SEM of seed coat criteria in relation to cytological variations elucidated by multivariate analyses in the genus Primula L. (Primulaceae).

Abstract

Seed macro-morphology and testa epidermal cell patterns were examined by scanning electron microscopy (SEM) for representatives of the Primula species particularly those with divisive chromosome counts in order to reassess their taxonomic delimitation. The characters used were that of the seed size (length/width ratio), testa (multicellular sculpture); cell (length/width ratio and homogeneity of size); anticlinal walls of epidermal cells (level, undulation, thickness and secondary sculpture); periclinal walls of epidermal cells (level and secondary sculpture). The specific relationships were established based on UPGMA-clustering and principal components analyses by using different modules of the NTSYS-pc 2.2 and the STATISTICA 5.5 programs. The produced data was compared with the cytological criteria of the studied species by measuring each of the phenograms distortion; from their relevant data matrices; and association to each other based on their cophenetic (ultrametric) correlation coefficients. Regression coefficients of each principal component on the corresponding character were used to analyze the contributing characters in the differentiation of the groups. Comparison of the SEM and cytological criteria revealed that, the two data sets were consistent with a percentage of 62% in differentiating the species studied. The present data were useful in confirming the close relationship between P. hirsuta and P. palinuri in spite of their variation in the diploid chromosome number; revealing the possibility of merging P. denticulata and P. rosea in the same section; supporting the deviation of P. loeseneri and P. frondosa that have previously been arisen based on the variability in basic chromosome numbers.