Journal of Plant Growth Regulation

Busatto, Nicola; Herrera, Raul

doi: 10.1007/s00344-025-11643-5pmid: N/A

Singh, Lakhwinder; Sadawarti, Ramesh Kumar; Singh, Shailesh Kumar; Shaifali, ; Mirza, Anis Ahmad

doi: 10.1007/s00344-024-11502-9pmid: N/A

Strawberry (Fragaria) is one of the important cash crops cultivated worldwide, belonging to the family Rosaceae, and is an octaploid species (2n = 8x = 56). It bears nutritive fruits which is an excellent source of vitamins, sugars, fibers, minerals, phenolics, flavonoids, and antioxidants. The growth, flowering, fruiting, and fruit quality of strawberries is highly influenced by climatic conditions so the plant growth regulators can modulate crop productivity and fruit quality. PGRs can also manage the expression of intrinsic genetic capability and control the gene expression during translation and transcription. This review paper examines the optimization of plant growth regulators (PGRs) for high productivity of strawberry crops. It delves into the mechanisms of these regulators, their impact on strawberry plant development, and their potential to enhance yield, fruit quality, and sustainability in strawberry farming practices in temperate, tropical, and subtropical climates. The present review article emphasizes the effect of essential plant growth regulators (Gibberellic acid, Triacontanol, Naphthaleneacetic acid, and growth inhibitors) on strawberries’ vegetative growth, yield, and quality. A comprehensive discussion has also been included on the physiological or molecular mechanism of the action of these PGRs.

Muhammad, Noor; Luo, Zhi; Liu, Zhiguo; Liu, Mengjun

doi: 10.1007/s00344-023-11102-zpmid: N/A

The color that results from anthocyanin accumulation has a direct effect on the dietary and market values of fresh fruit. Fruit color pigments such as anthocyanins are produced via the flavonoid pathway, where the biosynthetic genes are coordinatedly regulated by the myeloblastosis, basic helix–loop–helix, and WD40 a beta-transducin repeat, which is a short structural motif consisting of about 40 amino acids that commonly terminating in a tryptophan–aspartic acid (W–D) dipeptide “MYB-bHLH-WD40/WDR” (MBW) regulatory complex. This article discusses the representatives of this regulatory complex, such as bHLH, MYB, WD40, and their regulatory role in fruit coloration. Further, the joint role of MYBs, bHLH TFs, and structural genes has been described in this article. This article will help plant breeders in the future to breed colorful, anthocyanin, and nutrient-rich fruit-bearing plant species.

Gómez-Parada, Claudia; Figueroa, Carlos R.; Lin-Wang, Kui; Moya-León, Alejandra; Espley, Richard V.; Allan, Andrew C.; Herrera, Raul

doi: 10.1007/s00344-024-11281-3pmid: N/A

MYB transcription factors (TFs) are involved in the regulation of flavonoid biosynthesis in both Chilean white strawberry (Fragaria chiloensis) and commercial strawberry (Fragaria × ananassa). There is evidence that MYB1 TF repress anthocyanin biosynthesis, but would also be participating in the regulation of the proanthocyanidin (PA) polymer synthesis, either in the activation or repression of the expression of PA-related genes. We investigated the role of the MYB1 TF in the regulation of the PA-associated structural gene leucoanthocyanidin reductase (LAR). The promoter regions of LAR were isolated from F. chiloensis and F. × ananassa genomes and named as pFcLAR and pFaLAR, respectively. Promoter analysis revealed several putative binding sites for MYBs and bHLH TFs. Then, dual luciferase assays were conducted to investigate whether MYB1 can act as a transactivator of LAR promoters in both species. In the long version of LAR promoters of both species (1381 bp upstream of ATG), the addition of MYB1 to the MYB10-bHLH3 complex repressed the activation. However, when using the medium version of the pFcLAR (815 bp upstream of ATG), MYB1 alone significantly activated the promoter, and no repression was observed when MYB1 was added to the MYB10-bHLH3 complex in the short pFa/FcLAR promoters (316 bp upstream of ATG). We propose that the FcMYB1 TF could regulate PA biosynthesis, and that its role, as either a repressor or activator, is dependent of other partners and the DNA sequence context of the promoter regions.

