Research

32 pages, 5093 KiB

Open AccessArticle

Exogenous Proline Alleviated Low Temperature Stress in Maize Embryos by Optimizing Seed Germination, Inner Proline Metabolism, Respiratory Metabolism and a Hormone Regulation Mechanism

by Shiyu Zuo, Jing Li, Wanrong Gu and Shi Wei

Agriculture 2022, 12(4), 548; https://doi.org/10.3390/agriculture12040548 - 12 Apr 2022

Cited by 8 | Viewed by 2422

Abstract

Proline (Pro) is not only an important osmotic adjustment substance, but it also plays an important role in regulating plant abiotic stress resistance. The maize varieties, Xinxin 2 (low temperature insensitive) and Damin 3307 (low temperature sensitive), were chosen as materials, setting a [...] Read more.

Proline (Pro) is not only an important osmotic adjustment substance, but it also plays an important role in regulating plant abiotic stress resistance. The maize varieties, Xinxin 2 (low temperature insensitive) and Damin 3307 (low temperature sensitive), were chosen as materials, setting a normal temperature for germination (22 °C/10 °C, 9d), low temperature germination (4 °C/4 °C, 5d) and normal temperature recovery (22 °C/10 °C, 4d), combined with a proline (15 mmol·L⁻¹) soaking treatment, to reveal the seed germination and regulation mechanism in maize embryos. The results showed that proline significantly improved the germination potential, germination rate, germination index and vigor index of seeds under low temperature stress, increasing the length of the coleoptile and radicle, increasing the dry and fresh weight of young buds (coleoptile + radicle), and increasing the activity of α-amylase. Proline enhanced the activities of Δ1-pyrroline-5-carboxylic acid synthetase (P5CS) and ornithine aminotransferase (OAT) in maize embryos under low temperature stress, enhanced the proline synthesis pathways, and further enhanced proline accumulation. Proline induced the activity of proline dehydrogenase (ProDH) in the early stage of low temperature stress and stress relief. Under low temperature stress, the activities of hexokinase (HXK), phosphofructokinase (PFK), pyruvate kinase (PK), isocitrate dehydrogenase (IDH), succinate dehydrogenase (SDH), malate dehydrogenase (MDH) and glucose-6-phosphate dehydrogenase (G-6-PDH) and glucose-6-phosphate dehydrogenase (G-6-PDH and 6-P-GDH) in maize embryos were decreased, resulting in a decrease in the glycolysis (EMP) pathway, tricarboxylic acid (TCA) cycle and pentose phosphate pathway (PPP). Proline alleviated the inhibition of key enzyme activities of the EMP pathway, TCA cycle and PPP of maize embryos under low temperature stress, increased the activities of cytochrome oxidase (COX) and alternative oxidase (AOX), increased the ATP content, alleviated the inhibition of low temperature stress on main cytochrome pathway activity (ρV_cyt), while further increasing the total respiratory activity (V_t) and the actual operational activity of the alternative pathway (ρV_alt) during seed germination at the initial stage of low temperature stress, as well as improving the inhibition of the V_t and ρV_alt in the middle and late stages of low temperature stress. Under low temperature stress, the content of abscisic acid (ABA) increased significantly, while gibberellin (GA), auxin (IAA) and zeatin nucleoside (ZR) decreased significantly. Proline alleviated the decrease in IAA, ZR and GA contents in maize embryos under low temperature stress, reduced the increase in the ABA content, and reduced the inhibition of low temperature on seed germination. Full article

(This article belongs to the Special Issue Applications of Plant Growth Regulators and Hormones on Crop Resistance)

► Show Figures

Figure 1

16 pages, 3976 KiB

Open AccessArticle

Isolation and Molecular Characterization of Plant-Growth-Promoting Bacteria and Their Effect on Eggplant (Solanum melongena) Growth

by Xuqing Li, Jianli Yan, Dingyi Li, Yugen Jiang, Ya Zhang, Hong Wang, Jingze Zhang, Temoor Ahmed and Bin Li

Agriculture 2021, 11(12), 1258; https://doi.org/10.3390/agriculture11121258 - 12 Dec 2021

Cited by 8 | Viewed by 3025

Abstract

In recent years, the optimum development of land resources has become an important task for ensuring the security of food production in China. Soil microorganisms have been considered to play an important role in conferring soil fertility and productivity. In order to obtain [...] Read more.

