Comprehensive analysis of SAUR gene family in citrus and its transcriptional correlation with fruitlet drop from abscission zone A

Abstract

Small auxin-up RNA (SAUR) gene family is large, and the members of which can be rapidly induced by auxin and encode highly unstable mRNAs. SAUR genes are involved in various developmental and physiological processes, such as leaf senescence, fruitlet abscission, and hypocotyl development. However, their modes of action in citrus remain unknown. Hereby, a systematic analysis of SAUR gene family in citrus was conducted through a genome-wide search. In this study, a total of 70 SAUR genes, referred to as CitSAURs, have been identified in citrus. The evolutionary relationship and the intro-exon organization were analyzed, revealing strong gene conservation and the expansion of particular functional genes during plant evolution. Expression analysis showed that the major of CitSAUR genes were expressed in at least one tissue and showed distinctive expression levels, indicating the SAUR gene family play important roles in the development and growth of citrus organs. However, there were more than 20 CitSAUR genes such as CitSARU36, CitSAUR37, and CitSAUR54 exhibiting very low expression level in all tissue tested. Twenty-three out of 70 CitSAUR genes were responded to indole-3-acetic acid (IAA) treatment, of which just CitSAUR19 was down-regulated. Additionally, 14 CitSAUR genes exhibited distinct changes during fruitlet abscission, however just 5 of them including CitSAUR06, CitSAUR08, CitSAUR44, CitSAUR61, and CitSAUR64 were associated with fruitlet abscission. The current study provides basic information for the citrus SAUR gene family and will pave the way for deciphering the precise role of SAURs in citrus development and growth as well as fruitlet abscission.

A genome-wide analysis of the small auxin-up RNA (SAUR) gene family in cotton

“…Only one SAUR gene in Arabidopsis has an intron, while none of the OsSAURs in rice harbors any intron. Among other species, 6 out of 58 SAUR genes in maize, 3 out of 99 SAUR genes in tomato, 9 out of SAUR genes in potato, 10 out of 70 SAUR genes in citrus contained introns based on the sequenced genomes [ 3 , 6 , 8 – 10 ]. Similar phenomenon in cotton was found in this study in that about 9.3% of the SAUR genes in cotton carried introns.…”

“…Since the first SAUR gene was identified in elongating soybean hypocotyl sections [ 5 ], members of this gene family have been identified by genome-wide analyses in diverse plant species, such as Arabidopsis [ 3 ], rice [ 6 ], sorghum [ 7 ], tomato [ 8 ], potato [ 8 ], maize [ 9 ], citrus [ 10 ], and ramie [ 11 ]. In total, more than 674 SAUR genes were identified from different species, but only a small portion of them have been functionally characterized.…”

Transcriptional and Hormonal Regulation of Weeping Trait in Salix matsudana

“…SAUR family genes ( SAUR22, 23 and 32 ) were up-regulated in weeping willow. Chen et al revealed that SAUR19-24 function as positive effectors of cell expansion [ 35 ], and Xie et al demonstrated that SAUR32 induces short, hookless hypocotyls when overexpressed in Arabidopsis [ 36 ]. In addition, most GH3 family genes were up-regulated in weeping willow.…”

Genome-wide analysis and expression characteristics of small auxin-up RNA (SAUR) genes in moso bamboo (Phyllostachys edulis)

“…The SAUR gene family contains numerous auxin-response genes in different species, including 81 SAURs (with 2 pseudogenes) in Arabidopsis (Hagen and Guilfoyle 2002), 58 SAURs (with 2 pseudogenes) in rice (Jain et al 2006), 18 SAURs in moss (Rensing et al 2008), 71 SAURs in sorghum (Wang et al 2010), 134 SAURs in potato, 99 SAURs in tomato (Wu et al 2012), 79 SAURs in maize (Chen et al 2014) and 70 SAURs in citrus (Xie et al 2015). These reports also reported their main functions in these species.…”

“…One of the vital auxin-responsive families is the small auxin-up RNA (SAUR) gene family. SAUR genes have been identified in mung bean (Yamamoto et al 1992), pea (Guilfoyle et al 1993), tomato (Zurek et al 1994), Arabidopsis (Gil et al 1994), apple (Watillon et al 1998), radish (Ann et al 1998), maize (Yang and Poovaiah 2000), rice (Jain et al 2006b), moss (Rensing et al 2008), sorghum (Wang et al 2010), potato, tobacco, pepper, petunia (Wu et al 2012), cotton (Yang et al 2012), litchi (Kuang et al 2012), peach (Tatsuki et al 2013), poplar ) and citrus (Xie et al 2015). Until now, no SAUR gene had been reported in P. edulis (PheSAUR).…”