A combinatorial TRM-OFP module bilaterally fine-tunes tomato fruit shape

Identification of CaPCR1, an OFP gene likely involved in pointed versus concave fruit tip regulation in pepper (Capsicum annuum L.) using recombinant inbred lines

KEY MESSAGE

CaPCR1 (Capana12g002165) was a candidate gene regulating fruit concave/pointed tip shape in pepper. The concave shape of the fruit tip in pepper plants is highly susceptible to drought and low temperature stresses, resulting in the appearance of a pointed tip fruit, which affects its commercial value. However, few studies on the process of fruit tip development and regulatory genes in pepper have been reported. Herein, the developmental process of the ovary before anthesis, especially changes in the shape of the ovary tip, was studied in detail. The results showed that the final fruit tip shape was consistent with the ovary tip shape before anthesis, and a concave tip shape gradually developed. F4 recombinant inbred lines (RILs) were constructed to map the genes regulating fruit tip shape through hybridization of the LRS and SBS pepper inbred lines. CaPCR1 (Capana12g002165), an OFP (OVATE Family Protein) family gene, was located in the candidate region on chr12. Three SNPs were found in the protein coding sequence of CaPCR1 between SBS and LRS, but only one SNP led to amino acid variation. Sequence variations, including base replacements, deletions and insertions, were also detected in the gene promoter region. The relative expression level of the CaPCR1 gene was significantly greater in the concave tip ovary than in the pointed tip ovary. qRT‒PCR analysis revealed that the CaPCR1 gene was expressed mainly in the gynoecium, placenta and green fruit pericarp, which was consistent with its function in ovary and fruit development. Taken together, these results suggested that CaPCR1 is a candidate gene involved in fruit tip shape determination in pepper.

Microtubule-associated proteins MAP65-1 and SUN18/IQD26 coordinately regulate tomato fruit shape by affecting cell division

Microtubule-associated proteins MAP65-1 and SUN18 function additively in fruit shape regulation by modulating cell division patterns but not changing cell morphology.

New Advances in the Study of Regulation of Tomato Flowering-Related Genes Using Biotechnological Approaches

The tomato is a convenient object for studying reproductive processes, which has become a classic. Such complex processes as flowering and fruit setting require an understanding of the fundamental principles of molecular interaction, the structures of genes and proteins, the construction of signaling pathways for transcription regulation, including the synchronous actions of cis-regulatory elements (promoter and enhancer), trans-regulatory elements (transcription factors and regulatory RNAs), and transposable elements and epigenetic regulators (DNA methylation and acetylation, chromatin structure). Here, we discuss the current state of research on tomatoes (2017-2023) devoted to studying the function of genes that regulate flowering and signal regulation systems using genome-editing technologies, RNA interference gene silencing, and gene overexpression, including heterologous expression. Although the central candidate genes for these regulatory components have been identified, a complete picture of their relationship has yet to be formed. Therefore, this review summarizes the latest achievements related to studying the processes of flowering and fruit set. This work attempts to display the gene interaction scheme to better understand the events under consideration.

Leveraging brassinosteroids towards the next Green Revolution

The use of gibberellin-related dwarfing genes significantly increased grain yield during the Green Revolution. Brassinosteroids (BRs) play a vital role in regulating agronomic traits and stress resistance. The potential of BR-related genes in crop improvement has been well demonstrated, positioning BRs as crucial targets for the next agricultural biotechnological revolution. However, BRs exert pleiotropic effects on plants, and thus present both opportunities and challenges for their application. Recent research suggests promising strategies for leveraging BR regulatory molecules for crop improvement, such as exploring function-specific genes, identifying beneficial alleles, inducing favorable mutations, and optimizing spatial hormone distribution. Advancing our understanding of the roles of BRs in plants is imperative to implement these strategies effectively.

Form and contour: breeding and genetics of organ shape from wild relatives to modern vegetable crops

Shape is a primary determinant of consumer preference for many horticultural crops and it is also associated with many aspects of marketing, harvest mechanics, and postharvest handling. Perceptions of quality and preference often map to specific shapes of fruits, tubers, leaves, flowers, roots, and other plant organs. As a result, humans have greatly expanded the palette of shapes available for horticultural crops, in many cases creating a series of market classes where particular shapes predominate. Crop wild relatives possess organs shaped by natural selection, while domesticated species possess organs shaped by human desires. Selection for visually-pleasing shapes in vegetable crops resulted from a number of opportunistic factors, including modification of supernumerary cambia, allelic variation at loci that control fundamental processes such as cell division, cell elongation, transposon-mediated variation, and partitioning of photosynthate. Genes that control cell division patterning may be universal shape regulators in horticultural crops, influencing the form of fruits, tubers, and grains in disparate species. Crop wild relatives are often considered less relevant for modern breeding efforts when it comes to characteristics such as shape, however this view may be unnecessarily limiting. Useful allelic variation in wild species may not have been examined or exploited with respect to shape modifications, and newly emergent information on key genes and proteins may provide additional opportunities to regulate the form and contour of vegetable crops.

Molecular and genetic regulations of fleshy fruit shape and lessons from Arabidopsis and rice

Fleshy fruit shape is an important external quality trait influencing the usage of fruits and consumer preference. Thus, modification of fruit shape has become one of the major objectives for crop improvement. However, the underlying mechanisms of fruit shape regulation are poorly understood. In this review we summarize recent progress in the genetic basis of fleshy fruit shape regulation using tomato, cucumber, and peach as examples. Comparative analyses suggest that the OFP-TRM (OVATE Family Protein - TONNEAU1 Recruiting Motif) and IQD (IQ67 domain) pathways are probably conserved in regulating fruit shape by primarily modulating cell division patterns across fleshy fruit species. Interestingly, cucumber homologs of FRUITFULL (FUL1), CRABS CLAW (CRC) and 1-aminocyclopropane-1-carboxylate synthase 2 (ACS2) were found to regulate fruit elongation. We also outline the recent progress in fruit shape regulation mediated by OFP-TRM and IQD pathways in Arabidopsis and rice, and propose that the OFP-TRM pathway and IQD pathway coordinate regulate fruit shape through integration of phytohormones, including brassinosteroids, gibberellic acids, and auxin, and microtubule organization. In addition, functional redundancy and divergence of the members of each of the OFP, TRM, and IQD families are also shown. This review provides a general overview of current knowledge in fruit shape regulation and discusses the possible mechanisms that need to be addressed in future studies.