 tissue culture-derived and 48 control lines were evaluated as lines per se and in a testcross at each of three locations. Tissue culturederived lines and their testcrosses generally had lower grain yield and moisture. Since grain yield and moisture were not positively correlated in any trial, the highest yielding lines could be selected without increasing grain moisture. Grain yield and plant height tended to decrease with culture age. Although tissue culture-derived lines were, on average, inferior, the highest yielding line per se in three of six trials and the top-ranked line in five of six trials for yield and moisture were derived from tissue culture. The results indicate that tissue culture may generate variation for agronomic traits. Some of the variation, particularly the trend towards earlier maturity, could be useful. However, this method may require screening large populations because of the tendency to generate a large proportion of inferior lines.