In recent years, the optimum development of land resources has become an important task for ensuring the security of food production in China. Soil microorganisms have been considered to play an important role in conferring soil fertility and productivity. In order to obtain the plant-growth-promoting bacteria in newly reclaimed land, a total of 988 bacterial strains were isolated from nine soil samples collected from different sites in wastelands in Hangzhou (Zhejiang Province, China), a rural mountainous area. Among them, five strains exhibited substantial potential of phosphate solubilization, nitrogen fixation, siderophore production and indole acetic acid production at both pH 5.0 and pH 7.0, and also promoted eggplant growth in immature soil from newly reclaimed land. Furthermore, bacterial strains ZJ62 and ZJ3-12 were identified as Pantoeadispersa and Pantoea ananatis, respectively, while strains ZJ5, ZJ9 and ZJ174 were identified as Burkholderiaarboris, Burkholderia pyrrocinia and Burkholderia pyrrocinia, respectively, based on colony morphology observation and phylogenetic analysis of 16S rDNA and the housekeeping genes sequences. Overall, the result of this study showed that the 5 obtained bacterial strains have a great potential in promoting plant growth in immature soil from newly reclaimed land. Full article

(This article belongs to the Special Issue Applications of Plant Growth Regulators and Hormones on Crop Resistance)

► Show Figures

Figure 1

17 pages, 1717 KiB

Open AccessArticle

Glycine Betaine-Mediated Root Priming Improves Water Stress Tolerance in Wheat (Triticum aestivum L.)

by Nazir Ahmed, Mingyuan Zhu, Qiuxia Li, Xilei Wang, Jiachi Wan and Yushi Zhang

Agriculture 2021, 11(11), 1127; https://doi.org/10.3390/agriculture11111127 - 11 Nov 2021

Cited by 7 | Viewed by 2501

Abstract

Droughts represent one of the main challenges that climate change imposes on crop production. As a globally cultivated staple crop, wheat (Triticum aestivum L.) is prone to drought environments. Therefore, improvement in drought tolerance represents a growing concern to ensure food security, [...] Read more.

Droughts represent one of the main challenges that climate change imposes on crop production. As a globally cultivated staple crop, wheat (Triticum aestivum L.) is prone to drought environments. Therefore, improvement in drought tolerance represents a growing concern to ensure food security, especially for wheat. In this perspective, the application of Phyto-phillic exogenous materials such as glycine-betaine (GB) has been attracting attention, particularly in stress-related studies. Since roots procure the water and nutrients for plants, any improvements in their response and capacity against drought stress could induce stress tolerance in plants. However, the knowledge about the changes in root architecture, defense mechanism, hormonal metabolism, and downstream signaling, in response to GB-mediated root priming, is still limited. Therefore, we designed the present study to investigate the role of GB-mediated root priming in improving the water stress tolerance in wheat (cv. Jimai-22) under in-vitro conditions. The roots of twelve days old wheat seedlings were treated with Hoagland’s solution (GB-0), 50 mM GB (GB-1), and 100 mM GB (GB-2) for 48 h and subjected to well-watered (WW) and water-stress (WS) conditions. The osmotic stress substantially impaired shoot/root growth, dry matter accumulation, and increased malondialdehyde (MDA) and hydrogen-peroxide (H₂O₂) production in the roots of wheat seedlings. However, GB-mediated root priming improved the redox homeostasis of wheat roots by boosting the activities of SOD and POD and triggering the significantly higher accumulation of abscisic acid (ABA) and salicylic acid (SA) in the roots of GB-primed plants. Consequently, it modified the root architecture system and improved plant growth, dry matter accumulation, and water-stress tolerance of wheat seedlings. Moreover, GB-mediated root priming increased root sensitivity to water stress and induced overexpression of stress-responsive genes involved in ABA metabolism (TaNECD1, TaABA’OH2), their downstream signal transduction (TaPP2C, TaSNRK2.8), and activation of different transcriptional factors (TabZIP60, TaAREB3, TaWRKY2, TaERF3, and TaMYB3) that are associated with plant metabolite accumulation and detoxification of ROS under water stress conditions. Overall, our results demonstrated that GB-priming improved the physiological and biochemical attributes of wheat plants under WS conditions by improving the drought perception capacity of wheat roots, ultimately enhancing the water stress tolerance. Thus, the GB-priming of roots could help to enhance the water-stress tolerance of economically important crops (i.e., wheat). Full article