Fernández-Cancelo, Pablo; Giné-Bordonaba, Jordi; Teixidó, Neus; Alamar, M. Carmen

doi: 10.1007/s00344-024-11270-6pmid: N/A

Three apple cultivars with different peel colour and known ripening dynamics were examined throughout development and on-tree ripening to unravel how the hormonal crosstalk may influence colour changes. Our results indicate that the colour of ripe apples in ‘Granny Smith’ and ‘Opal®’ cultivars was primarily influenced by chlorophyll levels masking the contribution of other pigments, whilst the development of red colour in the ‘Royal Gala’ was not only due to an important loss of chlorophyll during ripening but also to anthocyanins accumulation. The interplay amongst indole-3-acetic acid (IAA), ethylene and abscisic acid (ABA) seemed to control pigment content during the later stages of development, indicating that variations in the hormonal profile contribute to colour differences in ripe apples. In ‘Granny Smith’ apples, basal levels of IAA, ethylene and ABA were associated with the inhibition of chlorophyll loss, which was responsible for its green colour, despite the presence of high carotenoid levels. In contrast, the peel of ‘Opal®’ and ‘Royal Gala’ apples underwent a degreening process facilitated by the IAA-mediated activation of ethylene metabolism, in a crosstalk facilitated by MdARF5. The accumulation of anthocyanins in the peel of ‘Royal Gala’ apples seemed to be regulated in an ethylene-dependent manner, with MdMYB1 acting as the mediator between ethylene signalling and the anthocyanins biosynthesis and vacuolar transport pathways. On the other hand, the decline in carotenoid content during fruit development in the three cultivars appeared to be regulated at the catabolic level through ABA and its derivatives and possibly also facilitated by ethylene-mediated mechanisms. Notably, chlorophyll levels, crucial for the observed colour changes, were likely controlled by MdGLK1, a transcription factor involved in chloroplast biogenesis, working in coordination with ethylene-dependent catabolic enzymes. Overall, understanding the cultivar-specific hormonal regulation of apple colour provides valuable insights for developing preharvest and postharvest strategies to ensure an optimal fruit colour aligned with consumer preferences.

Kmeli, Narjes; Bettaieb, Inchirah; Hamdi, Jihen; Mlouka, Rania; Gaaied, Sonia; Chatti, Khaled; Bouktila, Dhia

doi: 10.1007/s00344-023-11151-4pmid: N/A

WRKY transcription factors (TFs) play significant roles in plant development. However, they have not yet been studied in terms of the impact they have on the common fig (Ficus carica L.), a significant fruit species in Mediterranean countries. In this study, we extensively examined the full-genome F. carica WRKY (FcWRKYs) gene complement (47 genes), in terms of gene structure, protein domains and motifs, physicochemical properties, phylogenetic relationships and selection pressure. Based on the structural properties of the encoded proteins, we grouped the FcWRKY genes into three main groups (I, II and III), with the second group being further divided into five subgroups (a–e). Subgroup IId FcWRKY proteins were discovered to contain the Plant zinc cluster (Plant-zn-clust) domain and Ca2+-dependent Calmodulin (CaM)-binding domain (CaMBD). In total, we discovered ten conserved motifs, seven of which may be associated with WRKY functional specificities attributable to a single group or a small number of groups. Phylogenetically related members shared similar exon–intron structure, with the average number of exons being higher (~ 5) in (sub)groups I, IIa, IIb compared to IIc, IId, IIe and III (~ 3). Comparative phylogeny using the mulberry WRKY gene complement (MnWRKYs) revealed 38 pairs of orthologous genes shared by both species, which diverged from 84.3 to 25.3 million years ago (Mya) and have been evolving under purifying selection that was weaker on group III genes, suggesting an important role of this group in the enlargement of the adaptive array of WRKY TFs. RNA-seq results revealed that genes that were highly expressed in the peel across all fruit developmental stages belonged to group I and subgroups IIb, IIc, IId and IIe, suggesting the role played by these members in fruit peel development. RT-qPCR validated this profile and further showed that three genes FcWRKY25 (IIc), FcWRKY31 (IIb), and FcWRKY39 (IIc) are clearly more overexpressed during color acquisition in the Tunisian dark cultivar ‘Zidi’, in comparison with the light purple cultivar ‘Soltani’, presenting these three genes as potential contributors to the changes in biochemical compounds in the fig peel during fruit maturation. The knowledge framework provided by our study will be a valuable asset in the functional exploration of candidate genes that may be associated with fruit quality.

