Increase in Phloem Area in the Tomato hawaiian skirt Mutant Is Associated with Enhanced Sugar Transport

[EN] The HAWAIIAN SKIRT (HWS) gene has been described in Arabidopsis, rice, tomato and poplar where it seems to perform distinct functions with relatively little overlap. In tomato, alteration of the gene function confers facultative parthenocarpy, thought to be a consequence of changes in the microRNA metabolism. In the rice mutant, improvement in panicle architecture is associated with an increase in grain yield. Knowing that hws tomato fruits show a higher Brix level, it was suspected that vascular bundles might also be altered in this species, in a similar fashion to the rice phenotype. The pedicel structure of the hws-1 line was therefore examined under the microscope and sugar concentrations from phloem exudate were determined in an enzymatic assay. A distinct increase in the phloem area was observed as well as a higher sugar content in mutant phloem exudates, which is hypothesized to contribute to the high Brix level in the mutant fruits. Furthermore, the described phenotype in this study bridges the gap between Arabidopsis and rice phenotypes, suggesting that the modulation of the microRNA metabolism by HWS influences traits of agricultural interest across several species. This work was supported by JSPS KAKENHI Grant No. 25252008 and Grant No. 17H01461 to H.E., and Science and Technology Research Promotion Program for Agriculture, Forestry, Fisheries and Food Industry, Japan (Grant No. 26013A) to H.E. P.G. is grateful to the Japanese Society for the Promotion of Science for the JSPS postdoctoral grant FY2019-P19105. Fabien Lombardo; Gramazio, P.; Hiroshi Ezura (2021). Increase in Phloem Area in the Tomato hawaiian skirt Mutant Is Associated with Enhanced Sugar Transport. Genes. 12(6):1-11. https://doi.org/10.3390/genes12060932