Characterization of selected species of the genus Onobrychis Mill. (Leguminosae) by using the seed coat patterns and cytological criteria.

Abstract

Seed macro-morphological characters were examined by scanning electron microscopy (SEM) for the two Egyptian and other four species of the pasture genus Onobrychis in order to support or oppose their taxonomic delimitation. The relationships of the examined species were constructed 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 figures were 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. Epidermal seed coat patterns of the present study were useful in characterization of the species studied of section Lophobrychis and were considerably consistence with the previous morphological, cytological and seed protein classifications. Comparison of the SEM and cytological criteria revealed that, the two data sets were consistent with a percentage of 70% in differentiating the species studied. The most contributing characters were the cell length/width ratio; level, undulation, thickness, secondary sculpture of anticlinal walls and level of outer periclinal walls. The two Egyptian species were similar in having irregular seed epidermal cell sizes and ribbed-reticulate pattern of the outer periclinal walls microrelief, whereas they differ in the seed shape; multicellular sculpture; anticlinal walls and the hilum micropylar region features. The present data helped in confirmation of the relationships between the studied species as established in their current taxonomic treatments.