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[Dr. Wan-Hsing Cheng's] The Nucleolar protein SAHY1 is Involved in Pre-rRNA Processing and Normal Plant Growth

Hsu <em>et al</em>., 2020 Plant Physiology

Figure. Expression of SAHY1 in dividing endosperm cells
A, Subcellular localization of SAHY1. Endosperm cells in Arabidopsis may provide nutrients or signals for early embryo development. SAHY1 is a ribosome biogenesis factor, which expresses in the dividing endosperm cell layer at day 2 of hand-pollination. B, Dysfunction of SAHY1 causes delay of early embryo development (one-week-old embryos shown).

Plants cope with salt stress through the integration of multiple signal pathways. Although several key genes involved in salt stress response have been identified, numerous components remain unknown. To identify the novel components or the pathways they act on, we used genetic screening to identify several salt hypersensitive mutants (sahys). Of which, the sahy1 mutant shows slow growth, short root, pointed leaves, delay of early embryo development (Figure), and sterility. The SAHY1 is expressed in the tissues with active metabolism and cell division, and primarily restricted to the nucleolus and nucleus. The mutation of SAHY1 causes accumulation of pre-rRNA intermediates, changes the ribosome subunit profiling, and alters the expression of ribosome proteins and ribosome biogenesis factors. These data indicate that SAHY1 is involved in pre-rRNA processing and ribosome biogenesis, and paly an important role in normal plant growth and development. Our findings reveal that ribosome biogenesis is also associated with salt stress response. These findings are currently published in Plant Physiol (2020, https://academic.oup.com/plphys/advance-article/doi/10.1093/plphys/kiaa085/6054810). This work was done by three first coauthors (Pei-jung Hsua, Mei-Chen Tana, and Hwei-Ling Shen), together with other members in Dr. Wan-Hsing Cheng’s and Dr. Guang-Yuh Jauh’s labs.