Spermidine Suppressed the Inhibitory Effects of Polyamines Inhibitors Combination in Maize (Zea mays L.) Seedlings under Chilling Stress

Abstract

Chilling stress greatly inhibited the seed germination, plant growth, development and productivity in this study. The current research aimed to study the effects of different polyamine (PA) inhibitor combinations (Co), e.g., D-arginine (D-Arg), difluoromethylormithine (DFMO), aminoguanidine (Ag) and methylglyoxyl–bis-(guanyhydrazone) (MGBG) at different doses, i.e., 10 µM Co, 100 µM Co, 500 µM Co, 1000 µM Co and 1000 µM Co + 1 mM Spd (Spermidine) in two inbred lines of maize (Zea mays L.), i.e., Mo17 and Huang C, a sensitive and tolerant chilling stress, respectively. The combination treatments of PA inhibitors reduced the biosynthesis of putrescine (Put) in the tissues of both studied inbred lines. Application with 500 µM Co and 1000 µM Co did not result in a significant difference in Put concentrations, except in the coleoptile of Mo17. However, combining Spd to 1000 μM of PA inhibitors enhanced the Put, Spd, spermine (Spm) and total PAs in the roots, coleoptile and mesocotyls. Put and total PAs were increased by 39.7% and 30.54%, respectively, when Spd + 1000 µM Co were applied relative to their controls. Chilling stress and PA inhibitors treatments affected both inbred lines and resulted in differences in the PA contents. Results showed that enzymes involved in the biosynthesis of PAs (ornithine decarboxylase as ODC and S-adenosylmethionine decarboxylase as SAMDC) were significantly downregulated by 1000 µM Co in the tissues of both inbred lines. In contrast, the activity of PAO, a Pas degradation enzyme, was significantly improved by 1000 µM Co under chilling stress. However, Spd + 1000 µM Co significantly improved the activities of ODC and SAMDC and their transcript levels (ODC and SAMDC2). While it significantly downregulated the PAO activity and their relative genes (PAO1, PAO2 and PAO3) under chilling stress. Overall, this study elucidates the specific roles of Spd on the pathway of PA inhibitors and PA biosynthesis metabolism in maize seed development in response to chilling stress. Moreover, the Huang C inbred line was more tolerant than Mo17, which was reflected by higher activities of PA biosynthesis-related enzymes and lower activities of PAs’ degradative-related enzymes in Huang C.

Understanding and Comprehensive Evaluation of Cold Resistance in the Seedlings of Multiple Maize Genotypes

“…Our study correlated well with these studies as 10 °C stress significantly promoted Put, Spd, and Spm accumulation (56.6–183.7%) in leaves of maize seedlings. Gao et al [ 12 ] reported that ZmADC1 , ZmADC2 , ZmODC , ZmSPDS , ZmSAMDC2 , ZmPAO1 , ZmPAO2 , and ZmPAO3 responded to biosynthesis and catabolism of PAs in maize under cold stress, which was also consistent with the expressions of GRMZM2G396553 , GRMZM2G120578 , and GRMZM2G396856 in M0504 and M1012 under 10 °C and 22 °C treatments. Thereby, these results provide a molecular basis for the utilization of PA–related genes to improve maize cold resistance in the future.…”

“…PAs are small aliphatic low–molecular weight polycationic nitrogenous compounds that played critical roles in chilling tolerance in plants [ 12 , 13 , 14 ]. Upon exposure to low temperature, the concentrations of putrescine (Put), Spd, and Spm significantly increased by 183.7%, 69.2%, and 56.6% in leaves of 39 maize genotypes seedlings, respectively ( Figure 1 and Figure 2 ).…”

“…According to the results of previous studies [ 1 , 2 , 3 , 4 , 5 , 6 , 12 , 13 , 14 , 16 , 17 , 23 , 28 , 38 , 39 , 46 ] and our Pearson correlation and PCA analyses in the current study, distinct physiological processes and organ systems were involved in the onset, accumulation, and/or repair of maize cold injury; concomitantly, distinct molecular mechanisms were also likely involved in preventing (i.e., resistance) versus repairing cold injury (i.e., tolerance) by activating and inducing the expressions of some cold-responsive genes [ 47 ]. A diagram of hypothetical complex response mechanisms on cold resistance in maize was constructed ( Figure 6 ).…”

“…The rapid accumulation of Pro was the initial reaction of plants exposed to the cold condition [ 9 ]. Interestingly, previous studies also reported that polyamines (PAs) were involved in several physiological and developmental processes in plants, such as survival of plant embryos and translation [ 10 ], cell proliferation [ 11 ], modulated gene expression [ 12 ], membrane stabilization [ 13 ], and chilling stress response [ 11 ]. In recent years, only a few studies have shown that increasing PA concentrations in maize [ 12 , 13 , 14 ] could improve its resistance to low-temperature stress.…”

Salvianolic Acid Modulates Physiological Responses and Stress-Related Genes That Affect Osmotic Stress Tolerance in Glycine max and Zea mays

“…Several NAC members have been practically distinguished in the developmental programs (Souer et al, 1996 ; Aida et al, 1997 ; Takada et al, 2001 ; Weir et al, 2004 ), growth hormone signaling (Xie et al, 2000 ; Fujita et al, 2004 ), defense (Collinge and Boller, 2001 ; Hegedus et al, 2003 ), and leaf senescence (Fraga et al, 2021 ). Various NAC genes participate in reactions to abiotic stresses, which include flood, water deficit, salinity, and cold (Fujita et al, 2004 ; Olsen et al, 2005 ; Hu et al, 2006 ; He et al, 2017 ; Gao et al, 2020 , 2021 ; Mao et al, 2021 ). Enhanced expression of ZmNAC48 was detected in maize plants subjected to osmotic stress.…”