Planta最新文献

Plants produce secondary metabolites that serve various functions, including defense against biotic and abiotic stimuli. Many of these secondary metabolites possess valuable applications in diverse fields, including medicine, cosmetic, agriculture, and food and beverage industries, exhibiting their importance in both plant biology and various human needs. Small RNAs (sRNA), such as microRNA (miRNA) and small interfering RNA (siRNA), have been shown to play significant roles in regulating the metabolic pathways post-transcriptionally by targeting specific key genes and transcription factors, thus offering a promising tool for enhancing plant secondary metabolite biosynthesis. In this review, we summarize current approaches for manipulating sRNAs to regulate secondary metabolite biosynthesis in plants. We provide an overview of the latest research strategies for sRNA manipulation across diverse plant species, including the identification of potential sRNAs involved in secondary metabolite biosynthesis in non-model plants. We also highlight the potential future research directions, focusing on the manipulation of sRNAs to produce high-value compounds with applications in pharmaceuticals, nutraceuticals, agriculture, cosmetics, and other industries. By exploring these advanced techniques, we aim to unlock new potentials for biotechnological applications, contributing to the production of high-value plant-derived products.

Main conclusion

The high intrinsic water-use efficiency of Erianthus may be due to the low abaxial stomatal density and the accumulation of leaf metabolites such as betaine and gamma-aminobutyric acid.

Abstract

Sugarcane is an important crop that is widely cultivated in tropical and subtropical regions of the world. Because drought is among the main impediments limiting sugarcane production in these regions, breeding of drought-tolerant sugarcane varieties is important for sustainable production. Erianthus arundinaceus, a species closely related to sugarcane, exhibits high intrinsic water-use efficiency (iWUE), the underlying mechanisms for which remain unknown. To improve the genetic base for conferring drought tolerance in sugarcane, in the present study, we performed a comprehensive comparative analysis of leaf gas exchange and metabolites in different organs of sugarcane and Erianthus under wet and dry soil-moisture conditions. Erianthus exhibited lower stomatal conductance under both conditions, which resulted in a higher iWUE than in sugarcane. Organ-specific metabolites showed gradations between continuous parts and organs, suggesting linkages between them. Cluster analysis of organ-specific metabolites revealed the effects of the species and treatments in the leaves. Principal component analysis of leaf metabolites confirmed a rough ordering of the factors affecting their accumulations. Compared to sugarcane leaf, Erianthus leaf accumulated more raffinose, betaine, glutamine, gamma-aminobutyric acid, and S-adenosylmethionine, which function as osmolytes and stress-response compounds, under both the conditions. Our extensive analyses reveal that the high iWUE of Erianthus may be due to the specific accumulation of such metabolites in the leaves, in addition to the low stomatal density on the abaxial side of leaves. The identification of drought-tolerance traits of Erianthus will benefit the generation of sugarcane varieties capable of withstanding drought stress.

Graphical abstract

Main conclusion

Genetic ablation of the female gametophyte provides direct evidence for the existence of interregional communication during Arabidopsis ovule development and the importance of the female gametophyte in nucellar-tip degeneration.

The angiosperm ovule consists of three regions: the female gametophyte, the nucellus, and the integuments, all of which develop synchronously and coordinately. Previously, interregional communication enabling cooperative ovule development had been proposed; however, the evidence for these communications mostly relies on the analysis of mutant phenotypes. To provide direct evidence, we specifically ablated the Arabidopsis female gametophyte by expressing the diphtheria toxin fragment A (DTA) under the female gametophyte-specific DD13 promoter and analyzed its effects on the development of the nucellus and the integuments. We found that the female gametophyte is not required for integument development or for the orientation and curvature of the ovule body, but is necessary for nucellar-tip degeneration. The results presented here provide direct evidence for communication from the female gametophyte to the nucellus and demonstrate that Arabidopsis ovules require interregional communication for cooperative development.

