Relationships Between the Development of Adventitious Roots and the Biosynthesis of Anthocyanins in First Internodes of Sorghum

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Abstract
The initiation and subsequent growth of adventitious roots in excised first internodes of Sorghum vulgare var. Wheatland milo were studied to determine the effect of these processes on anthocyanin biosyntheses. Segmentation of the internodes inhibited both adventitious root growth and accumulation of cyanidin equally in all segments; these results can be interpreted as a common requirement for bidirectional longitudinal transport. The presence of the coleoptile, especially in the absence of the base of the internode, inhibited the growth of the roots, but increased the number of root initials. High intensities of white and blue light which induced cyanidin synthesis slightly decreased adventitious root growth. Anaerobic conditions produced by solution infiltration strongly inhibited the growth of adventitious roots and greatly increased the accumulation of apigeninidin and luteolinidin. Addition of indoleacetic acid, kinetin and cofactors such as pyridoxine produced effects on the initiation and subsequent growth of these roots similar to those effects reported in the literature. But unlike root formation in hypocotyls, the initiation of adventitious roots in Sorghum internodes was not always directly correlated with the accumulation of anthocyanins, and the subsequent growth of these roots was frequently inversely correlated with some of the anthocyanin biosyntheses. The possible nature of these correlations is discussed. Comparisons are made with related Sorghum lines and mutants.