Effects of OsCDPK1 on the Structure and Physicochemical Properties of Starch in Developing Rice Seeds

Abstract

Overexpression of a constitutively active truncated form of OsCDPK1 (OEtr) in rice produced smaller seeds, but a double-stranded RNA gene-silenced form of OsCDPK1 (Ri) yielded large seeds, suggesting that OsCDPK1 plays a functional role in rice seed development. In the study presented here, we propose a model in which OsCDPK1 plays key roles in negatively controlling the grain size, amylose content, and endosperm appearance, and also affects the physicochemical properties of the starch. The dehulled transgenic OEtr grains were smaller than the dehulled wild-type grains, and the OEtr endosperm was opaque and had a low amylose content and numerous small loosely packed polyhedral starch granules. However, the OEtr grain sizes and endosperm appearances were not affected by the temperature being either optimal (25 °C ) or low (22 °C) or high (31 °C) during the grain-filling phase. In contrast, the transgenic Ri grains were larger, had higher amylose contents, and had more transparent endosperms filled with tightly packed polyhedral starch granules. This demonstrates that OsCDPK1 plays a novel functional role in starch biosynthesis during seed development and affects the transparent appearance of the endosperm. These results improve our understanding of the molecular mechanisms through which the grain filling process occurs in rice.

Dynamic formation and transcriptional regulation mediated by phytohormones during chalkiness formation in rice

“…Several PKs are involved in phytohormonal signaling transduction. OsCDPK1 plays key roles in negatively controlling the grain size, amylose content, and endosperm appearance [ 37 ]. Meanwhile, OsCDPK1 inhibits the feedback of GAs biosynthesis through down-regulating GA3ox2 and GA20ox1 [ 91 ].…”

“…Transcription factors NF-YB1 [ 33 , 34 ], RSR1 [ 35 ] and OsbZIP58 [ 36 ] were reported to be involved in chalkiness formation. OsCDPK1 was reported to affect the physicochemical properties of starch and plays key roles in negatively controlling the grain size, amylose content, and endosperm appearance [ 37 ]. Chalk5 [ 10 ], PDIL1-1 [ 38 ], BiP1 [ 39 , 40 ], OsVPS9A [ 41 ], OsRAB5A [ 42 ] and GPA3 [ 43 ] involved in protein metabolism were reported to mediate chalkiness formation.…”

SUPER STARCHY1/ONAC025 participates in rice grain filling

“…In leaves, AGPases are known to be plastidial (Pérez et al, 2018). Furthermore, it has been shown that the grain size is altered when the starch structure changes (Matsushima et al, 2016; Wang, Zhang et al, 2018; Jiang et al, 2018). Hence, the expression of genes known to regulate seed size was examined in L_5 and L_6.…”

Basic Analysis of Calcium-dependent Protein Kinase Gene and Its Closely Related Gene Families in Solanum Pennellii Genome

“…Studies have shown that CDPK and CRK genes were involved in the regulation of root, stem, leaf development, owering, pollen germination, pollen tube growth and seed development 4,21,22,28,[43][44][45][46][47] , as well as in the regulation of gibberellin, auxin, salicylic acid, abscisic acid and methyl jasmonate biosynthesis 27,[48][49][50][51][52][53] . In addition, they also played a role in biological and abiotic stress responses [54][55][56][57][58][59][60][61][62][63][64] .…”