Main conclusion: The review offers insights into the current state of research on insect pest-resistant GM crops and the regulations governing the cultivation of GM crops in India. India has a rich crop diversity of more than 160 major and minor crops through its diverse agroclimatic conditions. Insect pests alone cause around USD 36 billion in crop loss annually in India. The last two decades witnessed considerable progress in managing insect pests by adopting innovative techniques including transgenics. In research, significant advancement has been brought in insect pest-resistant transgenics in India since its inception in 2002. However, any events have not been endorsed owing to biosafety impediments, except Bt cotton reaching the commercial release stage. A landmark decision to exempt certain types of gene-edited plants from genetically modified organism (GMO) regulations offers great promise for developing novel insect-resistant crops in India. The article reviews the current research on insect pest-resistant transgenics and its regulations in India.

Main conclusion: Biofortification of legumes using diverse techniques such as plant breeding, agronomic practices, genetic modification, and nano-technological approaches presents a sustainable strategy to address micronutrient deficiencies of underprivileged populations. The widespread issue of chronic malnutrition, commonly referred to as "hidden hunger," arises from the consumption of poor-quality food, leading to various health and cognitive impairments. Biofortified food crops have been a sustainable solution to address micronutrient deficiencies. This review highlights multiple biofortification techniques, such as plant breeding, agronomic practices, genetic modification, and nano-technological approaches, aimed at enhancing the nutrient content of commonly consumed crops. Emphasizing the biofortification of legumes, this review employs bibliometric analysis to examine research trends from 2000 to 2023. It identifies key authors, influential journals, contributing countries, publication trends, and prevalent keywords in this field. The review highlights the progress in developing biofortified crops and their potential to improve global nutrition and help underprivileged populations.

Main conclusion: The PcHsp70-5 enhances drought stress tolerance in transgenic Arabidopsis thaliana by upregulating stress tolerance genes and antioxidant enzyme activities. Heat shock proteins (HSPs) constitute a class of evolutionarily conserved proteins synthesized by organisms in response to various adverse environmental stimuli such as elevated temperatures, drought, hormonal fluctuations, high salt concentrations, and mechanical stress. However, research on HSPs has predominantly focused on model plants and crops, whereas their functions in desert plants have not been well investigated. This study analyzed the transcriptome of Pugionium cornutum and identified the complete ORFs of 25 genes of the PcHsp70 family genes. Their expression levels under drought stress were investigated using existing RNA-seq data. PcHsp70-5 genes exhibited high expression levels in both roots and leaves under drought stress. Consequently, the PcHsp70-5 genes were cloned and transformed into Arabidopsis thaliana for further analysis of their roles in drought stress response. Real-time fluorescence quantitative PCR (qRT-PCR) analysis demonstrated that both, drought stress and ABA, induced PcHsp70-5 expression. Under drought conditions, transgenic Arabidopsis plants exhibited markedly enhanced growth compared to wild-type plants, as evidenced by improved survival rates, root length, fresh weight, chlorophyll content, and reduced levels of malondialdehyde (MDA) and hydrogen peroxide (H₂O₂) in leaves, indicating that PcHsp70-5 overexpression mitigated growth inhibition and oxidative damage induced by drought stress. Subsequent research revealed that PcHsp70-5 overexpression significantly augmented the activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and increased the proline content in transgenic Arabidopsis under drought conditions, alongside a significant increase in the expression levels of genes related to stress tolerance. This suggests that PcHsp70-5 enhances drought stress tolerance in transgenic Arabidopsis by upregulating stress tolerance genes and antioxidant enzyme activities.

Main conclusion: Allotetraploid wheat reflects evolutionary divergence and domestication convergence in the karyotypic and phenotypic evolution, accompanied with the transformation from r- strategy to K- strategy in reproductive fitness. Allotetraploid wheat, the progenitor of hexaploidy bread wheat, has undergone 300,000 years of natural evolution and 10,000 years of domestication. The variations in karyotype and phenotype as well as fertility fitness have not been systematically linked. Here, by combining fluorescent in situ hybridization with the quantification of phenotypic and reproductive traits, we compared the karyotype, vegetative growth phenotype and reproductive fitness among synthesized, wild and domesticated accessions of allotetraploid wheat. We detected that the wild accessions showed dramatically high frequencies of homologous recombination and copy number variations of simple sequence repeats (SSR) comparing with synthetic and domesticated accessions. The phenotypic traits reflected significant differences among the populations shaped by distinct evolutionary processes. The diversity observed in wild accessions was significantly greater than that in domesticated ones, particularly in traits associated with vegetative growth and spike morphology. We found that the active pollen of domesticated accessions exhibited greater potential of germination, despite a lower rate of active pollen compared with the wild accessions, indicating a transformation in reproductive fitness strategy for pollen development in domesticated accessions compared to the wild accessions, from r-strategy to K-strategy. Our results demonstrate the condensation of karyotype and phenotype from natural wild accessions to domesticated accessions in allotetraploid wheats. Ecological strategy transformation should be seriously considered from evolution to domestication in polyploid plants, especially crops, which may provide a perspective on the adaptive evolution of polyploid plants.

