Identification of ZHOUPI Orthologs in Rice Involved in Endosperm Development and Cuticle Formation

Abstract

The endosperm occupies most of the available space within mature rice seeds, contains abundant nutrients, and directly influences both the quality and quantity of rice production. Initial reports noted that AtZHOUPI (AtZOU) coordinates endosperm breakdown and the concomitant separation of the embryo from this structure in Arabidopsis. The results of this study show that rice genomes contain two most closely related homologs of AtZOU, OsZOU-1 and OsZOU-2; of these, OsZOU-1 expression is limited to within the endosperm where it can be detected throughout this structure 5 days after pollination (DAP). Its expression gradually decreases from seven DAP to nine DAP. The second of the two most closely related homologs, OsZOU-2, is highly expressed in leaves and stem, but is not detected in developing seeds. Heterologous expression of OsZOU-1 and OsZOU-2 in Atzou-4 mutants also revealed that OsZOU-1 partially complements the seed phenotypes of these individuals, while its counterpart, OsZOU-2, was unable to recover these phenotypes. The over-expression of OsZOU-1 severely disrupts both seed development and plant growth in transgenic rice lines, as plants in which this gene has been knocked down failed in the separation of endosperm from embryo and cuticle formation during seed development. The results of this study therefore suggest that OsZOU-1 is orthologous to the AtZOU, and regulates both endosperm development and cuticle formation in rice.

Plant proteases during developmental programmed cell death

“…Although the functional role of PASPA3 is still unknown, ALE1 is not involved in endosperm breakdown, but in the epidermal surface formation of the developing embryo (Yang et al, 2008). Recently, putative ZOU orthologs have been described in other species in association with endosperm development (Dou et al, 2018;Feng et al, 2018;Zhang et al, 2017b), but whether the role of ZOU in endosperm breakdown is conserved in all plant clades is unclear. During starchy endosperm PCD in cereal seeds, the pattern of cell death progression varies (Becraft and Gutierrez-Marcos, 2012).…”

Cytological, transcriptome and miRNome temporal landscapes decode enhancement of rice grain size

“…As regards to PCD (Fig. 1 I, and Additional file 1 : Figure S8B, C), four positive regulators, OsVPE1, OsVPE3 [ 45 ] , SDS2 [ 46 ], and OsZHOUP1 [ 47 ], and a negative regulator, OsSRT1 [ 48 ], exhibited differences in timing and levels of expression between SN and LGR. Hence, PCD was much more rapid in SN and may be an important contributor to GS.…”

OsLFR is essential for early endosperm and embryo development by interacting with SWI/SNF complex members in Oryza sativa

“…The endosperm supports the developing embryo as an altruistic tissue (Becraft and Gutierrez‐Marcos, 2012). Knockdown of the basic helix‐loop‐helix (bHLH) transcription factor OsZOU‐1 prevents the separation of the endosperm and embryo (Dou et al ., 2018). Moreover, the endosperm could affect embryo development in some other ways, not only through nourishment (Hong et al ., 1996).…”