Rice (Oryza sativa L.) is a globally important food crop, yet potassium (K⁺) deficiency severely impairs its growth and productivity. γ-Aminobutyric acid (GABA), a non-protein amino acid, regulates plant growth and abiotic stress tolerance; however, its involvement in rice responses to K⁺ limitation remains unexplored. In this study, we investigated how endogenous GABA modulates rice adaptation to K⁺ deficiency using wild-type Nipponbare (WT), GABA-overproducing lines (gad3-ox1 and gad3-ox2), and a GABA-deficient mutant (gad1/3-ko). Under low- K⁺ and K⁺-deficient conditions, gad3-ox1 and gad3-ox2 lines exhibited superior growth performance, higher root activity, enhanced photosynthetic capacity and increased activities of the antioxidant enzymes superoxide dismutase (SOD) and peroxidase (POD) compared with WT, whereas gad1/3-ko displayed impaired growth and heightened stress sensitivity. The GABA-overproducing lines also accumulated higher levels of GABA and proline but lower levels of reactive oxygen species (O₂·⁻ and H₂O₂), malondialdehyde (MDA), and relative electrical conductivity, indicating reduced oxidative damage. These results suggest that elevated endogenous GABA improves rice tolerance to K⁺ limitation by enhancing root activity, maintaining photosynthetic capacity, and strengthening antioxidant defense. This study provides valuable insights into the physiological role of GABA in nutrient stress adaptation and offers a theoretical basis for utilizing GABA to improve rice resilience under K⁺ -limited conditions.

Anthocyanins and terpenoids are secondary metabolites with well-documented health benefits. Isopentenyl transferases (IPTs) are key enzymes in cytokinin (CK) biosynthesis. While ADP/ATP-type IPTs and their associated trans-zeatin (tZ)-CKs and iP-CKs are considered to play regulatory roles in growth and development, as well as stress acclimation in plants, tRNA-type IPTs and cis-zeatin CKs (cZ-CKs), which may serve housekeeping functions, remain less studied. In this study, the tRNA-type IPT gene FveIPT2 was overexpressed in woodland strawberries (Fragaria vesca). Overexpression had minimal impact on plant growth and CK levels but resulted in transgenic fruits exhibiting a significant increase in total phenolic, flavonoid, and anthocyanin contents, indicating enhanced fruit quality. Metabolite profiling revealed substantial increases in nine specific anthocyanins and 24 out of 47 detected terpenoids in the transgenic fruits. Real-time quantitative polymerase chain reaction (RT-qPCR) analysis confirmed the upregulation of genes involved in anthocyanin and terpenoid biosynthesis and transport. These findings demonstrate that while tRNA-type IPTs may primarily play housekeeping roles, FveIPT2 overexpression can significantly enhance fruit quality by boosting terpenoid and anthocyanin accumulation, highlighting the unexpected potential of these genes to improve the nutritional value of edible fruits.

Reducing endogenous CK levels accelerates fruit ripening in tomato by regulating ethylene biosynthesis and signalling pathway. Tomato is a typical climacteric fruit and is recognized as one of the most important horticultural crops globally. The ripening of tomato fruits is a complex process, highly regulated by phytohormones. Cytokinin (CK) is a hormone that primarily impacts the early development of fruit, however its influence on fruit ripening has not been thoroughly investigated. In this study, we used both wild-type Micro-Tom and transgenic tomato plants that overexpress AtCKX2, a CK degradation gene driven by the fruit-specific promoter Tfm7, to investigate the effect of CK on tomato fruit ripening. Our findings revealed that reducing endogenous CK levels in transgenic plants can accelerate the ripening process of tomato fruits. Premature activation of ethylene biosynthetic genes and ripening regulator genes was upregulated in CK-deficient fruits. Moreover, the application of exogenous ethylene inhibitors resulted in delayed fruit ripening in CK-deficient fruits. These results together suggest that CK plays a negative role in tomato fruit ripening by affecting the ethylene pathway.

