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[学术文献 ] Brassinosteroids enhance gibberellic acid biosynthesis to promote cotton fibre cell elongation 进入全文
PLANT BIOTECHNOLOGY JOURNAL
Cotton serves as not only a crucial natural textile crop, with cotton fibre accounting for approximately 95% of fibre usage in the textile industry but also a valuable model for the investigation of plant cell elongation (Cao et al., 2020; Wang et al., 2019). The plant hormones brassinosteroid (BR) and gibberellic acid (GA) promote fibre cell development (He et al., 2024; Huang et al., 2021; Shan et al., 2014; Zhu et al., 2023). Despite the positive role of BR and GA in fibre cell development that has been reported, the cross-talk between BR and GA biosynthesis pathway and signalling pathway in fibre growth remains largely unknown. In this study, our results reveal that BR stimulates GA biosynthesis during fibre elongation in cotton. BR and GA considerably promote cotton fibre development, whereas their respective inhibitors, brassinazole (BRZ, a BR biosynthesis inhibitor) and paclobutrazol (PAC, a GA biosynthesis inhibitor), impede fibre growth (Yang et al., 2023; Zhu et al., 2022). To explore the potential regulatory mechanisms between BR and GA, we treated wild-type (WT) ovules to with BR, BRZ, GA3, and PAC using an in vitro ovule culture system. Our observations reveal that BR and GA improved fibre development, and BRZ and PAC impeded it. In addition, GA3 mitigated the inhibitory effects of BRZ on fibre development, whereas PAC treatment considerably inhibited the fibre-promoting effect of BR. Moreover, the GA levels were increased after the BR treatment and decreased after the BRZ treatment (ovule with fibres). BES1 (Gh_D02G0939) is the critical regulator in BR signalling (Zhu et al., 2023). Overexpression of BES1 notably stimulated the GA content in fibres, accompanied with the considerably increased fibre length . PAC significantly inhibited the promotion of fibre length after BES1 overexpression. These results suggest that BR acts upstream of GA in the context of fibre development. In upland cotton, we identified 26 GA synthesis genes and 15 of them harboured BES1 binding site (E-box cis-element) in their promoters. The interaction between BES1 and 15 candidate gene promoters was investigated using yeast one-hybrid assay. As a result, BES1 was able to interact with two gene promoters (pGA20OX1D and pGA3OX1D). The tobacco dual-luciferase assay demonstrated that BES1 activated the promoters of GA20OX1D and GA3OX1D, which resulted in enhanced expression of LUC gene. The promoters of GA20OX1D and GA3OX1D were segmented into three fragments based on the distribution of E-box cis-elements. BES1 was found to specifically bind to the P2 and F3 fragments of the GA20OX1D and GA3OX1D promoters, respectively. Notably, this binding interaction was abolished upon mutation of the first E-box within the P2 or F3 fragments. Furthermore, the electrophoretic mobility shift assay revealed the specific binding affinity of BES1 to pGA20OX1D-L1 and pGA3OX1D-L2 fragments with the E-box. In addition, competitive binding probes, without biotin, considerably reduced the binding of BES1 protein to pGA20OX1D-L1 and pGA3OX1D-L2, respectively. Moreover, chromatin immunoprecipitation (ChIP) followed by sequencing and ChIP-quantitative PCR (qPCR) analysis demonstrated that BES1 was selectively recruited to the promoter fragments that contain the E-box. The expression levels of GA20OX1D and GA3OX1D in fibres were significantly increased after BR treatment or overexpression of BES1, and decreased after BRZ treatment or knockout of BES1. Furthermore, the expression levels of GA20OX1D and GA3OX1D were increased during cotton fibre development, suggesting the functional roles of these genes in fibre cell development. To further investigate the roles of GA20OX1D and GA3OX1D in cotton fibre development, GA20OX1D and GA3OX1D transgenic cotton plants were generated. Furthermore, we detected the GA content in GA20OX1D and GA3OX1D transgenic cotton fibres and found that overexpression of GA20OX1D or GA3OX1D increased GA accumulation. The fibre length was substantially increased in GA20OX1D or GA3OX1D overexpression plants and significantly decreased in knockout lines. In addition, the cell wall thickness of fibres was largely enhanced in GA3OX1D overexpression lines and reduced in GA3OX1D knockout lines. However, the cell wall thickness of fibres from GA20OX1D transgenic lines was comparable with that from WT plants. More importantly, exogenous application of GA3 successfully rescued the short fibre phenotype resulted from the mutation of GA20OX1D or GA3OX1D. Conversely, PAC inhibited the promotion of fibre elongation led by the overexpression of GA20OX1D or GA3OX1D. Previous studies indicate that GA facilitates cotton fibre elongation by enhancing the biosynthesis of very long-chain fatty acids (VLCFAs) (He et al., 2024; Tian et al., 2022; Xiao et al., 2016). We speculate that GA20OX1D and GA3OX1D may enhance fibre elongation by regulating the biosynthesis of VLCFAs. Collectively, our results illustrate that BR modulates the transcription of GA20OX1D and GA3OX1D via BES1, which in turn regulates GA biosynthesis to facilitate fibre development.
