Suppression of the D-class MADS-box AGL11 gene triggers seedlessness in fleshy fruits

Abstract

Seedlessness, one of the most desired traits in fleshy fruits, can be obtained altering solely AGL11 gene, a D -class MADS-box. Opposite to overlapping functions described for ovule identity. AGAMOUS like-11 (AGL11) is a D-class MADS-box gene that determines ovule identity in model species. In grapevine, VviAGL11 has been proposed as the main candidate gene responsible for seedlessness because ovules develop into seeds after fertilization. Here, we demonstrate that AGL11 has a direct role in the determination of the seedless phenotype. In grapevine, broad expression analysis revealed very low expression levels of the seedless allele compared to the seeded allele at the pea-size berry stage. Heterozygous genotypes have lower transcript accumulation than expected considering the diploid nature of grapevine, thereby revealing that the dominant phenotype previously described for seedlessness is based on its expression level. In a seeded somatic variant of Sultanina (Thompson Seedless) that has well-developed seeds, Sultanine Monococco, structural differences were identified in the regulatory region of VviAGL11. These differences affect transcript accumulation levels and explain the phenotypic differences between the two varieties. Functional experiments in tomato demonstrated that SlyAGL11 gene silencing produces seedless fruits and that the degree of seed development is proportional to transcript accumulation levels. Furthermore, the genes involved in seed coat development, SlyVPE1 and SlyVPE2 in tomato and VviVPE in grapevine, that are putatively controlled by SlyAGL11 and VviAGL11, respectively, are expressed at lower levels in silenced tomato lines and in seedless grapevine genotypes. In conclusion, this work provides evidence that the D-class MADS-box AGL11 plays a major and direct role in seed development in fleshy fruits, providing a valuable tool for further analysis of fruit development.

Identification, characterization and functional analysis of AGAMOUS subfamily genes associated with floral organs and seed development in Marigold (Tagetes erecta)

“…However, in stk single mutant, only the ovule funiculus is larger than that of the wild type, and the mature seeds are not detached from the silique [24][25][26][27]. In addition, the similar phenotype changes have been reported in cultivated Grapevine (Vitis vinifera) [28] and Populus [2], indicating that STK/AGL11 has a conservative function in regulating the ovule development.…”

Unraveling the Deep Genetic Architecture for Seedlessness in Grapevine and the Development and Validation of a New Set of Markers for VviAGL11-Based Gene-Assisted Selection

“…It has recently been reported [16] that a mutation (Arg-197-Leu substitution) in exon 7 of the coding sequence of the VviAGL11 gene, previously identified and mistakenly reported as non-causal [9], is fully linked to stenospermocarpy. Silencing of the heterologous gene to VviAGL11 in Solanum lycopersicum produces seedlessness [17], and the ectopic expression of VviAGL11 in Arabidopsis AGL11 mutant restores the wild type phenotype and confirms its role in seed morphogenesis [18]. Both works support, at a functional level, VviAGL11 as the main gene responsible for seedlessness.…”

“…Based on a preliminary diversity analysis with the SSR p3_VvAGL11 of a collection of breeding material from INIA and CREA, we defined the existence of at least 10 VviAGL11 alleles at the promoter level, including the reference allele from Pinot Noir PN40024, the most common seeded allele (186 bp), and the unique seedless allele (196 bp) described earlier [9]. For each allele, a 3 kb regulatory region of VviAGL11 was isolated using the primers pVviAGL11-F and pVviAGL11-R described previously [17]. The PCR was performed using the Phusion High-Fidelity DNA Polymerase (New England Biolabs) following the manufacturer's instructions.…”

Genome-wide identification of pistil-specific genes expressed during fruit set initiation in tomato (Solanum lycopersicum)

“…For example, Arabidopsis type-I AGAMOUS-LIKE61 ( AGL61 ) /DIANA ( DIA ) is expressed exclusively in the central cell and early endosperm and plays crucial role in endosperm development after fertilization through transcriptional control in the central cells [79–82]. AtAGL62 also plays important role in the endosperm and seed coat development [83–85]. Gene expression analysis using tissue-specific transcriptome data from wild tomato S .…”