Main conclusion: This review comprehensively elucidates maize drought tolerance mechanisms, vital for global food security. It highlights genetic networks, key genes, CRISPR-Cas applications, and physiological responses, guiding resilient variety development. Maize, a globally significant crop, confronts the pervasive challenge of drought stress, impacting its growth and yield significantly. Drought, an important abiotic stress, triggers a spectrum of alterations encompassing maize's morphological, biochemical, and physiological dimensions. Unraveling and understanding these mechanisms assumes paramount importance for ensuring global food security. Approaches like developing drought-tolerant varieties and harnessing genomic and molecular applications emerge as effective measures to mitigate the negative effects of drought. The multifaceted nature of drought tolerance in maize has been unfolded through complex genetic networks. Additionally, quantitative trait loci mapping and genome-wide association studies pinpoint key genes associated with drought tolerance, influencing morphophysiological traits and yield. Furthermore, transcription factors like ZmHsf28, ZmNAC20, and ZmNF-YA1 play pivotal roles in drought response through hormone signaling, stomatal regulation, and gene expression. Genes, such as ZmSAG39, ZmRAFS, and ZmBSK1, have been reported to be pivotal in enhancing drought tolerance through diverse mechanisms. Integration of CRISPR-Cas9 technology, targeting genes like gl2 and ZmHDT103, emerges as crucial for precise genetic enhancement, highlighting its role in safeguarding global food security amid pervasive drought challenges. Thus, decoding the genetic and molecular underpinnings of drought tolerance in maize sheds light on its resilience and paves the way for cultivating robust and climate-smart varieties, thus safeguarding global food security amid climate challenges. This comprehensive review covers quantitative trait loci mapping, genome-wide association studies, key genes and functions, CRISPR-Cas applications, transcription factors, physiological responses, signaling pathways, offering a nuanced understanding of intricate mechanisms involved in maize drought tolerance.

Main conclusion: Mutation at A¹²⁶ in lycopene-β-cyclase of Crocus (CstLcyB2a) sterically hinders its binding of δ-carotene without affecting lycopene binding, thereby diverting metabolic flux towards β-carotene and apocarotenoid biosynthesis. Crocus sativus, commonly known as saffron, has emerged as an important crop for research because of its ability to synthesize unique apocarotenoids such as crocin, picrocrocin and safranal. Metabolic engineering of the carotenoid pathway can prove a beneficial strategy for enhancing the quality of saffron and making it resilient to changing climatic conditions. Here, we demonstrate that introducing a novel mutation at A¹²⁶ in stigma-specific lycopene-β-cyclase of Crocus (CstLcyB2a) sterically hinders its binding of δ-carotene, but does not affect lycopene binding, thereby diverting metabolic flux towards β-carotene formation. Thus, A126L-CstLcyB2a expression in lycopene-accumulating bacterial strains resulted in enhanced production of β-carotene. Transient expression of A126L-CstLcyB2a in C. sativus stigmas enhanced biosynthesis of crocin. Its stable expression in Nicotiana tabacum enhanced β-branch carotenoids and phyto-hormones such as abscisic acid (ABA) and gibberellic acids (GA's). N. tabacum transgenic lines showed better growth performance and photosynthetic parameters including maximum quantum efficiency (Fv/Fm) and light-saturated capacity of linear electron transport. Exogenous application of hormones and their inhibitors demonstrated that a higher ratio of GA₄/ABA has positive effects on biomass of wild-type and transgenic plants. Thus, these findings provide a platform for the development of new-generation crops with improved productivity, quality and stress tolerance.