Although cytokinins (CKs) regulate fruit development, no direct genetic evidence supports the role of endogenous CKs in pericarp growth or development or fruit size. Here, we report that the reduction in levels of endogenous active CKs via overexpression of the CK-inactivating enzyme gene AtCKX2 specifically in fruit tissues resulted in reduced pericarp thickness and smaller fruit size compared with wild-type control fruits. Pericarp thickness and single fruit weight in transgenic plants were significantly reduced. Analysis of paraffin sections showed that the reduced pericarp thickness was due largely to a decreased number of cells, and thus decreased cell division. Transcriptome profiling showed that the expression of cell division- and expansion-related genes was reduced in AtCKX2-overexpressing fruits. In addition, the expression of auxin-signaling and gibberellin-biosynthetic genes was repressed, whereas that of gibberellin-inactivating genes was enhanced, in AtCKX2-overexpressing fruits. These results demonstrate that endogenous CKs regulate pericarp cell division and subsequently fruit size. They also suggest that CKs interact with auxin and gibberellins in regulating tomato pericarp thickness and fruit size.

弓形虫是一种复杂的单细胞原生动物寄生虫,通过入侵宿主细胞、分裂和诱导宿主细胞破裂等一系列的过程,在温血动物体内进行增殖.弓形虫的生物学特征受基因组、表观遗传及转录等多种因素的调控.蛋白质翻译后修饰(protein post-translational modifications,PTMs),如磷酸化、泛素化、巴豆酰化、棕榈酰化、琥珀酰化、乙酰化、甲基化、糖基化和二羟基异丁酰化等,是弓形虫调节对细胞外刺激的反应和生命周期转变的主要机制之一.弓形虫蛋白质翻译后修饰通过改变靶蛋白的定位、结构、活性、蛋白质-蛋白质相互作用等增加蛋白质的复杂性和多样性,从而在虫体生命周期的任何时间点都可以发挥至关重要的作用.在这篇综述中,作者重点对弓形虫蛋白质翻译后修饰进行简要总结,以期为深入研究弓形虫的生物学特征奠定基础.

弓形虫几乎可入侵一切温血脊椎动物的有核细胞,造成较为严重的人兽共患弓形虫病,威胁人类和动物的健康.与其他病原菌入侵宿主的方式有所不同,弓形虫以一种独特的运动方式入侵宿主细胞,其中滑行运动是弓形虫成功入侵宿主细胞的关键环节.弓形虫入侵宿主是一个连续且复杂的过程,在入侵的过程中,虫体可分泌一系列蛋白质分子,以介导虫体在宿主细胞中滑行、黏附与入侵等重要功能.研究弓形虫入侵宿主细胞的详细过程,可进一步揭示介导或参与虫体入侵宿主细胞的重要蛋白质分子的作用及其机制,为弓形虫疾病的预防与治疗药物的研发提供参考.

顶复合体是顶复门原虫特有的结构,由分泌型细胞器和细胞骨架元素件构成,其显著特征是具有一个由微管蛋白纤维组成的类锥体.弓形虫由于具备相对完整的类锥体,为剖析类锥体结构、组成和功能提供了一个成功模型.类锥体的稳定性和相关活动与弓形虫滑行运动、微线体蛋白分泌等生理过程密切相关,对弓形虫入侵宿主细胞至关重要.本文针对类锥体的结构稳定性、相关的蛋白功能以及调控机制展开综述.

为更好地防治棉花黄萎病,在冀棉11根系中分离得到一株对大丽轮枝菌抗性明显的内生细菌,经分子鉴定为解淀粉芽孢杆菌489-2-2.本试验以489-2-2为材料,研究该菌株对棉花黄萎病的防效和机理.结果表明,解淀粉芽孢杆菌489-2-2能够抑制黄萎病菌Vd080的生长,可导致Vd080菌丝形态异常.用该菌株发酵液浸泡棉花种子,对棉花黄萎病的防效为54.99％,灌根法的防效为60.31％.解淀粉芽孢杆菌489-2-2能使植株产生防御酶,诱导的免疫反应较强,且该菌株能定殖到棉花幼苗根系内部.本研究结果为解淀粉芽孢杆菌489-2-2的利用提供了理论依据.

实时荧光定量PCR作为研究基因表达的重要手段,在操作过程中需要内参基因作校正与标准化.本文以绿豆(Vigna radiata)野生型'苏绿1号'(苏绿)及其突变体08 (08)为材料,采用实时荧光定量PCR技术分析6个候选内参基因(EF1α、TUA、TUB、CHS、GADPH、Actin)在不同品种、不同部位(根、茎、叶)及镉诱导前后的表达趋势,继而利用geNorm、NormFinder和BestKeeper这三款软件对候选内参基因的表达稳定性进行综合分析,最后利用目的 基因Nramp5进行验证.实验结果表明,Actin与TUA是所有样品中表达最稳定的内参基因,CHS表达稳定性最差.本研究为将来绿豆基因表达分析的相关研究提供了参考.