[前沿资讯 ] Calyx Cotton pioneers sustainable textile production in the UK 进入全文
UKFT
UKFT member Calyx Cotton presents an alternative to conventional field-grown cotton, focussing on reducing water consumption and reliance on chemical inputs, ensuring the production is circular and traceable, whilst maintaining high-quality cotton. Based in the south of England, Calyx Cotton tackles the environmental challenges of cotton production by taking a sustainable approach, prioritising people and planet. Traditional cotton production is one of the most water-intensive crops globally, consuming an average of 10,000 litres to produce a single kilogram of fibre. Calyx Cotton employs advanced, closed-loop greenhouse systems that require 97% less water, resulting in a total water usage of c415 litres per kilogram. This reduction has been achieved through a combination of precision irrigation, humidity control and water recapture techniques, in which establishing a new standard for sustainable cotton production. The average t-shirt uses 2,700 litres of water, versus 83 litres with Calyx Cotton. Calyx Cotton’s unique approach to cotton production presents environmental advantages that extend beyond water conservation. Conventional cotton farming heavily relies on pesticides and synthetic fertilisers, contributing to soil degradation and biodiversity loss. By cultivating its cotton within controlled environments, Calyx Cotton has eliminated the need for chemical inputs. Paul Cackett, Co-Founder of Calyx Cotton says: “Our approach allows us to cultivate high-quality fibre without the detrimental side effects typically associated with cotton production, it’s about proving that fashion and sustainability don’t have to be mutually exclusive” Cristyn Bevan, Co-Founder of Calyx Cotton, on the journey to create Calyx Cotton: “Years of meticulous cultivation and greenhouse optimisation have culminated in the development of Calyx Cotton, a sustainable and consistently superior fibre. Our dedication to fine-tuning growing conditions, from selecting the right seed varieties to grow and ultimately breed from, to optimising our controlled climates, has enabled us to produce a cotton fibre that meets the highest quality standards” Calyx Cotton is not just about reducing environmental impact, it is about fostering transparency and trust. Each fibre of Calyx Cotton can be traced back to the specific site where it was cultivated, allowing consumers to make conscious purchasing decisions. Tackling the challenges of climate change and source scarcity, Calyx Cotton presents a scalable and circular solution: “The future of cotton lies not in traditional farming practices but in innovative, controlled growing systems like ours. These systems enable us to minimise resource consumption and maximise quality season after season, contributing to a more sustainable and resilient cotton industry” Calyx Cotton vs. Conventional Cotton Water Efficiency: Calyx Cotton requires significantly less water compared to traditional cotton cultivation. It consumes approximately c415 litres per kilogram, whereas field-grown cotton consumes up to 10,000 litres per kilogram. Pesticide Reduction: Calyx Cotton cultivation eliminates the need for pesticides, resulting in a zero-pesticide footprint. Traditional cotton farming, on the other hand, can use up to 1.8 kilograms of pesticides per hectare. Traceability: Calyx Cotton offers unparalleled traceability, ensuring complete transparency from the growth site to the final fibre.
