Journal of Plant Growth Regulation

Mickky, Bardees M.

doi: 10.1007/s00344-021-10403-5pmid: N/A

Seed priming was documented to effectively enhance crop performance with ultimate better yield under a wide range of environmental conditions. The current meta-analysis summarizes the findings of 2394 observations collected from 68 articles indexed on Web of Science database about the impact of different priming techniques on wheat yield under different forms of abiotic stress. Economic yield (EY), biological yield (BY), and thousand-kernel mass (TKM) were the yield parameters extracted from the analyzed articles. Heterogeneity test indicated high consistency of the collected observations. Analysis metrics revealed general enhancement of EY of stressed wheat plants by 29%, BY by 22%, and TKM by 16% due to seed priming. Under stress, redox halopriming caused the maximum enhancement in both EY and BY, while osmopriming caused the maximum enhancement in TKM. Moreover, seed priming caused the maximum enhancement in both EY and BY under alkali stress; and the maximum enhancement in TKM under heavy metal stress. The current meta-analysis thus emphasizes the efficiency of seed priming in improving wheat yield under stress with recommending further exploit of redox halopriming, nanopriming, and thermopriming in this aspect especially under cold stress.

Adeleke, Bartholomew Saanu; Babalola, Olubukola Oluranti

doi: 10.1007/s00344-021-10406-2pmid: N/A

Despite the importance of diverse plant growth-promoting endophytes in agricultural production, their biotechnological and agricultural applications are not well-documented. The diversity of microbial communities interacting with the endosphere contributes to plant functions and immunity, leading to higher productivity. Plant-microbe interactions range from beneficial in terms of influencing plant growth to harmful, as they also cause plant diseases. Microbial survival in the internal tissues of plants depends on their colonization tendencies and their ability to compete with the indigenous plant microflora. The infiltration of microbes through the external soil-root environment into the plant endosphere significantly enhances growth-promoting attributes of plants such as antibiosis, siderophore production, induced systemic resistance, bioremediation and growth hormones synthesis. However, the growth and diversity of endophytic microbes are influenced by the availability of soil nutrients, presence of pathogens, plant growth stages, plant genome, and other abiotic factors. Knowledge and understanding of the possible use and biotechnological relevance of endosphere communities in sustainable agriculture cannot be overemphasized. Hence, this review discusses the importance of endophytic microbes in agriculture for enhancing crop productivity.

Dowarah, Bhaskar; Gill, Sarvajeet Singh; Agarwala, Niraj

doi: 10.1007/s00344-021-10392-5pmid: N/A

Mycorrhiza is a symbiotic association between the roots of plants with fungi. Among the various types of mycorrhizal fungi, arbuscular mycorrhizal fungi (AMF) are the most prominent as they are obligate symbionts with a wide host range, and they play a major role in shaping ecosystems and associated productivity. Approximately 71% of vascular plant species are able to form symbiotic association with AMF. AMF primarily rely on the host for photosynthates but give much more in return for the well-being of the host plant. Most importantly they are able to improve tolerance of host plants against various biotic stresses, such as—bacterial, fungal, viral, nematode phytopathogens and herbivores. The underlying mechanism includes—competition for nutrients, space, and host photosynthates, rhizosphere alteration and host defense induction. The effectiveness of an AM association in conferring biotic stress tolerance is context dependent, affected by various biotic and abiotic factors. This review describes various mechanisms involved in AMF mediated biotic stress tolerance in plant and the biotic and abiotic factors which influences the performance of AM association.

Afzal, Shadma; Aftab, Tariq; Singh, Nand K.

doi: 10.1007/s00344-021-10388-1pmid: N/A

Sustainable use of nanoparticles (NPs) in agricultural sector requires knowledge of probable harmful impacts of NPs and the crop’s life cycle. Delivery pathways of NPs play an important role in NPs uptake in plants. The foliar pathway of NPs uptake, translocation and accumulation is even less documented than the soil to root pathway. In this study, biocompatible zinc oxide NPs (ZnO NPs) and iron oxide NPs (FeO NPs) have been phytosynthesized using Senna occidentalis L. leaf extract. Different characterization techniques such as XRD, PSA, FTIR, FE-SEM and AFM were used to show efficacious synthesis of NPs capped with phytochemicals. The key objective of this study was to equate the effect of the synthesized ZnO (37 ± 2 nm) and FeO NPs (27 ± 2 nm) over a concentration (10, 50, 100 and 500 mg L−1) range by foliar and root exposure methods on physiological and biochemical parameters, as well as on uptake, translocation and accretion of NPs in different rice plant parts. The results showed that there is a critical concentration of NPs up to which the rice crop growth is promoted with no enhancement beyond that. Foliar treatment was found to be more effective than the root treatment with respect to uptake of the NPs in plants. NPs uptake, translocation and consequential plant responses are also discussed.