γ-Aminobutyric acid (GABA) is a widely distributed non-protein amino acid mediated the regulation of nitrate uptake and Al3+ tolerance in plants. However, there are few reports about the involvement of GABA in the regulation of iron (Fe) acquisition and translocation. Here, we show that GABA regulates Fe homeostasis in rice seedlings. Exogenous GABA decreased the chlorophyll concentration in leaves, with or without Fe supply. Over-expression of glutamate decarboxylase (GAD) gene, coding a crucial enzyme of GABA production, elevated endogenous GABA content and caused more leaf chlorosis than wild type (Nipponbare). GABA inhibited Fe transportation from roots to shoots and GABA application elevated the expression levels of Fe deficiency (FD)-related genes under conditions of Fe-sufficiency (FS), suggesting that GABA is a regulator of Fe translocation. Using Perls’ blue staining, we found that more ferric iron (Fe3+) was deposited in the epidermal cells of roots treated with GABA compared with control roots. Anatomic section analysis showed that GABA treatment induced more aerenchyma formation compared with the control. Aerenchyma facilitated the oxidization of soluble ferrous iron (Fe2+) into insoluble Fe3+, resulted in Fe precipitation in the epidermis, and inhibited the transportation of Fe from roots to shoots.

To explore the possible mechanism of high rates of ammonium nitrate(NH4NO3)in the regula-tion of root hair formation,we grew wild type(WT),auxin-insensitive and ethylene-insensitive mutant seedlings on vertically oriented agar plates.Our study found that:(1)high rates of ammonium nitrate (NH4NO3)supply stimulated the branched root hair formation and inhibited root hair elongation.(2)The effect of NH4NO3on root hair formation were blocked by reactive oxygen species(ROS)and diphenylene iodonium chloride(DPI),suggesting that ROS was involved in NH4NO3-induced branched root hair for-mation.(3)The treatment of auxin or ethylene under high NH4NO3condition completely inhibited high NH4NO3-induced branched root hair formation.(4)Either eir1-3 seedlings treated with auxin or aux1-7 and axr1-3 treated with ACC,the NH4NO3-induced branched root hair formation was inhibited.The re-sults above showed that ROS,auxin and ethylene involved in high NH4NO3-induced branched root hair formation.Auxin played a compensating role in the absence of an ethylene response and ethylene played a supplemental role in the absence of an auxin response.A higher level of auxin was required for preventing branched root hair formation in the absence of ethylene signaling.

[Objectives]The aim of the paper is to explore the possible mechanism of triacontanol(TRIA)in the regulation of lateral root(LR)development,and to provide theoretical basis for the practice. [Methods]Using wild type(WT),auxin-insensitive mutant seedlings as materials,the 5-day-old seedlings were treated with different concentrations of TRIA and the effect of TRIA on LR formation was analyzed. [Results]TRIA treatment induced LR formation markedly,and the increase in the LR density was positively correlated with TRIA concentration. After treatment with 0.20,0.50,and 1.00 μmol·L-1TRIA for 8 d,the density of LR increased by 59.0%,97.9% and 54.2%,respectively. The density of stage A lateral root primordium increased by 67.8% under 0.5 μmol·L-1 TRIA treatment compared with the control. TRIA application significantly increased the indole-3-acetic acid(IAA)level,transcript levels of many IAA biosynthesis genes and the expression levels of DR5:GUS and IAA2:GUS in root. Auxin transport inhibitors 2,3, 5-triiodobenzoic acid(TIBA)and 1-naphthylphthalamic acid(NPA),and the auxin action inhibitor p-chlorophenoxy isobutyric acid (PCIB)each inhibited TRIA-mediated LR formation dramatically in WT seedlings. Further genetic studies revealed that LR formation in tir1-1 and axr1-3 mutants was insensitive to TRIA treatment,but LR formation was less sensitive in aux1-7 and eir1-1 mutants than in WT plants. [Conclusions]Our results showed that TRIA treatment promoted LR formation by inducing de novo formation of lateral root primordium(LRP)in Arabidopsis seedlings and auxin-dependent pathway participated in the regulation of LR formation when Arabidopsis seedlings were subjected to exogenous TRIA application.

