Changes in chlorophyll, polyamines and chloroplast ultrastructure of Puccinia striiformis induced ‘green islands’ on detached leaves of Triticum aestivum

Biochemical and ultrastructure features of ‘green islands’ were investigated using detached wheat leaves infected with the yellow rust Puccinia striiformis. Chlorophylls appear to culminate 10 d after inoculation at which point ‘green islands’ were fully developed. These changes were paralleled by an increase in spermidine and spermine content which play an important role in formation of ‘green islands’. Retention of chlorophyll was demonstrated in leaf tissues of wheat plants supplied with exogenous putrescine, spermidine and spermine. Putrescine was least and spermidine and spermine most effective in retarding loss of chlorophylls. Ultrastructural observation revealed that chloroplasts were regenerated in ‘green islands’ where many proplastids were detected. The regeneration of chloroplasts coincided with the high concentration of chlorophylls and polyamines particularly spermidine and spermine. The ultrastructural changes of chloroplasts in leaf cell containing infection structures were parallel to physiological changes.