| Phenotype Detail | The MtSucS1-antisense plants displayed an up to 90% reduction of MtSucS1 proteins in roots and nodules. Phenotypic studies of two independent MtSucS1-reduced lines demonstrated that only under conditions depending on nodulation, these plants appeared to be impaired in above-ground growth. Specifically plant height, shoot weight, leaf development, flowering as well as seed maturation were reduced, and the efficiency of photosynthesis was affected. Concomitantly, a significantly enhanced root to shoot ratio with a marked increase in root tip numbers was observed. Root nodule formation was found retarded and the impaired nodulation was accompanied by a less efficient N acquisition. The decreased total N content of MtSucS1-antisense lines and an enhanced C to N ratio in roots, nodules, and shoots correlated with the extent of MtSucS1 knock-down. On the level of transcription, effects of an MtSucS1-reduction were evident for genes representing important nodes of the nodule C and N metabolism, while metabolite profiling revealed significantly lower levels of amino acids and their derivatives particularly in strongly MtSucS1-reduced nodules. |
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