Salt stress is a main abiotic stress that limits agricultural productivity in many parts of the world. To investigate whether poly-γ-glutamic acid (γ-PGA) can alleviate the negative effects of salt stress on wheat, a foliar application of 400 mg/L γ-PGA was applied to wheat seedlings, which were then subjected to 150 mM NaCl. Our results showed that after application of γ-PGA, the plant height, the plant weight, and the antioxidant enzymes including superoxide dismutase, peroxidase, and catalase were significantly increased compared with the treatment of 150 mM NaCl alone. Meanwhile, γ-PGA application also resulted in high accumulation of K+ and decreased storage of Na+ in wheat leaves. These results suggest that γ-PGA treatment may improve salt tolerance of wheat by diminishing ionic imbalances and enhancing antioxidant capacity. Our results indicate that exogenous γ-PGA could alleviate the damage caused by salt stress.

Excessive use of nitrogen (N) fertilizer has increased ammonium (NH4+ ) accumulation in many paddy soils to levels that reduce rice vegetative biomass and yield. Based on studies of NH4+ toxicity in rice (Oryza sativa, Nanjing 44) seedlings cultured in agar medium, we found that NH4+ concentrations above 0.75 mM inhibited the growth of rice and caused NH4+ accumulation in both shoots and roots. Use of excessive NH4+ also induced rhizosphere acidification and inhibited the absorption of K, Ca, Mg, Fe and Zn in rice seedlings. Under excessive NH4+ conditions, exogenous γ-aminobutyric acid (GABA) treatment limited NH4+ accumulation in rice seedlings, reduced NH4+ toxicity symptoms and promoted plant growth. GABA addition also reduced rhizosphere acidification and alleviated the inhibition of Ca, Mg, Fe and Zn absorption caused by excessive NH4+ . Furthermore, we found that the activity of glutamine synthetase/NADH-glutamate synthase (GS; EC 6.3.1.2/NADH-GOGAT; EC1.4.1.14) in root increased gradually as the NH4+ concentration increased. However, when the concentration of NH4+ is more than 3 mM, GABA treatment inhibited NH4+ -induced increases in GS/NADH-GOGAT activity. The inhibition of ammonium assimilation may restore the elongation of seminal rice roots repressed by high NH4+ . These results suggest that mitigation of ammonium accumulation and assimilation is essential for GABA-dependent alleviation of ammonium toxicity in rice seedlings.

Changes in growth and distribution of inorganic mineral elements and organic active substances in seedlings of A. vera were examined under treatments of 0.44 and 0.88 MPa polyethylene glycol 6000 (PEG) and corresponding isosmotic sodium chloride (NaCl). All stress treatments inhibited plant growth, with NaCl severely inhibiting the growth of the seedlings than PEG. However, leaf biomass did not change significantly. The nitrogen concentration under PEG was maintained higher than that under NaCl. Salinity caused more severe ionic imbalance than dehydration. However, when the concentration of NaCl was increased, ion homeostasis was maintained. Stressors induced an increase in aloin concentration in leaves, especially in young leaves. Polysaccharide concentrations in leaves did not change under dehydration. However, the polysaccharide concentration decreased in the middle and base leaves under NaCl. A. vera exhibited high adaptability to suitable osmotic stress, which increases its main active ingredients in leaves.

Root hairs are plastic in response to nutrient supply, but relatively little is known about their development under low ammonium (NH4(+)) conditions. This study showed that reducing NH4(+) for 3 days in wild-type Arabidopsis seedlings resulted in drastic elongation of root hairs. To investigate the possible mediation of ethylene and auxin in this process, seedlings were treated with 2,3,5-triiodobenzoic acid (TIBA, auxin transport inhibitor), 1-naphthylphthalamic acid (NPA, auxin transport inhibitor), p-chlorophenoxy isobutyric acid (PCIB, auxin action inhibitor), aminoethoxyvinylglycine (AVG, chemical inhibitor of ethylene biosynthesis), or silver ions (Ag(+), ethylene perception antagonist) under low NH4(+) conditions. Our results showed that TIBA, NPA and PCIB did not inhibit root hair elongation under low NH4(+) conditions, while AVG and Ag(+) completely inhibited low NH4(+)-induced root hair elongation. This suggested that low NH4(+)-induced root hair elongation was dependent on the ethylene pathway, but not the auxin pathway. Further genetic studies revealed that root hair elongation in auxin-insensitive mutants was sensitive to low NH4(+) treatment, but elongation was less sensitive in ethylene-insensitive mutants than wild-type plants. In addition, low NH4(+)-induced root hair elongation was accompanied by reactive oxygen species (ROS) accumulation. Diphenylene iodonium (DPI, NADPH oxidase inhibitor) and dimethylthiourea (DMTU, ROS scavenger) inhibited low NH4(+)-induced root hair elongation, suggesting that ROS were involved in this process. Moreover, ethylene acted together with ROS to modulate root hair elongation under low NH4(+) conditions. These results demonstrate that a signaling pathway involving ethylene and ROS participates in regulation of root hair elongation when Arabidopsis seedlings are subjected to low NH4(+) conditions.

