INHERITANCE OF LEAF SPININESS AND SEGREGATION OF LEAF COLOR IN PINEAPPLE (ANANAS-COMOSUS L MERRILL)

Progenies from 13 artificial and six open-pollinated intervarietal pin eapple crosses were analyzed for leaf spininess and leaf color. A new hypothesis for the inheritance of the leaf spininess trait based on th e observed segregations is put foward. It dearly explains the segregat ion of 11 out of the 13 artificial crosses, whereas the current accept ed hypothesis (Collins and Kernes, J. Heredity 37: 123-128, 1946) expl ains only eight of the 13 crosses. Three crosses were crucial for the acceptance or rejection of both hypotheses. The crosses Boituva x Smoo th Cayenne and Perola x Smooth Cayenne, which involve ''non-piping'' a nd heterozygous for the S locus (Ss) parents, gave rise to spineless i ndividuals in the offspring, at the expected frequency of three spiny to one spineless. This fact cannot be explained by Collins and Kernes' (1946) hypothesis. The cross Roxo-de-Tefe x Rondon resulted in nearly 100% spiny descendants, different from the frequency expected by the Collins and Kernes' hypothesis (50% spiny: 50% spineless). The new hyp othesis allows the identification of two new clones as ''piping'' type s (Manauara Inerme and Pina Negra) and confirms that the genotypic con stitution of the Rondon clone is probably ppss (spineless ''non-piping ''). When the genotype is pp, the S locus produces the completely spin y phenotypes (ppSS and ppSs), which are dominant over the spineless on e (ppss). The partial leaf spininess of the cultivar Smooth Cayenne, d escribed as heterozygous for the S locus (ppSs), must be caused by gen otype x environment interactions, genetic background effects, modifyin g genes and/or other unknown facts. Green leaf color has incomplete do minance over purple leaf color, but green predominates.