AUTHOR=Yu Li , Zhang Shuojun , Liu Hailun , Wang Yufei , Wei Yiting , Ren Xujiao , Zhang Qian , Rong Junkang , Sun Chendong 

TITLE=Genome-Wide Analysis of SRNF Genes in Gossypium hirsutum Reveals the Role of GhSRNF18 in Primary Root Growth

JOURNAL=Frontiers in Plant Science

VOLUME=12

YEAR=2021

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2021.731834

DOI=10.3389/fpls.2021.731834

ISSN=1664-462X

ABSTRACT=<p>Root systems are instrumental for water and nutrient uptake and the anchorage of plants in the soil. Root regulating GL2-interacting repressors (GIRs) contain a Short RING-like Zinc-Finger (SRNF) domain, but there has been no comprehensive characterization about this gene family in any plant species. Here, we renamed the GIR-like proteins as SRNF proteins due to their conserved domain and identified 140 <italic>SRNF</italic> genes from 16 plant species including 24 <italic>GhSRNF</italic> genes in <italic>Gossypium hirsutum</italic>. Phylogenetic analysis of the SRNFs revealed both similarities and divergences between five subfamilies. Notably, synteny analysis revealed that polyploidization and whole-genome duplication contribute to the expansion of the <italic>GhSRNF</italic> gene family. Various cis-acting regulatory elements were shown to be pertinent to light, phytohormone, defense responsive, and meristem regulation. Furthermore, <italic>GhSRNF2</italic>/<italic>15</italic> were predominantly expressed in root, whereas the expression of <italic>GhSRNF18</italic> is positively correlated with the primary root (PR) length in <italic>G. hirsutum</italic>, quantified by quantitative real-time PCR (qRT-PCR). Over-expression of <italic>GhSRNF18</italic> in <italic>Arabidopsis</italic> and virus-induced gene silencing (VIGS) of <italic>GhSRNF18</italic> in <italic>G. hirsutum</italic> has revealed the role of GhSRNF18 in PR growth. The over-expression of <italic>GhSRNF18</italic> in <italic>Arabidopsis</italic> resulted in an increase of meristematic activities and auxin accumulations in PRs, which were consistent with the transcriptomic data. Our results suggested that <italic>GhSRNF18</italic> positively regulates PR growth. This study increased our understanding of the <italic>SRNF</italic> gene family in plants and provided a novel rationale for the further investigation of cotton root morphogenesis regulated by the <italic>GhSRNFs</italic>.</p>