Inheritance of Tuber Greening Under Light Exposure in Diploid Potatoes

American Journal of Potato Research,  May/Jun 2006  by Jakuczun, Henryka,  Zimnoch-Guzowska, Ewa

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Storage treatments influenced depth of tuber greening more than external greening (Table 7). Significant differences in external tuber greening under A and C treatments were found in only one family (ESG ? EWG). Depth of greening was significantly less in treatment C than in treatment A. Buck and Akeley (1967) found that intensity of tuber greening in six varieties was stronger after storage at 4.4 C than at 12.8 C or at 21.1 C, but greening was stronger after 2 months of storage than after 4 months. Griffiths et al. (1998) found that chlorophyll accumulation was little affected by storage temperature, but was slightly, although significantly, higher in tubers stored for 6 weeks in comparison to those stored for 14 weeks.

The correlations between external and depth of tuber greening we observed in this study indicate that these two types of tuber greening may be partially independently inherited (Table 8). Reeves (1988) also suggested that the three types of tuber greening he investigated might also be inherited independently.

Maternal Effect

There was little evidence that maternal effects were important for either external or depth of tuber greening. In only one storage regime for one set of reciprocal crosses was the effect significant. This is in agreement with the results of Parfitt and Peloquin (1981) who found no evidence for cytoplasmic inheritance of tuber greening.

General and Specific Combining Ability

Both GCA and SCA effects were important in tuber greening in diploid potatoes (Table 9). The male parents used in this study affected both external and depth of tuber greening much more than the female parents (Tables 10 and 11). They represented a wider range of variability of tuber greening from weak to strong, while there was little variation in the female parents. GCA was significant for the males in all storage environments for both external and depth of tuber greening, but significant for the females in only three cases over years. Significant GCA x year interactions of females for external and depth of greening in all treatments can suggest that they were probably much more influenced by environments than males (Table 9).

Few genetic studies on tuber greening have been reported and those were from many years ago. Akeley et al. (1962) concluded that in tetraploid potatoes tuber greening was inherited in a quantitative manner and that dominance was incomplete. They stated that genotypes with a weak tendency to tuber greening could be effectively selected. Parfitt and Peloquin (1981) found that inheritance of tuber greening in diploid potatoes was due to additive and epistatic effects. They estimated narrow sense heritability as 0.27 and broad sense heritability as 0.66, which indicated that the trait could be effectively selected in breeding programs.

Our studies found that both external and depth of tuber greening are inherited. The occurrences of no greened genotypes will allow the chance to transfer this trait into tetraploid level. We intend to transfer a low tendency of tuber greening into tetraploid breeding material via 4x-2x crosses.