Inheritance of Chlorophyll Content in Leaves of Lettuce (Lactuca sativa)

Two lettuce (Lactuca sativa) varieties, 'Oakleaf (PI) and 'Baimach' (P-2) are not significantly different in SPAD values for chlorophyll content, while their green color appearance are different from each other. 'Oakleaf has common green leaves, while that of 'Baimach' is greyish green. In the segregating population from the cross 'Oakleaf' x 'Baimach', transgressive segregating plants in green intensity were observed, in both lighter green and darker green. Inheritance mode of green intensity was analysed using P-1, P-2, F-1, F-2, and F-3 populations induced from the cross 'Oakleaf x 'Baimach'. Green intensity of leaves was controlled by two major genes: 'Baimach' has aaBB, and 'Oakleaf has AAbb. The effects of gene A and B are almost the same, independent, additive and cumulative. Gene A and B showed a little heterosis effect, when the opposite is not in dominant homozygote state. The two genes, A and B, were designated Light green-2 and Light green-3, and symbolized Lg-2 and Lg-3, respectively.