Key message Our results show that methyl jasmonate induces plasma membrane H+-ATPase activity and subsequently influences the apoplastic pH of trichoblasts to maintain a cell wall pH environment appropriate for root hair development.Abstract Root hairs, which arise from root epidermal cells, are tubular structures that increase the efficiency of water absorption and nutrient uptake. Plant hormones are critical regulators of root hair development. In this study, we investigated the regulatory role of the plasma membrane (PM) H+-ATPase in methyl jasmonate (MeJA)-induced root hair formation. We found that MeJA had a pronounced effect on the promotion of root hair formation in lettuce seedlings, but that this effect was blocked by the PM H+-ATPase inhibitor vanadate. Furthermore, MeJA treatment increased PM H+-ATPase activity in parallel with H+ efflux from the root tips of lettuce seedlings and rhizosphere acidification. Our results also showed that MeJA-induced root hair formation was accompanied by hydrogen peroxide accumulation. The apoplastic acidification acted in concert with reactive oxygen species to modulate root hair formation. Our results suggest that the effect of MeJA on root hair formation is mediated by modulation of PM H+-ATPase activity.

Lamina joint inclination or leaf angle (the angle between the leaf blade and vertical culm) is a major trait of rice plant architecture. The plant hormone brassinosteroid (BR) is the main regulator of this trait, while other plant hormones, including ethylene, gibberellin, and auxin, also influence leaf angle. In this study, we found that methyl jasmonate (MeJA) also participates in regulating lamina joint inclination. MeJA decreased lamina joint inclination and inhibited the BR-induced increase in lamina joint inclination. Furthermore, addition of a BR synthesis inhibitor increased the extent of change in lamina joint inclination in response to treatment with a low concentration of MeJA (0.05 or 0.5mgL−1), but it did not alter the lamina joint inclination of plants treated with a high concentration of MeJA (5mgL−1). Further studies showed that MeJA treatment significantly repressed the expression of BR biosynthesis-related genes and decreased endogenous BRs levels. In addition, the lamina joint inclination in the OsBRI1 mutant d61-1 was less sensitive to MeJA compared with its wild type counterpart, and lithium chloride-induced inactivation of GSK3-like kinase, a negative regulator of BR signaling, partly rescued the MeJA-induced reduction in lamina joint inclination. Further studies showed that MeJA treatment reduced the mRNA levels of BR signaling and target genes. These results indicate that MeJA-inhibition of lamina joint inclination may depend on BR biosynthesis and the BR signaling pathway.

With increasing demand for irrigation water, agricultural scientists and planners pay more attention to the utilization of diluted seawater as an alternative source for irrigation of crops. A greenhouse pot experiment was conducted to study how seawater stress (SS) affects growth, water content, cationic accumulation, and active ingredients in leaves of Aloe vera after 30 d of growth in nutrient media with 0% (control), 22% (22% SS), and 42% (42% SS) seawater stress. Results indicated the SS did not change dry biomass of leaves and stems, but gradually decreased biomass allocation to roots with increasing seawater stress. Na+ and Cl− in A. vera plant did not increase obviously with a big increase in seawater percentage due to low transpiration of Aloe vera. 42% SS decreased N concentration in most plant organs, but did not change or increased P concentration. Seawater stress tended to decrease concentrations of K+ and Ca2+ in A. vera. However, seawater salinity tended to increase the concentrations of aloin concentration in top (young) and middle leaves, and there was no significant effect of both stresses on aloin concentration in base (old) leaves. The 42% SS treatment decreased polysaccharide concentrations only in the base leaves, but not in top and middle leaves. In summary, supplying suitably diluted seawater for 30 d could increase the qualities and value of A. vera, without substantial effects on shoot dry biomass production.