[学术文献 ] Analysis of Mitochondrial Sequence Deletion in the atp9 5′UTR Region and Design of Molecular Markers in Cotton (Gossypium spp.) 进入全文
PLANT BREEDING
Cotton (Gossypium) is the most important fibre crop in the world, consisting of 45 diploid and 7 tetraploid cotton species. These cotton varieties are valuable for breeding, but their molecular identification methods still need further study. We identified an insert/deletion site (AATTT) at the atp9 5 ' UTR region in the mitochondrial genome of cotton, which could be used to distinguish different cotton species. In this study, the target fragments of 33 cotton species (29 diploid and 4 tetraploid species) were amplified by PCR, and the PCR products potentially containing an EcoR I restriction site were subsequently digested and analysed. The sequencing results revealed that 27 out of 33 cotton species lacked 'AATTT' sequences, while six cotton species (G. longicalyx, G. hirsutum, G. barbadense, G. tomentosum, G. mustillinum and G. darwinii) were found to possess the sequences. Additionally, 39 SNPs were found in this region, and specific molecular markers for G. stocksii, G. bickii and E-genome were developed, respectively. The comparative analysis of mitochondrial sequences from diploid and tetraploid cotton species elucidated their genetic diversity and evolutionary relationships, and species-specific markers were able to discriminate among these species, thereby provided a foundation for more targeted use of wild genetic resources in cotton improvement and efforts to ensure their conservation.
[学术文献 ] Development of a set of monosomic alien addition lines from Gossypium raimondii in Gossypium hirsutum toward breeding applications in cotton 进入全文
BMC PLANT BIOLOGY
Gossypium raimondii Ulbr is a diploid wild cotton (2n = 26, D5D5) that originated in west-central Peru of South America and possesses desirable characteristics that are absent in the Upland cotton G. hirsutum. Many beneficial genes were lost from G. hirsutum in the process of domestication, leading to a narrowed genetic base and greater vulnerability to biotic and abiotic stresses. This genetic base can be expanded through distant hybridization using the superior genes of G. raimondii. In this study, putative hexaploid F1 plants of G. hirsutum - G. raimondii were generated by interspecific hybridization. Analysis of its mitotic metaphase plates revealed the presence of 78 chromosomes, with each of the six chromosome-specific fluorescence in situ hybridization (FISH) probes (3D5, 5D5, 6D5, 7D5, 9D5, and 10D5) of G. raimondii exhibiting bright and distinct signals on its respective pair of chromosomes. Then, the fertile hexaploid F1 plants were continuously backcrossed with G. hirsutum and a set of G. hirsutum - G. raimondii monosomic alien addition lines (MAALs) were developed using SSR markers in successive backcrosses and self-crossing from BC2F1 to BC4F2. These MAALs were confirmed by chromosome-specific anchored SSRs and FISH. This set of MAALs exhibited abundant variation in morphological traits, agronomic characteristics, yield, and fiber quality traits, as well as in drought and salt resistance at seedling stage. Notably, MAAL_9D5 and MAAL_10D5 demonstrated excellent fiber length (FL), fiber uniformity (FU), fiber strength (FS), micronaire value, and fiber elongation (FE); At seeding stage, MAAL_8D5, MAAL9D5, MAAL_10D5, MAAL_12D5, and MAAL_13D5 showed salt resistance potential; while MAAL_1D5, MAAL_3D5, MAAL_4D5, MAAL_7D5, MAAL_8D5, MAAL_12D5, and MAAL_13D5 exhibited drought resistance potential. These MAALs will provide important genetic bridge materials for gene transfer from G. raimondii as well as for the study of Gossypium species genomes and their evolution. A set of Gossypium hirsutum - Gossypium raimondii MAALs were developed and they showed abundant variation in morphological, agronomic, yield, and fiber quality traits, as well as in drought and salt resistance at seedling stage.