(This article belongs to the Special Issue Applications of Plant Growth Regulators and Hormones on Crop Resistance)

► Show Figures

Figure 1

18 pages, 2348 KiB

Open AccessEditor’s ChoiceArticle

Effects of Exogenous Calcium on Adaptive Growth, Photosynthesis, Ion Homeostasis and Phenolics of Gleditsia sinensis Lam. Plants under Salt Stress

by Yun Guo, Yang Liu, Yan Zhang, Jia Liu, Zarmina Gul, Xiao-Rui Guo, Ann Abozeid and Zhong-Hua Tang

Agriculture 2021, 11(10), 978; https://doi.org/10.3390/agriculture11100978 - 09 Oct 2021

Cited by 18 | Viewed by 2813

Abstract

Salinity is the main environmental factor responsible for limited plant growth in many areas of the world. Gleditsia sinensis Lam. is a shelter forest tree species that does not require high-quality soil and can even grow in mild saline soil. This study mainly [...] Read more.

Salinity is the main environmental factor responsible for limited plant growth in many areas of the world. Gleditsia sinensis Lam. is a shelter forest tree species that does not require high-quality soil and can even grow in mild saline soil. This study mainly explored the tolerance of G. sinensis to salt and the effect of exogenous calcium addition on the growth of G. sinensis in a salinized soil. The concentrations of NaCl were set as 0 mmol/L, 100 mmol/L, and 200 mmol/L. Compared with the control, under the NaCl treatment of 200 mmol/L, it was observed that the leaves of G. sinensis turned yellow, the electrical conductivity significantly increased, and the water content and the chlorophyll content significantly decreased, which is probably unfavorable for growth. Our study showed that the addition of 10 mmol/L exogenous calcium chloride under salt stress had a positive effect on the growth and photosynthetic characteristics of G. sinensis. Moreover, the addition of exogenous calcium attenuated the cytotoxicity caused by Na⁺ under salt stress and promoted the equilibrium of ion homeostasis. More importantly, the addition of exogenous calcium ions was beneficial for the survival of G. sinensis plants on salinized land and the increase of effective active ingredient content including phenolic compounds, which is of direct significance for improving environmental problems such as desertification of saline-alkali land. In conclusion, we investigated the effect of salt treatment on G. sinensis, as well as the positive effects of exogenous calcium on the survival and growth of G. sinensis in salt environment, which provided a scientific basis for the targeted cultivation of G. sinensis in salinized land and the effective utilization of salinized and alkaline land. Full article

(This article belongs to the Special Issue Applications of Plant Growth Regulators and Hormones on Crop Resistance)

► Show Figures

Figure 1

15 pages, 2628 KiB

Open AccessArticle

Coronatine Modulated the Generation of Reactive Oxygen Species for Regulating the Water Loss Rate in the Detaching Maize Seedlings

by Haiyue Yu, Yubin Wang, Jiapeng Xing, Yushi Zhang, Liusheng Duan, Mingcai Zhang and Zhaohu Li

Agriculture 2021, 11(7), 685; https://doi.org/10.3390/agriculture11070685 - 20 Jul 2021

Cited by 8 | Viewed by 2375

Abstract

Coronatine (COR), a structural and functional mimic of jasmonates, is involved in a wide array of effects on plant development and defense response. The present study aims to investigate the role of COR, in counteracting drought stress by modulating reactive oxygen species (ROS) [...] Read more.

