start-ver=1.4 cd-journal=joma no-vol=137 cd-vols= no-issue=9 article-no= start-page=212 end-page= dt-received= dt-revised= dt-accepted= dt-pub-year=2024 dt-pub=20240831 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Mutations in starch BRANCHING ENZYME 2a suppress the traits caused by the loss of ISOAMYLASE1 in barley en-subtitle= kn-subtitle= en-abstract= kn-abstract=The genetic interactions among starch biosynthesis genes can be exploited to alter starch properties, but they remain poorly understood due to the various combinations of mutations to be tested. Here, we isolated two novel barley mutants defective in starch BRANCHING ENZYME 2a (hvbe2a-1 and hvbe2a-2) based on the starch granule (SG) morphology. Both hvbe2a mutants showed elongated SGs in the endosperm and increased resistant starch content. hvbe2a-1 had a base change in HvBE2a gene, substituting the amino acid essential for its enzyme activity, while hvbe2a-2 is completely missing HvBE2a due to a chromosomal deletion. Further genetic crosses with barley isoamylase1 mutants (hvisa1) revealed that both hvbe2a mutations could suppress defects in endosperm caused by hvisa1, such as reduction in starch, increase in phytoglycogen, and changes in the glucan chain length distribution. Remarkably, hvbe2a mutations also transformed the endosperm SG morphology from the compound SG caused by hvisa1 to bimodal simple SGs, resembling that of wild-type barley. The suppressive impact was in competition with floury endosperm 6 mutation (hvflo6), which could enhance the phenotype of hvisa1 in the endosperm. In contrast, the compound SG formation induced by the hvflo6 hvisa1 mutation in pollen was not suppressed by hvbe2a mutations. Our findings provide new insights into genetic interactions in the starch biosynthetic pathway, demonstrating how specific genetic alterations can influence starch properties and SG morphology, with potential applications in cereal breeding for desired starch properties. en-copyright= kn-copyright= en-aut-name=MatsushimaRyo en-aut-sei=Matsushima en-aut-mei=Ryo kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=HisanoHiroshi en-aut-sei=Hisano en-aut-mei=Hiroshi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=KimJune-Sik en-aut-sei=Kim en-aut-mei=June-Sik kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=McNellyRose en-aut-sei=McNelly en-aut-mei=Rose kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=4 ORCID= en-aut-name=OitomeNaoko F. en-aut-sei=Oitome en-aut-mei=Naoko F. kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=5 ORCID= en-aut-name=SeungDavid en-aut-sei=Seung en-aut-mei=David kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=6 ORCID= en-aut-name=FujitaNaoko en-aut-sei=Fujita en-aut-mei=Naoko kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=7 ORCID= en-aut-name=SatoKazuhiro en-aut-sei=Sato en-aut-mei=Kazuhiro kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=8 ORCID= affil-num=1 en-affil=Institute of Plant Science and Resources, Okayama University kn-affil= affil-num=2 en-affil=Institute of Plant Science and Resources, Okayama University kn-affil= affil-num=3 en-affil=Institute of Plant Science and Resources, Okayama University kn-affil= affil-num=4 en-affil=John Innes Centre, Norwich Research Park kn-affil= affil-num=5 en-affil=Department of Biological Production, Akita Prefectural University kn-affil= affil-num=6 en-affil=John Innes Centre, Norwich Research Park kn-affil= affil-num=7 en-affil=Department of Biological Production, Akita Prefectural University kn-affil= affil-num=8 en-affil=Institute of Plant Science and Resources, Okayama University kn-affil= END start-ver=1.4 cd-journal=joma no-vol=136 cd-vols= no-issue=4 article-no= start-page=94 end-page= dt-received= dt-revised= dt-accepted= dt-pub-year=2023 dt-pub=202304 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=FLOURY ENDOSPERM 6 mutations enhance the sugary phenotype caused by the loss of ISOAMYLASE1 in barley en-subtitle= kn-subtitle= en-abstract= kn-abstract=Starch is a biologically and commercially important glucose polymer synthesized by plants as semicrystalline starch granules (SGs). Because SG morphology affects starch properties, mutants with altered SG morphology may be useful in breeding crops with desirable starch properties, including potentially novel properties. In this study, we employed a simple screen for mutants with altered SG morphology in barley (Hordeum vulgare). We isolated mutants that formed compound SGs together with the normal simple SGs in the endosperm and found that they were allelic mutants of the starch biosynthesis genes ISOAMYLASE1 (HvISA1) and FLOURY ENDOSPERM 6 (HvFLO6), encoding starch debranching enzyme and CARBOHYDRATE-BINDING MODULE 48-containing protein, respectively. We generated the