Genome-Wide Analysis of SAUR Gene Family Identifies a Candidate Associated with Fruit Size in Loquat (Eriobotrya japonica Lindl.)

Abstract

Fruit size is an important fruit quality trait that influences the production and commodity values of loquats (Eriobotrya japonica Lindl.). The Small Auxin Upregulated RNA (SAUR) gene family has proven to play a vital role in the fruit development of many plant species. However, it has not been comprehensively studied in a genome-wide manner in loquats, and its role in regulating fruit size remains unknown. In this study, we identified 95 EjSAUR genes in the loquat genome. Tandem duplication and segmental duplication contributed to the expansion of this gene family in loquats. Phylogenetic analysis grouped the SAURs from Arabidopsis, rice, and loquat into nine clusters. By analyzing the transcriptome profiles in different tissues and at different fruit developmental stages and comparing two sister lines with contrasting fruit sizes, as well as by functional predictions, a candidate gene (EjSAUR22) highly expressed in expanding fruits was selected for further functional investigation. A combination of Indoleacetic acid (IAA) treatment and virus-induced gene silencing revealed that EjSAUR22 was not only responsive to auxin, but also played a role in regulating cell size and fruit expansion. The findings from our study provide a solid foundation for understanding the molecular mechanisms controlling fruit size in loquats, and also provide potential targets for manipulation of fruit size to accelerate loquat breeding.

Genetic variations in MdSAUR36 participate in the negative regulation of mesocarp cell division and fruit size in Malus species

“…SAUR was one of the early auxin responsive genes with multiple biological functions such as hypocotyl growth, stem elongation, auxin transport and light signaling(Deng et al, 2019). EjSAUR22 played an important role in regulating fruit size via affecting cell expansion, silencing EjSAUR22 led to a small fruit size and small cell size in loquat (Eriobotrya japonica L.)(Peng et al, 2022). In this study, however, we found that MdSAUR36 exhibited an inhibitory effect on mesocarp cell division and thus nal fruit size.…”

Genome-wide identification, characterization, and expression analysis of the small auxin-up RNA gene family during zygotic and somatic embryo maturation of the cacao tree (Theobroma cacao)

“…Interestingly, the chromosomal distributions of the SAUR gene family in the genomes of other higher plant species, such as coffea [19], melon [21], and wax gourd [23] also confirmed our finding. Previously, the SAUR family is being explored in various higher plant species, such as potato [12], tomato [12], watermelon [13], cotton [14], moso bamboo [15], poplar [16], grape [17], apple [18], coffea [19], Chinese white pear [20], melon [21], loquat [22], wax gourd [23], peanut [24], pineapple [25], foxtail millet [26], cucumber [27], and longan [28]. More specifically, 31 and 38 members of the SAUR families have been recorded in coffea and moso bamboo [15,19].…”

“…The high occurrence of intronless genes in the TcSAUR family in cacao could be consistent with the cases reported in other plant species. For example, most SAUR genes in pineapple did not have introns [25], while 85 (out of 95) SAUR genes in loquat also contained no intron [22]. In Chinese white pear, a majority of the SAUR genes were intronless, whereas only five SAUR genes contained at least one intron [20].…”

“…To gain an insight into their functions, previous studies have been performed to analyze the SAUR families in many important crop species, including potato (Solanum tuberosum) and tomato (Solanum lycopersicum) [12], watermelon (Citrullus lanatus) [13], cotton (Gossypium spp.) [14], moso bamboo (Phyllostachys edulis) [15], poplar (Populus trichocarpa) [16], grape (Vitis vinifera) [17], apple (Malus domestica) [18], coffea (Coffea canephora) [19], Chinese white pear (Pyrus bretschneideri) [20], melon (Cucumis melo) [21], loquat (Eriobotrya japonica) [22], wax gourd (Benincasa hispida) [23], peanut (Arachis hypogaea) [24], pineapple (Ananas comosus) [25], foxtail millet (Setaria italica) [26], cucumber (Cucumis sativus) [27], and longan (Dimocarpus longan) [28]. However, this important gene family in cacao has not been recorded, even though the assembly of cacao was released [29].…”

Transcriptomic and Hormone Analyses Provide Insight into the Regulation of Axillary Bud Outgrowth of Eucommia ulmoides Oliver

“…AUX/IAA genes encode transcriptional repressors of auxin-responsive genes, while genes of the GH3 family regulate the auxin pool through negative feedback [ 36 ]. SAUR genes respond rapidly to auxin stimulation and can be transcribed by auxin within minutes without de novo protein synthesis [ 37 ]. In addition, the genes of the YUC family play an important role in IAA biosynthesis to maintain the auxin concentration and regulate plant growth [ 38 ].…”