Makkar, Harshita; Arora, Sakshi; Khuman, Aniruddhabhai K.; Chaudhary, Bhupendra

doi: 10.1007/s00344-021-10376-5pmid: N/A

In response to environmental and cellular cues, the spatiotemporal expression of differentially expressed miRNAs (DEmiRs) during in vitro regeneration of plants is prominent. Nevertheless, the influence of stress conditions on the functional imprints of DEmiRs during plant organogenesis is inadequately understood. Target-mimicry based constitutive diminution of miR167 genes in transgenic tobacco revealed their functional contributions in salt-stress tolerance during organogenesis. Up to 61.6% relative increment in the shoot emergence on leaf explants of miR167 mimic lines (cultured on 12.5 and 25 mM NaCl concentrations) exhibited greater magnitude of organogenesis under stress, most probably through upregulated auxin signalling. Relativeexpression analysis of auxin transporter genes AUX1, PIN1 and PIN2 revealed synergistic effect of percent miR167 diminution and salt-stress (up to 12.5 mM) resulting into enhanced callogenesis and reduced organogenesis. Biochemical assessment of in vitro grown miR167 mimic shoot initials revealed an increase in the relative water content, chlorophyll and antioxidant activity, which suggested a shift in the molecular equilibrium in response to miR167 diminution-associated signalling pathways. Remarkably, independent miR167 diminution lines exhibited expression variations among associated miR156, miR159, and miR394 and validated by the expression analysis of selected target genes SPL9, ARF6 and ARF8. The expression ratios of these miRNAs revealed their coordinated regulatory network in response to salt-stress during organogenesis. These results demonstrate a link between miR167 diminution and salt-stress tolerance in mimic lines, and suggest that a regulatory shift in the cellular metabolism may contribute to salt-stress tolerance in plants. These observations may create new avenues for strategic utilization of such genic resources for future crop research.

Ahiakpa, John Kojo; Magdy, Mahmoud; Karikari, Benjamin; Munir, Shoaib; Mumtaz, Muhammad Ali; Tamim, Safir Ahmad; Mahmood, Saira; Liu, Genzhong; Chen, Weifang; Wang, Ying; Zhang, Yuyang

doi: 10.1007/s00344-021-10384-5

Sihi, Sayantani; Bakshi, Sankar; Maiti, Soumitra; Nayak, Arup; Sengupta, Dibyendu Narayan

doi: 10.1007/s00344-021-10390-7pmid: N/A

The plants are constantly subjected to varying degree of environmental stress. These stresses results in severe damage to the DNA of the plants, which if not repaired can lead to the impairment of their genetic material, and can prove fatal for the plants. The present work studies the damage to the genomic DNA in response to salinity and drought stress on the indica rice cultivars. The comet assay results showed that maximum DNA damage was seen in the IR29 cultivar, whereas, the Nonabokra cultivar showed minimal DNA damage. The gene expression profiling of DNA polymerase λ (OsPolλ), the only X family DNA polymerase in rice which is involved in the repair of DNA damage, shows that the gene is up-regulated in all the rice cultivars irrespective of their degree of tolerance to the environmental stresses. Further the enzymatic activity of the OsPolλ protein was studied in the three rice cultivars and it was revealed that the OsPolλ activity increases in response to stresses in all the rice cultivars, however, the salinity-susceptible IR29 showed a more prominent increases in the activity of OsPolλ than Nonabokra (salinity tolerant) and N22 (drought tolerant) cultivars. The study on the upstream regions of the OsPolλ gene to identify the different cis acting upstream elements effecting the gene expression showed the presence of unique stress responsive regulatory elements was detected in the upstream region of OsPolλ gene. The present study suggest that the OsPolλ gene expression and enzymatic activity is enhanced in response to these abiotic stress, thus, playing an important role in the repair of salinity and drought induced DNA damages in indica rice cultivars.

Moussa, Mohamed G.; Sun, Xuecheng; Ismael, Marwa A.; Elyamine, Ali Mohamed; Rana, Muhammad Shoaib; Syaifudin, Muhamad; Hu, Chengxiao

