Planta

Yu, Pei; Shinde, Harshraj; Dudhate, Ambika; Kamiya, Takehiro; Gupta, Shashi Kumar; Liu, Shenkui; Takano, Tetsuo; Tsugama, Daisuke

doi: 10.1007/s00425-024-04574-0pmid: 39549089

Gkanogiannis, Anestis; Rahman, Hifzur; Singh, Rakesh Kumar; Lopez-Lavalle, Augusto Becerra

doi: 10.1007/s00425-024-04551-7pmid: 39443340

Main conclusionThe chromosome-level genome assembly of Citrullus colocynthis reveals its genetic potential for enhancing drought tolerance, paving the way for innovative crop improvement strategies.AbstractThis study presents the first comprehensive genome assembly and annotation of Citrullus colocynthis, a drought-tolerant wild close relative of cultivated watermelon, highlighting its potential for enhancing agricultural resilience to climate change. The study achieved a chromosome-level assembly using advanced sequencing technologies, including PacBio HiFi and Hi-C, revealing a genome size of approximately 366 Mb with low heterozygosity and substantial repetitive content. Our analysis identified 23,327 gene models, that could encode stress response mechanisms for species’ adaptation to arid environments. Comparative genomics with closely related species illuminated the evolutionary dynamics within the Cucurbitaceae family. In addition, resequencing of 27 accessions from the United Arab Emirates (UAE) identified genetic diversity, suggesting a foundation for future breeding programs. This genomic resource opens new avenues for the de novo domestication of C. colocynthis, offering a blueprint for developing crops with enhanced drought tolerance, disease resistance, and nutritional profiles, crucial for sustaining future food security in the face of escalating climate challenges.

Chen, Lulu; Wang, Run; Hu, Xiaoqing; Wang, Dan; Wang, Yuexia; Xue, Ruili; Wu, Mingzhu; Li, Hua

doi: 10.1007/s00425-024-04559-zpmid: 39466433

Main conclusionTaZAT8-5B, a C2H2 zinc finger protein transcription factor, positively regulates drought tolerance in transgenic Arabidopsis. It promotes root growth under drought stress via the Aux/IAA-ARF module in the auxin signaling pathway.AbstractC2H2 zinc finger proteins (C2H2-ZFPs) represent the largest but relatively unexplored family of transcription factors in plants. This is particularly evident in wheat, where the functions of only a few C2H2-ZFP genes have been confirmed. In this study, we identified a novel C2H2-ZFP gene, TaZAT8-5B. This gene shows high expression in roots and flowers and is significantly induced by heat, drought, and salt stress. Under drought stress, overexpressing TaZAT8-5B in Arabidopsis resulted in increased proline content and superoxide dismutase (SOD) activity in leaves. It also led to reduced stomatal aperture and water loss, while inducing the expression of P5CS1, RD29A, and DREB1A. Consequently, it alleviated drought stress-induced malondialdehyde (MDA) accumulation and improved drought tolerance. Additionally, TaZAT8-5B promoted lateral root initiation under mannitol stress and enhanced both lateral and primary root growth under long-term drought stress. Moreover, TaZAT8-5B was induced by indole-3-acetic acid (IAA). Overexpressing TaZAT8-5B under drought stress significantly inhibited the expression of auxin signaling negative regulatory genes IAA12 and IAA14. Conversely, downstream genes (ARF7, LBD16, LBD18, and CDKA1) of IAA14 and IAA12 were upregulated in TaZAT8-5B overexpressing plants compared to wild-type (WT) plants. These findings suggest that TaZAT8-5B regulates root growth and development under drought stress via the Aux/IAA-ARF module in the auxin signaling pathway. In summary, this study elucidates the role of TaZAT8-5B in enhancing drought tolerance and its involvement in root growth and development through the auxin signaling pathway. These findings offer new insights into the functional analysis of homologous genes of TaZAT8-5B, particularly in Gramineae species.