hvflo6 hvisa1 double mutant and showed that it had significantly reduced starch biosynthesis and developed shrunken grains. In contrast to starch, soluble α-glucan, phytoglycogen, and sugars accumulated to higher levels in the double mutant than in the single mutants. In addition, the double mutants showed defects in SG morphology in the endosperm and in the pollen. This novel genetic interaction suggests that hvflo6 acts as an enhancer of the sugary phenotype caused by hvisa1 mutation. en-copyright= kn-copyright= en-aut-name=MatsushimaRyo en-aut-sei=Matsushima en-aut-mei=Ryo kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=HisanoHiroshi en-aut-sei=Hisano en-aut-mei=Hiroshi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=GalisIvan en-aut-sei=Galis en-aut-mei=Ivan kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=MiuraSatoko en-aut-sei=Miura en-aut-mei=Satoko kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=4 ORCID= en-aut-name=CroftsNaoko en-aut-sei=Crofts en-aut-mei=Naoko kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=5 ORCID= en-aut-name=TakenakaYuto en-aut-sei=Takenaka en-aut-mei=Yuto kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=6 ORCID= en-aut-name=OitomeNaoko F. en-aut-sei=Oitome en-aut-mei=Naoko F. kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=7 ORCID= en-aut-name=IshimizuTakeshi en-aut-sei=Ishimizu en-aut-mei=Takeshi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=8 ORCID= en-aut-name=FujitaNaoko en-aut-sei=Fujita en-aut-mei=Naoko kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=9 ORCID= en-aut-name=SatoKazuhiro en-aut-sei=Sato en-aut-mei=Kazuhiro kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=10 ORCID= affil-num=1 en-affil=Institute of Plant Science and Resources, Okayama University kn-affil= affil-num=2 en-affil=Institute of Plant Science and Resources, Okayama University kn-affil= affil-num=3 en-affil=Institute of Plant Science and Resources, Okayama University kn-affil= affil-num=4 en-affil=Department of Biological Production, Akita Prefectural University kn-affil= affil-num=5 en-affil=Department of Biological Production, Akita Prefectural University kn-affil= affil-num=6 en-affil=College of Life Sciences, Ritsumeikan University kn-affil= affil-num=7 en-affil=Department of Biological Production, Akita Prefectural University kn-affil= affil-num=8 en-affil=College of Life Sciences, Ritsumeikan University kn-affil= affil-num=9 en-affil=Department of Biological Production, Akita Prefectural University kn-affil= affil-num=10 en-affil=Institute of Plant Science and Resources, Okayama University kn-affil= END start-ver=1.4 cd-journal=joma no-vol=9 cd-vols= no-issue= article-no= start-page=3745 end-page= dt-received= dt-revised= dt-accepted= dt-pub-year=2019 dt-pub=201936 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Imaging Amyloplasts in the Developing Endosperm of Barley and Rice en-subtitle= kn-subtitle= en-abstract= kn-abstract=Amyloplasts are plant-specific organelles responsible for starch biosynthesis and storage. Inside amyloplasts, starch forms insoluble particles, referred to as starch grains (SGs). SG morphology differs between species and SG morphology is particularly diverse in the endosperm of Poaceae plants, such as rice (Oryza sativa) and barley (Hordeum vulgare), which form compound SGs and simple SGs, respectively. SG morphology has been extensively imaged, but the comparative imaging of amyloplast morphology has been limited. In this study, SG-containing amyloplasts in the developing endosperm were visualized using stable transgenic barley and rice lines expressing amyloplast stroma-targeted green fluorescent protein fused to the transit peptide (TP) of granule-bound starch synthase I (TP-GFP). The TP-GFP barley and rice plants had elongated amyloplasts containing multiple SGs, with constrictions between the SGs. In barley, some amyloplasts were connected by narrow protrusions extending from their surfaces. Transgenic rice lines producing amyloplast membrane-localized SUBSTANDARD STARCH GRAIN6 (SSG6)-GFP were used to demonstrate that the developing amyloplasts contained multiple compound SGs. TP-GFP barley can be used to visualize the chloroplasts in leaves and other plastids in pollen and root in addition to the endosperm, therefore it provides as a useful tool to observe diverse plastids. en-copyright= kn-copyright= en-aut-name=MatsushimaRyo en-aut-sei=Matsushima en-aut-mei=Ryo kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=HisanoHiroshi en-aut-sei=Hisano en-aut-mei=Hiroshi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= affil-num=1 en-affil= Institute of Plant Science and Resources, Okayama University kn-affil= affil-num=2 en-affil= Institute of Plant Science and Resources, Okayama University kn-affil= END