Cao, Suhao; Guo, Zhihua; Liu, Hong; Qi, Kaijie; Xie, Zhihua; Tian, Ruiping; Gu, Chao; Zhang, Shaoling

doi: 10.1007/s00344-024-11248-4pmid: N/A

Phytohormone ethylene is one of the important plant hormones that regulate fruit development and ripening. The transcription regulation of ethylene biosynthesis has been extensively studied in fleshy fruit, but the role of auxin/indole-3-acetic acid (Aux/IAA) in ethylene biosynthesis is still unknown. In this study, based on the genome-wide expression analyses of pear Aux/IAA genes, we found that PbIAA.C3 had a higher expression level in ripening fruits than in developing fruits in all 13 tested pear cultivars. Over-expression of PbIAA.C3 increased ethylene production, while silencing of PbIAA.C3 decreased ethylene production in pear fruit. This result indicates that PbIAA.C3 positively regulates ethylene biosynthesis during fruit ripening. Dual-luciferase assay showed that PbIAA.C3 could enhance the activity of the 1-aminocyclopropane1-carboxylate synthase PbACS1b expression by binding to the upstream region from − 2000 to − 1500 bp of the initiation codon of PbACS1b to increase the expression level. However, the transcription activation of PbIAA.C3 was repressed by the auxin-responsive factor PbARF32 which physically interacted with PbIAA.C3. Therefore, PbARF32 may be also involved in ethylene biosynthesis in pear fruit via the PbIAA.C3–PbARF32 interaction. The information provided new insights into the molecular regulation of ethylene biosynthesis during fruit ripening.

Kuhn, Nathalie; Arellano, Macarena; Ponce, Claudio; Hodar, Christian; Correa, Francisco; Multari, Salvatore; Martens, Stefan; Carrera, Esther; Donoso, José Manuel; Meisel, Lee A.

doi: 10.1007/s00344-024-11340-9

Vittani, Lorenzo; Populin, Francesca; Stuerz, Stefan; Fava, Federico; Robatscher, Peter; Zanella, Angelo; Costa, Fabrizio; Busatto, Nicola

doi: 10.1007/s00344-024-11247-5pmid: N/A

After harvest fruit are stored to preserve the quality features established during the on-tree development and maturation, ensuring thus a continuous availability of fresh fruit on the market. For certain fruit species like apple, storage can last for almost a year, especially when coupled with several strategies, such as the reduction of the oxygen concentration or the application of ethylene competitor molecules, like 1-methylcyclopropene (1-MCP). To guarantee the maintenance of the highest quality, the monitoring of the physiological processes ongoing during the postharvest ripening is compelling. For this purpose, 16 genes belonging to key fruit ripening pathways, such as the ethylene and the sugar/fermentation metabolism, have been chosen as potential markers for the molecular characterization of the major changes occurring in the fruit during storage. Among these genes, ACS, PPO, PG1, RAP2-like, and ADH exhibited the most significant differential expression across the various samples. Based on the transcriptional pattern, this set of genes constitutes a valuable molecular tool for a precise and reliable RNA-based monitoring of the postharvest ripening progression and fermentation process in apples. PPO, together with S6PDH, were furthermore employed to inspect the onset of the superficial scald in apple and resulted to correlate with the evaluation of the incidence of this disorder and the accumulation of the sugar alcohol sorbitol, known to play important protecting roles to chilling injuries. The assessment of the transcriptional signature of these elements can facilitate the development of gene expression markers suitable for a more informed investigation of the physiological progression of the postharvest ripening in apples, ultimately leading to the promotion of high-quality stored apples, extending storage time while minimizing postharvest disorders and fruit loss.

Corpas, Francisco J.; Muñoz-Vargas, María A.; González-Gordo, Salvador; Rodríguez-Ruiz, Marta; Palma, José M.

doi: 10.1007/s00344-023-11150-5pmid: N/A

Storage and maintenance of horticultural products in optimal conditions for a reasonable period, once they have been harvested is a technological challenge. Diverse methods are generally used, i.e., low temperature but, in many cases, it may provoke undesirable collateral effects such as softening or promoting pathogens infections, thus causing their deterioration. Nitric oxide (·NO) and hydrogen sulfide (H2S) are compounds generated endogenously by plants with signaling properties that mediate fruit development and ripening. Additionally, when these molecules are applied exogenously, they can provide benefits such as maintaining the quality of horticultural products and even prolonging their shelf-life once they are stored. This review provides a broad perspective of ·NO and H2S metabolism in plant cells and, in addition, different plant models are described of how the exogenous application of either NO or H2S to horticultural products preserves nutritional quality during postharvest storage.Graphical Abstract[graphic not available: see fulltext]