doi: 10.1007/s00344-021-10397-0pmid: N/A

Molybdenum (Mo) is an essential element for the growth and development of higher plants. Its deficiency leads to a decrease in wheat (Triticum aestivum L.) growth and reduces nutritional quality of grain. However, little is known about macro- and micro-nutrient contents or their allocation within organs of wheat under Mo sufficient and deficient conditions. The objective of this study was to gain a better understanding of how Mo application affects mineral nutrient uptake and allocations among various organs of wheat. A pot experiment was conducted to explore these effects in wheat with Mo-deficiency (–Mo) and Mo supply (+ Mo) treatment. The results revealed that Mo application increased plant dry biomass, grain yield, allocations of macro-nutrients (nitrogen (N), phosphorus (P), and potassium (K)), and micro-nutrients (copper (Cu), iron (Fe), manganese (Mn), zinc (Zn), and molybdenum (Mo)) among different wheat organs except for Fe. Nutrient allocation to plant tissues also varied between different organs. A high allocation of N, P, and Zn was observed in grain, K and Cu higher allocation was found in the stem, while flag leaf and glumes accumulated higher content of Mn and Mo, under Mo application as compared with Mo deficiency treatment. Mo application increased the uptake of N, P, K, Cu, Fe, Mn, Zn, and Mo in wheat organs compared to –Mo treatment. The relative increase of N, P, K, Cu, Fe, Mn, Zn and Mo uptake in the wheat grains was 58.5%, 13.0%, 29.7%, 20.2%, 31.5%, 12.7%, 52.8% and 621%, while in the flag leaf was 199.1%, 198.5%, 203.4%, 713.7%, 281.0%, 179.1%, 128.6% and 431.5%, respectively. The research findings suggest the supportive role of Mo application in increasing macro- and micro-nutrient uptake among wheat organs and grain yield through improving macro–micro-nutrient allocations.

Yang, Jun; Duan, Licheng; He, Haohua; Li, Yingchun; Li, Xiangxiang; Liu, Dan; Wang, Jianjun; Jin, Guohua; Huang, Shue

doi: 10.1007/s00344-021-10399-ypmid: N/A

High temperature (HT) severely limits rice production, but effective measures can reduce the adverse effects of HT. A 2-year experiment was conducted involving five sowing dates to investigate the effects of potassium dihydrogen phosphate (KH2PO4), salicylic acid (SA), and the sowing date on the physiological characteristics, yield and quality of rice subjected to HT. Under ambient HT conditions (daily average temperature ≥ 30 °C for ≥ 3 days or maximum temperature ≥ 35 °C for ≥ 3 days), KH2PO4 (KP1-KP2: 22.05 and 36.75 mmol L−1), SA (SA1-SA2: 0.5 and 1.5 mmol L−1), and their combinations were applied to leaves from the late-booting stage to the flowering stage, with deionized water as a control (CK). Compared with CK, KP1, KP2, SA1, KP1 + SA1, and KP2 + SA1 alleviated the adverse effects of HT on the number of grains per panicle, seed set, and yield, among which SA1, KP2 + SA1, and KP1 were the best. The antioxidant enzyme (superoxide dismutase, peroxidase, and catalase) activities, levels of osmotic protective substances (soluble sugars, soluble proteins, and proline), and chlorophyll content were increased and the malonaldehyde content and leaf temperature were decreased in the SA1, KP2 + SA1, and KP1 treatments. Compared with those sown on April 25 and May 5, plants sown on May 15, May 25, and June 5 had suitable temperature conditions and presented increased grain yield and quality. Therefore, the application of SA1, KP2 + SA1, and KP1 and the use of an optimal sowing date (from May 15 to June 5) increased the rice yield and quality under HT.

Omidian, Mojgan; Roein, Zeynab; Shiri, Mohammad Ali

doi: 10.1007/s00344-021-10400-8pmid: N/A

Lilium (lily) is known as an important cut flower whose quality and ornamental value may be negatively affected by deficit irrigation (DI); however, the adverse effects of DI could be alleviated by exogenous application of 24-epibrassinolide (EBR). Therefore, we conducted the present research to study the effects of different levels of soil water content (SWC) [100% (full irrigation), 75% (low DI), 50% (moderate DI), and 25% (severe DI)] and foliar spray of EBR (0.0, 0.75 and 1.5 μM) on certain morpho-physiological characteristics of Lilium “Fangio” (LA hybrid, Longiflorum x Asiatic). Different levels of DI were observed to alter lily’s morphological characteristics, affecting biochemical and physiological indices. Severe DI reduced plant height (11.11%), pedicel length (33.51%), and flower number (13.57%) while it increased the accumulation of proline (115.78%), electrolyte leakage (EL; 79.68%), and malondialdehyde (MDA; 40.35%) content. It also increased the water use efficiency (WUE; 135.59%) and saved water (66.7%). Foliar application of EBR significantly decreased the content of MDA (32.87%), on top of enhancing proline content (37.03%) and WUE (20.25%). The application of EBR (1.5 μM) on water stressed lily plants resulted in the improvement of chlorophyll content (41.46%) and activities of antioxidant enzymes (CAT and APX). Our results confirmed that applying irrigation at 75% SWC could reduce water inputs without affecting the ornamental value of lily. Overall, lily showed a moderate level of tolerance to water deficit by various mechanisms, such as a decrease of morphological parameters, maintenance of physiological function, an increase in WUE, and accumulation of osmolytes and enzymatic antioxidants. It could be concluded that severe water stress has to be avoided throughout the growing season of lilies, and if a foliar spray of EBR is used for the modulation and alleviation of the detrimental effects of drought stress, only moderate deficits are acceptable.