Crop Journal最新文献

Late spring cold (LSC) occurred in the reproductive period of wheat impairs spike and floret differentiation during the reproductive period, when young spikelets are very cold-sensitive. However, under LSC, the responses of wheat spikelets at various positions, leaves, and stems and the interactions between them at physiological levels remain unclear. In the present study, two-year treatments at terminal spikelet stage under two temperatures (2 °C, −2 °C) and durations (1, 2, and 3 days) were imposed in an artificial climate chamber to compare the effects of LSC on grain number and yield in the wheat cultivars Yannong 19 (YN19, cold-tolerant) and Xinmai 26 (XM26, cold-sensitive). The night temperature regimes were designed to reproduce natural temperature variation. LSC delayed plant growth and inhibited spike and floret differentiation, leading to high yield losses in both cultivars. LSC reduced dry matter accumulation (DMA, g) in spikes, stems, and leaves, reducing the DMA ratios of the spike to leaf and spike to stem. Plant cell wall invertase (CWINV) activity increased in upper and basal spikelets in YN19, whereas CWINV increased in middle spikelets in XM26. Under LSC, soluble sugar and glucose were transported and distributed mainly in upper and basal spikelets for glume and rachis development, so that spike development was relatively complete in YN19, whereas the upper and basal spikelets were severely damaged and most of the glumes in middle spikelets were relatively completely developed in XM26, resulting in pollen abortion mainly in upper and basal spikelets. The development of glumes and rachides was influenced and grain number per spike was decreased after LSC, with kernels present mainly in middle spikelets. Overall, reduced total DMA and dry matter partitioning to spikes under LSC results in poor spikelet development, leading to high losses of grain yield.

Potassium (K) is an essential macronutrient for plant growth and development and influences yield and quality of agricultural crops. Maize (Zea mays) is one of the most widely distributed crops worldwide. In China, although maize consumes a large amount of K fertilizer, the K uptake/utilization efficiency (KUE) of maize cultivars is relatively low. Elucidation of KUE mechanisms and development of maize cultivars with higher KUE are needed. Maize KUE is determined by K⁺ uptake, transport, and remobilization, which depend on a variety of K⁺ channels and transporters. We review basic information about K⁺ channels and transporters in maize, their functions and regulation, and the roles of K⁺ in nitrogen transport, sugar transport, and salt tolerance. We discuss challenges and prospects for maize KUE improvement.

Aquaporins play important regulatory roles in improving plant abiotic stress tolerance. To better understand whether the OsPIP1 genes collectively dominate the osmotic regulation in rice under salt stress, a cluster editing of the OsPIP1;1, OsPIP1;2 and OsPIP1;3 genes in rice was performed by CRISPR/Cas9 system. Sequencing showed that two mutants with Cas9-free, line 14 and line 18 were successfully edited. Briefly, line 14 deleted a single C base in both the OsPIP1;1 and OsPIP1;3 genes, and inserted a single T base in the OsPIP1;2 gene, respectively. While line 18 demonstrated an insertion of a single A base in the OsPIP1;1 gene and a single T base in both the OsPIP1;2 and OsPIP1;3 genes, respectively. Multiplex editing of the OsPIP1 genes significantly inhibited photosynthetic rate and accumulation of compatible metabolites, but increased MDA contents and osmotic potentials in the mutants, thus delaying rice growth under salt stress. Functional loss of the OsPIP1 genes obviously suppressed the expressions of the OsPIP1, OsSOS1, OsCIPK24 and OsCBL4 genes, and increased the influxes of Na⁺ and effluxes of K⁺/H⁺ in the roots, thus accumulating more Na⁺ in rice mutants under salt stress. This study suggests that the OsPIP1 genes are essential modulators collectively contributing to the enhancement of rice salt stress tolerance, and multiplex editing of the OsPIP1 genes provides insight into the osmotic regulation of the PIP genes.

Nitrogen (N) and phosphorus (P) are two essential mineral nutrients for plant growth, which are required in relative high amount in plants. Plants have evolved a series of strategies for coordinately acquiring and utilizing N and P. However, physiological and molecular mechanisms underlying of N and P interactions remain largely unclear in soybean (Glycine max). In this study, interactions of N and P were demonstrated in soybean as reflected by significant increases of phosphate (Pi) concentration in both leaves and roots by N deficiency under Pi sufficient conditions. A total of four nitrogen limitation adaptation (NLA), encoding RING-type E3 ubiquitin ligase were subsequently identified in soybean genome. Among them, transcription of GmNLA1-1 and GmNLA1-3 was decreased in soybean by N starvation under Pi sufficient conditions, not for GmNLA1-2. Suppression of all three GmNLA1 members was able to increase Pi concentration regardless of the P and N availability in the growth medium, but decrease fresh weight under normal conditions in soybean hairy roots. However, comparted to changes in control lines at two N levels, N deficiency only resulted in a relatively higher increase of Pi concentration in GmNLA1-1 or GmNLA1-3 suppression lines, strongly indicating that GmNLA1-1 and GmNLA1-3 might regulate P homeostasis in soybean response to N starvation. Taken together, our result suggest that redundant and diverse functions present in GmNLA1 members for soybean coordinate responses to P and N availability, which mediate P homeostasis.

