Physiological, Biochemical, and Transcriptomic Responses of Neolamarckia cadamba to Aluminum Stress

Abstract

Aluminum is the most abundant metal of the Earth’s crust accounting for 7% of its mass, and release of toxic Al3+ in acid soils restricts plant growth. Neolamarckia cadamba, a fast-growing tree, only grows in tropical regions with acidic soils. In this study, N. cadamba was treated with high concentrations of aluminum under acidic condition (pH 4.5) to study its physiological, biochemical, and molecular response mechanisms against high aluminum stress. High aluminum concentration resulted in significant inhibition of root growth with time in N. cadamba. The concentration of Al3+ ions in the root tip increased significantly and the distribution of absorbed Al3+ was observed in the root tip after Al stress. Meanwhile, the concentration of Ca, Mg, Mn, and Fe was significantly decreased, but P concentration increased. Aluminum stress increased activities of antioxidant enzymes such as superoxide dismutase (SOD), catalase from micrococcus lysodeiktic (CAT), and peroxidase (POD) in the root tip, while the content of MDA was decreased. Transcriptome analysis showed 37,478 differential expression genes (DEGs) and 4096 GOs terms significantly associated with treatments. The expression of genes regulating aluminum transport and abscisic acid synthesis was significantly upregulated; however, the genes involved in auxin synthesis were downregulated. Of note, the transcripts of several key enzymes affecting lignin monomer synthesis in phenylalanine pathway were upregulated. Our results shed light on the physiological and molecular mechanisms of aluminum stress tolerance in N. cadamba.

Physiological and Transcriptomic Responses of Growth in Neolamarckia cadamba Stimulated by Exogenous Gibberellins

“…Plant bud tissues were cultured to seedings in rooting medium (MS basal medium (M519, Phytotech, KS, USA) 3% sucrose, 0.01% inositol, 0.8% agar and 0.1 mg/L NAA) for 15 d in a tissue culture room with the light of 5000 luxe, and the seedings grown outdoors for 7 d to acclimatize a plant to the growth chamber. Then, the plants were removed from the medium and cleaned in the liquid medium, fixed with a sponge and foam board in a hydroponic box, and cultured with pure water in a growth chamber with 25 °C, 16 h-light (30,000 lux light intensity), 8 h-dark and 70% atmospheric humidity condition in the greenhouse for 7 days [ 33 ]. Plants were cultured with Hoagland liquid nutrient solution.…”

“…N. cadamba , a fast-growing member of the Rubiaceae family species, can grow into tall trees in a short time and have been widely planted and utilized in south Asia [ 29 , 30 ]. Previous research has found that various nutrient levels such as potassium (K), aluminum (Al), nitrogen (N), and boron (B) have a role in the regulation of N. cadamba growth [ 31 , 32 , 33 , 34 ]. Here, the response of N. cadamba to exogenous GAs is studied at the physiological and molecular levels.…”

Physiological and Transcriptomic Responses to Nitrogen Deficiency in Neolamarckia cadamba

“…The 4–5 cm tall seedlings were removed from the flasks, rinsed with tap water, and then fixed in a 6-L hydroponic box (length: 42 cm, width: 29 cm, and height: 7.5 cm) with a 1 cm 3 volume sponge and foam board and placed in a growth room. The plants were incubated for 7 days in 1/4 Hoagland nutrient solution after 7 days of incubation in tap water as described by Dai et al (2020) and Liu et al (2021) . The uniformed plants were finally selected and transferred into hydroponic boxes (length: 39 cm, width: 12 cm, and height: 10 cm) with a capacity of 2.5 L. Each box was fixed with a volume of 1 cm 3 sponge and foam board to fix 5 seedlings, 5 seedlings for one replicate, and three replicates each for the control and treatment groups at the 6th and 12th day, so 60 seedlings in total once time were aerated by an oxygen pump (10 h/day) and changed every 3 days.…”

“…The information of primers for the genes for quantitative PCR (qPCR) are listed in Supplementary Table 3 . SAMDC was chosen as the housekeeping gene ( Dai et al, 2020 ). The expression data were calculated by the 2 –ΔΔCt method ( Pfaffl, 2001 ).…”

Transcriptome Analysis Revealed the Mechanisms Involved in Ultrasonic Seed Treatment-Induced Aluminum Tolerance in Peanut

“…First, an exclusion mechanism involved the secretion of organic acids, phenolic compounds, phosphates, and so on for chelating Al 3+ into non-toxic compounds, thus preventing them from entering into root cells ( Liu, 2018 ; Fang et al, 2020 ; Chauhan et al, 2021 ). Second, the internal tolerance mechanism referred to that after Al 3+ enters the cytoplasm, the Al 3+ in the cells were transported to the vacuole through the transporter to isolate them from other organelles, and thus Al 3+ -induced disruptions to the plant body were reduced ( Zhang X. et al, 2019 ; Dai et al, 2020 ; Quimbaya et al, 2020 ). Two transporter families related to organic acid secretion, namely, multidrug and toxic compound extrusion ( MATE ), which regulates the secretion of citric acid, and aluminum-activated malate transporter ( ALMT ), which regulates the secretion of malate to chelate Al 3+ , respectively.…”