Wurlitzer, Wesley Borges; Schneider, Julia Renata; Silveira, Joaquim A. G.; de Almeida Oliveira, Maria Goreti; Labudda, Mateusz; Chavarria, Geraldo; Weber, Ani Caroline; Hoehne, Lucélia; Pinheiro, Gizele Martins; Vinhas, Naiara Nunes; Rodighero, Luana Fabrina; Ferla, Noeli Juarez

Zou, Zhi; Fu, Xiaowen; Huang, Jiaquan; Zhao, Yongguo

doi: 10.1007/s00425-024-04553-5pmid: 39438351

Main conclusionCeOLE6, a tuber-specific gene in tigernut, encodes a diverged SH oleosin that functions in oil accumulation via homo and heteromultimerization.AbstractTigernut (Cyperus esculentus L.) is a rare example accumulating high levels of triacylglycerols (TAGs) in underground tubers; however, the mechanism underlying is poorly understood. Given essential roles of oleosins (OLEs) in oil accumulation, in this study, structural and functional analyses were conducted for CeOLE6, an oleosin gene preferentially expressed in tigernut tubers. Phylogenetic analysis revealed that CeOLE6 encodes a diverged oleosin in Clade SH, which also includes CeOLE4 and -5. Further synteny analysis and sequence comparison indicated that CeOLE6 is more likely to be a whole-genome duplication (WGD) repeat of CeOLE4, which underwent rapid evolution and deletion of the typical C-terminal insertion for SHs. Nevertheless, CeOLE6 retains the capacity of oligomerization and oil accumulation, because (i) CeOLE6 could not only interact with itself but also with CeOLE2 and -5, two tuber-dominant members belonging to Clades SL and SH, respectively, and (ii) overexpressing CeOLE6 in tobacco leaves could significantly enhance the TAG content. Though CeWRI1 exhibits a similar expression pattern as CeOLE6 during tuber development, both CeWRI1 and -3 could not activate the CeOLE6 promoter, implying that they are not transcription factors contributing tuber-specific activation of CeOLE6. These findings not only provide insights into CeOLE genes in tuber oil accumulation, but also lay a foundation for further genetic improvement in tigernut and other species.

Fernandes, Telma; Gonçalves, Nuno M.; Matiolli, Cleverson C.; Rodrigues, Mafalda A. A.; Barros, Pedro M.; Oliveira, M. Margarida; Abreu, Isabel A.

doi: 10.1007/s00425-024-04565-1pmid: 39514093

Main conclusionSUMOylation of SLR1 at K2 protects productivity under salt stress, possibly by modulation of SLR1 interactome.AbstractDELLA proteins modulate GA signaling and are major regulators of plant plasticity to endure stress. DELLAs are mostly regulated at the post-translational level, and their activity relies on the interaction with upstream regulators and transcription factors (TFs). SUMOylation is a post-translational modification (PTM) capable of changing protein interaction and has been found to influence DELLA activity in Arabidopsis. We determined that SUMOylation of the single rice DELLA, SLENDER RICE1 (SLR1), occurs in a lysine residue different from the one identified in Arabidopsis REPRESSOR OF GA (RGA). Artificially increasing the SUMOylated SLR1 levels attenuated the penalty of salt stress on rice yield. Gene expression analysis revealed that the overexpression of SUMOylated SLR1 can regulate GA biosynthesis, which could partially explain the sustained productivity upon salt stress imposition. Furthermore, SLR1 SUMOylation blocked the interaction with the growth regulator YAB4, which may fine-tune GA20ox2 expression. We also identified novel SLR1 interactors: bZIP23, bHLH089, bHLH094, and OSH1. All those interactions were impaired in the presence of SUMOylated SLR1. Mechanistically, we propose that SUMOylation of SLR1 disrupts its interaction with several transcription factors implicated in GA-dependent growth and ABA-dependent salinity tolerance to modulate downstream gene expression. We found that SLR1 SUMOylation represents a novel mechanism modulating DELLA activity, which attenuates the impact of stress on plant performance.