Plant male reproduction is a fine-tuned developmental process that is susceptible to stressful environments and influences crop grain yields. Phytohormone signaling functions in control of plant normal growth and development as well as in response to external stresses, but the interaction or crosstalk among phytohormone signaling, stress response, and male reproduction in plants remains poorly understood. Cross-species comparison among 514 stress-response transcriptomic libraries revealed that ms33-6038, a genic male sterile mutant deficient in the ZmMs33/ZmGPAT6 gene, displayed an excessive drought stress-like transcriptional reprogramming in anthers triggered mainly by disturbed jasmonic acid (JA) homeostasis. An increased level of JA appeared in ZmMs33-deficient anthers at both meiotic and post-meiotic stages and activated genes involved in JA biosynthesis and signaling as well as genes functioning in JA-mediated drought response. Excessive accumulation of JA elevated expression level of a gene encoding a WRKY transcription factor that activated the ZmMs33 promoter. These findings reveal a feedback loop of ZmMs33-JA-WRKY-ZmMs33 in controlling male sterility and JA-mediated stress response in maize, shedding light on the crosstalk of stress response and male sterility mediated by phytohormone homeostasis and signaling.

Rice is an important dietary source of the toxic mineral cadmium (Cd) for populations in which rice is the main staple food. When grown in agricultural soils that are contaminated with Cd, rice often accumulates excessive Cd into the grains, which is a serious threat to agricultural sustainability and human health. To limit Cd accumulation in rice grains, studies on the genetic basis of Cd accumulation in rice have been carried out extensively, and some low-Cd rice varieties have also been developed in recent years. However, the challenges in low-Cd rice breeding still exist because the outcomes of the current genetic improvements for low-Cd rice cannot fully meet the requirements for the development of Cd-safe rice at present. In this review, we outline the progress in understanding the physiological mechanisms and the genetic nature of Cd accumulation in rice and summarize the strategies and outcomes of low-Cd rice breeding over the past decade. By graphing the physiological mechanism of Cd transport in the rice plant, three key steps and some underlying genes are summarized and discussed. Also, two genetic features of the natural variation in rice grain-Cd accumulation, the phenotypic plasticity and subspecies divergence, and the potential genetic explanations for these features are also discussed. Finally, we summarize and discuss current progress and the potential issues in low-Cd rice breeding using different breeding strategies. We hope to propose strategies for future success in the breeding of low-Cd rice varieties over the next decade.

Alfalfa (Medicago sativa L.) is one of the most extensively grown leguminous forage worldwide. Environmental saline-alkali stress significantly influences the growth, development, and yield of alfalfa, posing a threat to its agricultural production. However, little is known about the potential mechanisms by which alfalfa responds to saline-alkali stress. Here, we investigated these mechanisms by cloning a saline-alkali-induced flavonol synthase gene (MsFLS13) from alfalfa, which was previously reported to be significantly upregulated under saline-alkali stress, and examining its function in the saline-alkali response. Overexpression of MsFLS13 in alfalfa promoted plant tolerance to saline-alkali stress by enhancing flavonol accumulation, antioxidant capacity, osmotic balance, and photosynthetic efficiency. Conversely, MsFLS13 inhibition using RNA interference reduced flavonol synthase activity and inhibited hairy root growth under saline-alkali stress. Yeast one-hybrid and dual-luciferase reporter assays indicated that the R2R3-MYB MsMYB12 transcription factor activates MsFLS13 expression by binding to the MBS motif in the MsFLS13 promoter. Further analysis revealed that abscisic acid mediates the saline-alkali stress response partially by inducing MsMYB12 and MsFLS13 expression, which consequently increases flavonol levels and maintains antioxidant homeostasis in alfalfa. Collectively, our findings highlight the crucial role of MsFLS13 in alfalfa in response to saline-alkali stress and provide a novel genetic resource for creating saline-alkali-resistant alfalfa through genetic engineering.

Silicon (Si) treatment has been shown to reduce the toxicity and accumulation of lead (Pb) in many plants, including rice. The mechanisms responsible for this effect are poorly understood. We investigated the effects of Si treatment on Pb toxicity and accumulation in two rice mutants (lsi1 and lsi2) defective in Si uptake and in their wild types. Si did not alleviate Pb-induced inhibition of root elongation in short-term experiments, but reduced Pb accumulation in wild types, but not in mutants, in long-term experiments. Pre-treatment with Si reduced Pb concentration in xylem sap and Pb accumulation in wild types but not in mutants. In split-root experiments, Si treatment reduced Pb accumulation but did not alter Pb localization in roots. Si treatment suppressed the expression of many genes encoding proteins that may participate in Pb uptake and transport in the wild type, but not in the lsi1 mutant. These results indicate that Si accumulation in shoots is required to reduce Pb uptake in rice and that the effect is achieved via Si-induced suppression of genes encoding proteins involved in Pb uptake and/or transport.

Reliance on agriculture for food security is a constant in all modern societies. Global climate change and population growth have put immense pressure on sustainable agriculture, exacerbating the effects of environmental stresses. Drought is one of the most pressing abiotic stresses that farmers face, presenting an annual threat to crop growth and yield. Crops have evolved extensive morphological, physiological, and molecular mechanisms to combat drought stress. Drought resistance is a polygenic trait, controlled by a complex genetic network and an array of genes working together to ensure plant survival. Many studies have aimed at dissecting the genetic mechanisms underlying drought resistance. Recent studies using linkage and association mapping have made progress in identifying genetic variations that affect drought-resistance traits. These loci may potentially be engineered by genetic transformation and genome editing aimed at developing new, stress-resistant crop cultivars. Here we summarize recent progress in elucidating the genetic basis of crop drought resistance. Molecular-breeding technologies such as marker-assisted selection, genome selection, gene transformation, and genome editing are currently employed to develop drought-resistant germplasm in a variety of crops. Recent advances in basic research and crop biotechnology covered in this review will facilitate delivery of drought-resistant crops with unprecedented efficiency.