Drought stress is a worldwide factor limiting the agricultural production. Silica nanoparticles (SiNPs) could improve plant tolerance to drought stress, but their role in ginger salt response and the mechanisms behind it are still unknown. The effect of SiNP100 on drought-stressed ginger was investigated, and four treatments including CK, SiNP100, drought stress (DS), and DS + SiNP100 were performed at 49 days after sowing. The result showed that drought stress exerts a detrimental impact on ginger growth, photosynthetic performance, and the relative water content of plants. SiNP100 treatment significantly improved photosynthesis (up to 72.7% increase), chlorophyll contents, and relative water content (up to 63% increase), but decreased oxidative damage, which collectively contributed to increased plant growth. Moreover, the application of SiNP100 on drought-stressed ginger has the potential to maintain stomatal opening and increase stomatal density through increasing leaf water potential and maintaining leaf cell integrity. The increased leaf osmotic potential (up to 35.1% increase) and leaf water potential (up to 3.6% increase) may further promote the accumulation of ABA in ginger seedlings. Furthermore, SiNP100 increased root growth and root hydraulic conductance (Lp, up to 3.6% increase), which contribute to the increased root water uptake. Further results revealed that SiNP100 can regulate water balance of ginger plants under drought conditions by up-regulating the expression of ZoAQP genes, especially in the rhizome. Under drought stress, the exogenous application of HgCl2 decreased the water loss transpiration rates of seedlings and SiNP100 alleviated this decrease. Therefore, this study can help to better understand the role of SiNP100 in alleviating drought stress and to further develop technologies for plants to counteract the influence of abiotic stress. Silica nanoparticles improve drought tolerance of ginger seedling.

Silica nanoparticles (SiNPs) offer an ecofriendly and environmentally safe alternative for plant disease management. However, the mechanisms of SiNPs-induced disease resistance are largely unknown. This research evaluated the application of SiNPs in controlling the postharvest decay of ginger rhizomes inoculated with Fusarium solani. In vitro study showed that SiNP had little inhibitory effect on mycelial growth and spore germination of F. solani and did not significantly change mycelium’s MDA content and SDH activity. In vivo analysis indicated that SiNPs decreased the degree of decay around the wounds and decreased the accumulation of H2O2 after long-term pathogenic infection through potentiating the activities of antioxidant enzymes such as SOD, APX, PPO, and CAT. SiNP150 increased the CHI, PAL, and GLU activity at the onset of the experiment. Moreover, SiNP150 treatment increased total phenolics contents by 1.3, 1.5, and 1.2-times after 3, 5, and 7 days of treatment, and increased total flavonoids content throughout the experiment by 9.3%, 62.4%, 26.9%, 12.8%, and 60.8%, respectively. Furthermore, the expression of selected phenylpropanoid pathway-related genes was generally enhanced by SiNPs when subjected to F. solani inoculation. Together, SiNPs can effectively reduce the fungal disease of ginger rhizome through both physical and biochemical defense mechanisms.

[目的]筛选抗枯萎病的生姜品种,建立抗病评价体系,为生姜枯萎病抗病品种选育及抗病机理研究提供理论参考.[方法]选取5个生姜主产区的主栽品种,采用室内人工接种法测定枯萎病菌(腐皮镰刀菌)侵染对不同生姜品种超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)、苯丙氨酸解氨酶(PAL)、几丁质酶(CHI)、β-1,3-葡聚糖苷酶(GLU)活性及次生抗菌物质含量、超氧阴离子(O-2·)、过氧化氢(H2O2)、丙二醛(MDA)含量等的影响,结合抗病系数、主成分分析、聚类分析、相关分析和隶属函数对5个生姜品种幼苗的抗病性进行综合评价.[结果]山东大姜病情指数最低(4.0)、发病率最低(4％)、发病周期最长(24 d),表现出较强的抗病性;罗平小黄姜病情指数最高(45.2)、发病周期最短(7 d),表现抗病性较弱.不同生姜品种幼苗接菌后的生理生化指标均出现不同程度的变化,其中,山东大姜的抗氧化酶(SOD、POD、CAT)活性、防御酶(PAL、CHI、GLU)活性和次生抗菌物质(总酚、类黄酮、木质素)含量均高于其他品种,O-2·、H2O2和MDA含量低于其他品种,而罗平小黄姜呈现相反趋势.主成分分析将12个单项生理生化指标转换为3个独立综合指标,聚类分析将5个生姜品种划分为3类,结合隶属函数综合评价结果,5个生姜品种抗病性强弱表现为:山东大姜>凤头姜>竹根姜>贵州黄姜>罗平小黄姜,与人工接种试验中5个品种的发病程度一致.相关分析结果显示,SOD和类黄酮与抗病性综合评价值(D值)呈极显著正相关(P<0.01).[结论]5个生姜品种中山东大姜抗病性最强,罗平小黄姜抗病性最弱;SOD和类黄酮可作为生姜枯萎病抗性鉴定的主要参考指标.

Gene expression analysis largely improves our understanding of the molecular basis underpinning various plant biological processes. Stable reference genes play a foundational role during the normalization of gene expression levels. However, until now, there have been few reference genes suitable for ginger reverse transcription-quantitative PCR (RT-qPCR) research. In this study, 29 candidate reference genes with stable expression patterns across multiple ginger tissues and 13 commonly used reference genes were selected to design RT-qPCR primers. After amplification specificity validation, 32 candidates were selected and further evaluated by RT-qPCR using samples from various organs subjected to NaCl, drought, heat, waterlogging, and chilling stress. Four strategies, including delta-CT, BestKeeper, geNorm, and NormFinder, were used to rank the stability of reference genes, and the ranks produced by these four strategies were comprehensively evaluated by RefFinder to determine the final rank. Overall, the top three stability reference genes indicated by RefFinder were RBP > ATPase > 40S_S3 . Their expression pattern correlation analysis showed that the coefficients among each pair of RBP , ATPase , and 40S_S3 were larger than 0.96, revealing consistent and stable expression patterns under various treatments. Then, the expression of three pathogenesis-related ( PR ) genes and seven MYB genes in rhizomes during postharvest storage and subjected to pathogen infection was normalized by RBP , ATPase , 40S_S3 , RBP and ATPase , ATPase and 40S-S3 , and RBP and 40S-S3 . The results showed that PR and MYB genes were induced by postharvest deterioration and pathogen infection. The correlation coefficients of RBP / ATPase , RBP / 40S_S3 , ATPase / 40S_S3 , RBP and ATPase/ATPase and 40S-S3 , RBP and ATPase/RBP and 40S-S3 , and ATPase and 40S-S3/RBP and 40S-S3 were 0.99, 0.96, 0.99, 0.99, 1.00, and 1.00, respectively, which confirmed the stability of these three reference genes in postharvest biology studies of ginger. In summary, this study identified appropriate reference genes for RT-qPCR in ginger and facilitated gene expression studies under biotic and abiotic stress conditions.