[学术文献 ] A MADS-box protein GhAGL8 promotes early flowering and increases yield without compromising fiber quality in cotton 进入全文
INDUSTRIAL CROPS AND PRODUCTS
Flower bud formation is a critical stage of transition from vegetative to reproductive growth, which affects time of flowering and maturing in cotton (Gossypium hirsutum L.). However, the regulatory mechanisms of this process are poorly understood in cotton. To identify the genes involved in the regulation of flower bud formation, this study compared transcriptomes of an early-maturing cotton Zhongmian 619 and a late-maturing cotton 'Texas Marker-1'. An AGAMOUS-LIKE 8 (GhAGL8) gene is highly expressed in the stem apex meristem at the early stage of flower bud of Zhongmian 619 plants. Additionally, GhAGL8 consistently had higher expression levels in several tested early-maturing cultivars compared with late-maturing cultivars at the seedling stage. To assess the role of GhAGL8 in bud formation, the GhAGL8-deficient ghagl8 mutant and GhAGL8-overexpressing (GhAGL8OE) transgenic plants were generated. The ghagl8 plants flowered later while GhAGL8-OE plants flowered earlier than the wild-type plants. Overexpressing GhAGL8_D03 in Arabidopsis thaliana (L). also induced early bolting and flowering. Further investigation revealed that GhAGL8 binds to the CArG-box motifs in the promoter of TERMINAL FLOWER 1 (GhTFL1) gene, a key negative regulatory factor in the flowering pathway, and represses transcription of GhTFL1. GhAGL8 is also synchronously expressed with CAULIFLOWER (GhCAL), an AGAMOUS family gene, during flower bud formation and the resulting two proteins form a heterodimer. Overexpressing GhAGL8 also increases cotton yield without affecting fiber quality. Thus, the formation of a heterodimer from GhAGL8 and GhCAL promotes transition from vegetative to reproductive growth by repressing the expression of GhTFL1 in cotton. These findings provide molecular targets and candidate genes for breeding early maturing and high yield cotton cultivars.
[学术文献 ] CRISPR/Cas9-mediated GhFT-targeted mutagenesis prolongs indeterminate growth and alters plant architecture in cotton 进入全文
PLANT SCIENCE
The shift from vegetative to reproductive growth is an important developmental transition that affects flowering and maturation, architecture, and ecological adaptability in plants. The florigen-antiflorigen system universally controls flowering and plant architecture, and changes to the ratio of these components alter this transition and disrupt growth. The genes FT (FLOWERING LOCUS T), encoding the florigen protein FT, and CETS [CENTRORADIALIS (CEN)/TERMINAL FLOWER1 (TFL1)/SELF-PRUNING (SP)], encoding antiflorigen proteins, have opposing roles. Upland cotton (Gossypium hirsutum) is one of the world's most widely cultivated cotton varieties, and its complex allotetraploid genome contains only one homoeologous pair of FT genes (GhFT-A and GhFT-D). The functionally conserved gene GhFT promotes flowering and plays a role in plant architecture, although the molecular regulation of flowering and plant architecture in cotton remains unclear. In this study, CRISPR/Cas9 technology was used to induce mutations in the first and second exons of GhFT, respectively. G. hirsutum cv. YZ-1 was transformed with a CRISPR/Cas9-GhFT vector using Agrobacterium tumefaciens, and a diverse set of mutations was identified at the editing site. Compared with the wild type, mutant plants could not transition between vegetative and reproductive growth, and significant alterations to plant architecture were observed. Quantitative RT-PCR revealed downregulation of the homologous floral meristem identity genes APETALA1 (GhAP1) and OVEREXPRESSION OF CONSTANS 1 (GhSOC1) and upregulation of the TFL1 homologs GhTFL1-1 and GhTFL1-2. These results suggested that GhFT played a significant role in flowering time and plant architecture and that the ratio of florigen-antiflorigen components was critical to producing improved cotton varieties. This study provided a basis for future investigations of molecular breeding in cotton and guidance for the agricultural production of this crop.
