Crucial Role of SCC3 in Maintaining Sister Chromatid Cohesion and Enabling Homologous Pairing During Rice Meiosis

Core Concepts

SCC3, a conserved cohesin subunit, is essential for maintaining sister chromatid cohesion during both mitosis and meiosis, and acts as an axial element crucial for homologous chromosome pairing and synapsis in rice meiosis.

Abstract

The study investigates the functional roles of SCC3, a conserved cohesin subunit, in rice mitosis and meiosis. In mitosis: SCC3 is required for maintaining sister chromatid cohesion. Mutations in SCC3 lead to premature separation of sister chromatids during prometaphase and metaphase. SCC3 is localized on chromatin from interphase to prometaphase, and its dissociation from chromosomes coincides with the metaphase-to-anaphase transition. In meiosis: SCC3 acts as an axial element, colocalizing with the meiosis-specific cohesin subunit REC8 from leptotene to diplotene. SCC3 is essential for homologous chromosome pairing and synapsis. Mutations in SCC3 result in severe defects in these processes. The loading of SCC3 onto meiotic chromosomes depends on REC8, indicating a hierarchical relationship between these cohesin subunits. In the absence of SCC3, meiotic DNA double-strand breaks are preferentially repaired using sister chromatids as templates, rather than homologous recombination. The study reveals the multifaceted roles of SCC3 in regulating chromosome dynamics and meiotic progression, highlighting its importance as a conserved cohesin subunit.

Stats

SCC3 is a highly conserved protein containing a STAG domain. The scc3 weak mutant exhibits decreased plant height, tiller number and panicle length. In scc3, around 70.6% of root tip cells showed partially or completely separated sister chromatids. The distance between sister centromeres increased significantly in scc3 somatic cells. The number of DMC1, RAD51 and ZIP4 foci were significantly decreased in scc3 meiocytes compared to wild type.

Quotes

"SCC3 emerges as an axial element intricately involved in homologous pairing, synapsis, recombination progress, and crossover (CO) formation." "Our findings also shed light on the regulation of SCC3 localization by REC8." "We propose that SCC3 acts as a constituent of the cohesin complex, which plays an indispensable role in meiotic homologous pairing and synapsis."

Key Insights Distilled From

SCC3 is an axial element essential for homologous chromosome pairing and synapsis

by Zhao,Y., Ren... at www.biorxiv.org 11-23-2023

https://www.biorxiv.org/content/10.1101/2023.11.22.568373v2

Deeper Inquiries

How might the insights from this study on the roles of SCC3 in meiosis be leveraged to improve crop breeding strategies?

The study on the roles of SCC3 in meiosis provides valuable insights that can be leveraged to enhance crop breeding strategies. Understanding the function of SCC3 in meiosis, particularly its involvement in homologous pairing, synapsis, recombination progress, and crossover formation, can aid in the development of breeding techniques aimed at improving genetic diversity and creating novel crop varieties. By manipulating the expression or activity of SCC3, breeders may be able to enhance recombination efficiency, leading to the generation of crops with desirable traits. Additionally, the knowledge gained from this study can be used to develop molecular markers for selecting plants with improved meiotic stability and fertility, which are crucial factors in crop breeding programs.

What other cohesin subunits or associated proteins could potentially interact with SCC3 to modulate its functions in mitosis and meiosis?

In addition to SCC1, which has been identified as an interacting partner of SCC3 in this study, other cohesin subunits and associated proteins could potentially interact with SCC3 to modulate its functions in mitosis and meiosis. One such protein is REC8, a meiosis-specific cohesin component that plays a crucial role in establishing sister chromatid cohesion during meiosis. REC8 is known to interact with other cohesin subunits and is essential for proper chromosome segregation during meiosis. Additionally, proteins involved in DNA repair, recombination, and chromatin remodeling, such as RAD21, SMC1, and SMC3, may also interact with SCC3 to regulate its functions in maintaining chromosome structure and stability. Further studies are needed to elucidate the specific protein-protein interactions that modulate SCC3's roles in mitosis and meiosis.

Given the importance of sister chromatid cohesion in genome stability, how could the understanding of SCC3's role be extended to investigate its potential involvement in plant development and stress responses?

The understanding of SCC3's role in sister chromatid cohesion and chromosome dynamics can be extended to investigate its potential involvement in plant development and stress responses. As SCC3 is essential for maintaining genome stability during cell division, its dysregulation could lead to chromosomal abnormalities, affecting plant growth and development. By studying the impact of SCC3 on meiosis and mitosis, researchers can gain insights into how disruptions in sister chromatid cohesion may influence plant development processes, such as seed formation, germination, and growth. Furthermore, as stress responses often involve DNA damage repair mechanisms, SCC3's role in meiotic DSB repair using sister chromatids as templates could be crucial for plant survival under stress conditions. Investigating how SCC3 interacts with other proteins involved in stress responses, such as DNA repair enzymes and signaling molecules, could provide valuable information on the molecular mechanisms underlying plant stress tolerance. By elucidating the role of SCC3 in plant development and stress responses, researchers can potentially identify new targets for improving crop resilience and productivity in challenging environments.