Batyrshina, Zhaniya; Block, Anna K.; Basset, Gilles J.

doi: 10.1007/s00425-024-04572-2pmid: 39560789

Main conclusionThe contribution of p-coumarate β-oxidation and kaempferol cleavage to the pools of glycosylated, free and cell wall-bound 4-hydroxybenzoate is organ-dependent in Arabidopsis.Abstract4-Hydroxybenzoate (4-HB) is a vital precursor for a number of plant primary and specialized metabolites, as well as for the assembly of the plant cell wall. In Arabidopsis, it is known that 4-HB is derived independently from phenylalanine and tyrosine, and that the metabolism of phenylalanine into 4-HB proceeds via at least two biosynthetic routes: the β-oxidation of p-coumarate and the peroxidative cleavage of kaempferol. The precise contribution of these precursors and branches to 4-HB production, however, is not known. Here, we combined isotopic feeding assays, reverse genetics, and quantification of soluble (i.e., free and glycosylated) and cell wall-bound 4-HB to determine the respective contributions of phenylalanine, tyrosine, β-oxidation of p-coumarate, and peroxidative cleavage of kaempferol to 4-HB biosynthesis in Arabidopsis tissues. Over 90% of 4-HB was found to originate from phenylalanine in both leaves and roots. Soluble 4-HB level varied significantly between organs, while the proportion of cell wall-bound 4-HB was relatively constant. In leaves and flowers, glycosylated and cell wall-bound 4-HB were the most and least abundant forms, respectively. Flowers displayed the highest specific content of 4-HB, while free 4-HB was not detected in roots. Although p-coumarate β-oxidation and kaempferol catabolism were found to both contribute to the supply of 4-HB in all tissues, the proportion of kaempferol-derived 4-HB was higher in roots than in leaves and flowers. Within the β-oxidative branch, p-coumaroyl-CoA ligase 4-CL8 (At5g38120) bore a preponderant role in the production of soluble and cell wall-bound 4-HB in leaves, while p-coumaroyl-CoA ligase At4g19010 appeared to control the biosynthesis of soluble 4-HB in flowers. Furthermore, analysis of a series of Arabidopsis T-DNA mutants corresponding to the three major UDP-glucosyltransferases known to act on 4-HB in vitro (UGT75B1, UGT89B1, and UGT71B1) showed that none of these enzymes appeared in fact to have a significant role in the glycosylation of 4-HB in vivo.

Liu, Yingxiang; Zhou, Wenyan; He, Mingliang; Sui, Jingjing; Tian, Xiaojie; Guan, Qingjie; Yu, Xinglong; Li, Kun; Bu, Qingyun; Li, Xiufeng

doi: 10.1007/s00425-024-04570-4pmid: 39546003

Mishra, Gayatri; Mahapatra, Subrat Kumar; Rout, Gyana Ranjan

doi: 10.1007/s00425-024-04568-ypmid: 39527315

Kolomeitseva, Galina L.; Ryabchenko, Andrey S.; Babosha, Alexander V.; Koval, Vladimir A.

doi: 10.1007/s00425-024-04569-xpmid: 39557703

Main conclusionDuring evolution, similar vectors of adaptive radiation may have evolved in the subtribe Malaxidinae. This was manifested in homologous series of variability in suspensor shape and seed coat ultrasculpture in clades of terrestrial and epiphytic orchids.AbstractThe present study examines the variability of embryonic traits across clades and subclades of subtribe Malaxidinae (Orchidaceae), previously identified by molecular genetic data. Ovules and seeds from fruits of orchids of the genera Crepidium, Liparis (sections Cestichis and Blepharoglossum), Dienia, and Oberonia were examined by confocal laser microscopy with fluorescent dye staining. The branched or rounded suspensor in the studied species was unicellular and originated from the nondividing basal cell cb. The elongated or flattened transmission structure of one or two cells was located at the junction of the suspensor and the embryo proper. Two species (Oberonia gammiei and Liparis elliptica) were found to have unitegmal ovules. Three morphological groups of seeds were identified based on the shape and sculpture of the periclinal cell wall. A comparative analysis of the embryological characters in Malaxidinae species reveals that the lobed suspensor is a homoplasy present in different subclades of terrestrial and epiphytic orchids. The flat transmission cell is an apomorphy in the Cestichis subclade. Similarly, the independent formation of the unitegmal ovule occurred in two subclades of epiphytic orchids. The results of our study suggest that similar adaptive radiation vectors may have evolved in the subtribe Malaxidinae in the orchids we studied.