Predominantly symplastic phloem unloading of photosynthates maintains efficient starch accumulation in the cassava storage roots (Manihot esculenta Crantz)

Abstract Background Cassava ( Manihot esculenta Crantz) efficiently accumulates starch in its storage roots. However, how photosynthates are transported from the leaves to phloem (especially they unloaded into parenchymal cells of roots) remains unclear. Results Here, we investigated sucrose unloading pattern and impact on cassava root development using microstructural physiological analyses, namely, carboxyfluorescein (CF) C 14 isotope tracing. The expression profiling genes involved symplastic apoplastic transport was performed, which included enzyme activity, protein gel blot analysis, transcriptome sequencing analyses. These finding showed that carbohydrates mainly form sucrose, more than 54.6% present stem phloem. Sucrose predominantly symplastically roots; addition, there a shift accompanied by onset swelling. Statistical data microstructures indicated an enrichment plasmodesmata within sieve, companion, parenchyma developing roots cultivar but not wild ancestor. Tracing tests with CF verified existence channel, [ C] Suc demonstrated could rapidly diffuse cells. relatively high encoding synthase associated proteins appeared middle late stages primary fibrous roots, or secondary inverse transporters, cell wall acid invertase, soluble invertase these corresponding organs supported presence pathway. transcription profile their significantly positive correlation yield at population level confirmed is vitally important Conclusions In this study, revealed pattern. This essential for efficient accumulation high-yielding varieties compared low-yielding ancestors.