Coronatine (COR), a structural and functional mimic of jasmonates, is involved in a wide array of effects on plant development and defense response. The present study aims to investigate the role of COR, in counteracting drought stress by modulating reactive oxygen species (ROS) homeostasis, water balance, and antioxidant regulation in detached maize plants. Our results showed that COR can markedly decrease the water loss rate, but the antioxidants diphenyleneiodonium chloride (DPI) and dimethylthiourea (DMTU) eliminate the effect of water loss induced by COR. Using the dye 2′,7′-dichlorofluorescein diacetate (H2DCF-DA) loaded in the maize epidermis guard cells, it is observed that COR could increase ROS production, and then antioxidants DPI and DMTU decreased ROS production induced by COR. In addition, the expression of ZmRBOHs genes, which were associated with ROS generation was increased by COR in levels and ZmRBOHC was highly expressed in the epidermis guard cells. Moreover, COR-treated plants increased H₂O₂ and O₂⁻· accumulation, antioxidant enzyme activities in control plants, while COR relieved the ROS accumulation and antioxidant enzyme activities under PEG treatment. These results indicated that COR could improve maize performance under drought stress by modulating ROS homeostasis to maintain water loss rate and antioxidant enzyme activities. Full article

(This article belongs to the Special Issue Applications of Plant Growth Regulators and Hormones on Crop Resistance)

► Show Figures

Figure 1

14 pages, 2710 KiB

Open AccessArticle

Application of Plant Extracts in Micropropagation and Cryopreservation of Bleeding Heart: An Ornamental-Medicinal Plant Species

by Dariusz Kulus and Natalia Miler

Agriculture 2021, 11(6), 542; https://doi.org/10.3390/agriculture11060542 - 12 Jun 2021

Cited by 8 | Viewed by 3422

Abstract

Lamprocapnos spectabilis (L.) Fukuhara (bleeding heart) is valued both in the horticultural and pharmaceutical markets. Despite its great popularity, information on the in vitro tissue culture technology in this species is limited. There is also little knowledge on the application of plant extracts [...] Read more.

Lamprocapnos spectabilis (L.) Fukuhara (bleeding heart) is valued both in the horticultural and pharmaceutical markets. Despite its great popularity, information on the in vitro tissue culture technology in this species is limited. There is also little knowledge on the application of plant extracts in the tissue culture systems of plants other than orchids. The aim of this study is to compare the utility of traditional plant growth regulators (PGRs) and natural extracts—obtained from the coconut shreds, as well as oat, rice, and sesame seeds—in the micropropagation and cryopreservation of L. spectabilis ‘Gold Heart’ and ‘White Gold’. The biochemical analysis of extracts composition is also included. In the first experiment related to micropropagation via axillary buds activation, the single-node explants were cultured for a 10-week-long propagation cycle in the modified Murashige and Skoog medium fortified either with 1.11 µM benzyladenine (BA) and 1.23 µM indole-3-butritic acid (IBA) or with 10% (v/v) plant extracts. A PGRs- and extract-free control was also considered. In the cryopreservation experiment, the same 10% (v/v) extracts were added into the medium during a seven-day preculture in the encapsulation-vitrification cryopreservation protocol. It was found that the impact of natural additives was cultivar- and trait-specific. In the first experiment, the addition of coconut extract favoured the proliferation of shoots and propagation ratio in bleeding heart ‘Gold Heart’. Rice extract, on the other hand, promoted callus formation in ‘White Gold’ cultivar and was more effective in increasing the propagation ratio in this cultivar than the conventional plant growth regulators (4.1 and 2.6, respectively). Sesame extract suppressed the development of the explants in both cultivars analysed, probably due to the high content of polyphenols. As for the second experiment, the addition of plant extracts into the preculture medium did not increase the survival level of the cryopreserved shoot tips (sesame and oat extracts even decreased this parameter). On the other hand, coconut extract, abundant in simple sugars and endogenous cytokinins, stimulated a more intensive proliferation and growth of shoots after rewarming of samples. Analysing the synergistic effect of conventional plant growth regulators and natural extracts should be considered in future studies related to L. spectabilis. Full article

(This article belongs to the Special Issue Applications of Plant Growth Regulators and Hormones on Crop Resistance)

► Show Figures

Figure 1

13 pages, 2423 KiB

Open AccessEditor’s ChoiceArticle

Efficacy of Root Zone Temperature Increase in Root and Shoot Development and Hormone Changes in Different Maize Genotypes

by Zhenqing Xia, Guixin Zhang, Shibo Zhang, Qi Wang, Yafang Fu and Haidong Lu

Agriculture 2021, 11(6), 477; https://doi.org/10.3390/agriculture11060477 - 22 May 2021

Cited by 14 | Viewed by 2353

Abstract

In the context of global warming, the effects of warming in the root zone of crops on maize seedling characteristics deserve research attention. Previous studies on the adaptive traits of dryland maize have mainly focused on soil moisture and nutrients, rather than analyzing [...] Read more.

