A carbohydrate-binding protein, FLOURY ENDOSPERM 6 influences the initiation of A- and B-type starch granules in wheat.

Chia, T.; Chirico, M.; King, R.; Ramirez-Gonzalez, R.; Saccomanno, B.; Seung, D.; Simmonds, J.; Trick, M.; Uauy, C.; Verhoeven, T.; Trafford, K.

doi:10.1101/643759

bioRxiv · 10.1101/643759

A carbohydrate-binding protein, FLOURY ENDOSPERM 6 influences the initiation of A- and B-type starch granules in wheat.

Chia, T.·Chirico, M.·King, R.·Ramirez-Gonzalez, R.·Saccomanno, B.·Seung, D.·Simmonds, J.·Trick, M.·Uauy, C.·Verhoeven, T.·Trafford, K.

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Abstract

Previously, we identified a quantitative trait locus on the group 4 chromosomes of Aegilops and bread wheat that controls B-type starch-granule content. Here, we identify a candidate gene by fine-mapping in Aegilops and confirm its function using wheat TILLING mutants. This gene is orthologous to the FLOURY ENDOSPERM 6 (FLO6) gene of rice and barley and the PTST2 gene of Arabidopsis. In Triticeae endosperm, reduction in the gene dose of functional FLO6 alleles results in reduction, or loss, of B-granules. This is due to repression of granule initiation in late-grain development, but has no deleterious impact on the synthesis of A-granules. The complete absence of functional FLO6, however, results in reduced numbers of normal A-type and B-type granules and the production of highly-abnormal granules that vary in size and shape. This polymorphous starch seen in a wheat flo6 triple mutant is similar to that observed in the barley mutant Franubet. Analysis of Franubet (fractured Nubet) starch suggests that the mutant A-granules are not fractured but compound, due to stimulation of granule initiation in plastids during early-grain development. Thus, in different situations in Triticeae, FLO6 either stimulates or represses granule initiation.

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Chia, T., Chirico, M., King, R., Ramirez-Gonzalez, R., Saccomanno, B., Seung, D., Simmonds, J., Trick, M., Uauy, C., Verhoeven, T., Trafford, K.. 2019-05-23. A carbohydrate-binding protein, FLOURY ENDOSPERM 6 influences the initiation of A- and B-type starch granules in wheat.. https://doi.org/10.1101/643759

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