In the context of global warming, the effects of warming in the root zone of crops on maize seedling characteristics deserve research attention. Previous studies on the adaptive traits of dryland maize have mainly focused on soil moisture and nutrients, rather than analyzing potential factors for the adaptive traits of root zone warming. This study was conducted to investigate the effects of different root zone warming ranges on the agronomic traits, hormones, and microstructures of maize seedling roots and leaves. The results showed that minor increases in the root zone temperature significantly enhanced maize seedling growth. However, when the temperature in the root zone was excessive, the stem diameter, root surface area, root volume, total root length, dry matter accumulation, and root/shoot biomass of maize seedlings sharply decreased. Under high temperature stress in the root zone, the root conduit area; root stele diameter; root content of trans-zeatin (ZT), gibberellin A₃ (GA₃), and indoleacetic acid (IAA); leaf thickness; upper and lower epidermis thickness; and leaf content of ZT and GA₃ were significantly decreased. The hormone content and microstructure changes might be an important reason for root growth maldevelopment and nutrient absorption blockage, and they also affected the leaf growth of maize seedlings. Compared with the ‘senescent’ maize type Shaandan 902 (SD902), the plant microstructure of the ‘stay-green’ maize type Shaandan 609 (SD609) was less affected by increased temperatures, and the ability of the root system to absorb and transport water was stronger, which might explain its tolerance of high temperature stress in the root zone. Full article

(This article belongs to the Special Issue Applications of Plant Growth Regulators and Hormones on Crop Resistance)

► Show Figures

Figure 1

19 pages, 21324 KiB

Open AccessArticle

Strigolactone Alleviates Herbicide Toxicity via Maintaining Antioxidant Homeostasis in Watermelon (Citrullus lanatus)

by Abid Ali, Guy Kateta Malangisha, Haiyang Yang, Chen Li, Chi Wang, Yubin Yang, Ahmed Mahmoud, Jehanzeb Khan, Jinghua Yang, Zhongyuan Hu and Mingfang Zhang

Agriculture 2021, 11(5), 419; https://doi.org/10.3390/agriculture11050419 - 06 May 2021

Cited by 6 | Viewed by 2845

Abstract

Strigolactone (SL) plays essential roles in regulating plant growth, development, and stress response. This study was conducted to evaluate the effect of exogenous SL on watermelon resistance against herbicides penoxsulam (PXL) and bensulfuron-methyl (BSM). These herbicides were found to negatively impact watermelon root [...] Read more.

Strigolactone (SL) plays essential roles in regulating plant growth, development, and stress response. This study was conducted to evaluate the effect of exogenous SL on watermelon resistance against herbicides penoxsulam (PXL) and bensulfuron-methyl (BSM). These herbicides were found to negatively impact watermelon root growth and photosynthetic pigments, probably due to the ultrastructural damage and cell death in leaf and root tissues under herbicide stresses. The activation of SL-related gene expression suggested that the SL pathway may mitigate herbicide toxicity in watermelon. The exogenous SL dose-dependently reversed the PXL- or BSM-induced antioxidant activity, suggesting that SL may participate in maintaining antioxidant enzyme homeostasis under herbicide stresses. The up-regulation of herbicide metabolization and detoxification-related genes (cytochrome P450 and acetolactate synthase) by exogenous SL also in part explained how this phytohormone alleviates herbicide toxicity in watermelon. Our findings will provide valuable information underlying the regulatory effects of SL on herbicide tolerance in Cucurbitaceae crops. Full article

(This article belongs to the Special Issue Applications of Plant Growth Regulators and Hormones on Crop Resistance)

► Show Figures

Figure 1

Journal Menu

Journal Browser

Applications of Plant Growth Regulators and Hormones on Crop Resistance

Share This Special Issue

Special Issue Editor

Special Issue Information

Keywords

Published Papers (8 papers)

Research

Further Information

Guidelines

MDPI Initiatives

Follow MDPI