Functional Analysis of Potato CPD Gene: A Rate‐Limiting Enzyme in Brassinosteroid Biosynthesis under Polyethylene Glycol‐Induced Osmotic Stress

Abstract

The constitutive photomorphogenesis and dwarf (CPD) gene was initially isolated from an Arabidopsis thaliana (L.) Heynh. cpd mutant and encodes C‐3 oxidase as a key rate‐limiting enzyme in the brassinosteroids (BRs) biosynthesis pathway. For a better understanding of the molecular mechanism of CPD gene overexpression in potato (Solanum tuberosum L.) and CPD‐overexpressing potato plant tolerance to polyethylene glycol (PEG)‐induced osmotic stress, CPD gene was cloned by reverse transcription–polymerase chain reaction (RT‐PCR) from potato. The coding region was 1473 bp and encoded a deduced protein of 490 amino acids. The transgenic potato plants with CPD gene overexpression were obtained. Quantitative real‐time polymerase chain reaction (qRT‐PCR) analysis indicated that the CPD gene expressed in the roots, stems, and leaves of the transgenic and nontransgenic (NT) plants with particularly enhanced expression in the leaves. The proline content was 0.18‐ to 0.62‐fold higher and the malonaldedyde (MDA) content decreased by 45.1 to 87.4% in CPD‐overexpressing potato plants than in the NT plants under PEG‐induced osmotic stress conditions. The soluble sugar content, soluble protein content, and the superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), glutathione reductase (GR), and ascorbate peroxidase (APX) activities were all greater in the drought‐stressed transgenic plantlets at different sampling times than in the NT seedlings. These results indicated that CPD gene overexpression could ameliorate the effects of PEG‐induced osmotic stress. These results lay the foundation for further research on BR regulation in potato development and growth.

PscCYP716A1-Mediated Brassinolide Biosynthesis Increases Cadmium Tolerance and Enrichment in Poplar

“…Based on the potential functions of exogenous BR and our results, we thought that PscCYP716A1 strengthened the oxidative defense system by mediating endogenous BR biosynthesis, which declined ROS accumulation and enhanced the plant's tolerance to Cd. The same mechanism also was reported in a recent investigation that the overexpression of the CPD gene involved in C-3 oxidase of the BR biosynthesis pathway significantly elevated the activities of antioxidant enzymes (SOD, POD, CAT, GR, and APX) to resist oxidative injury under drought stress (Zhou et al, 2016). When fruits were exposed to cold storage conditions, the SlCYP90B3 gene, which participates in the early stage of the C-22 α-hydroxylation in BR biosynthesis, increased the chilling tolerance of fruits through aggrandizing antioxidant system (Hu et al, 2022).…”

Drought-tolerant and drought-sensitive genotypes of maize (Zea mays L.) differ in contents of endogenous brassinosteroids and their drought-induced changes

“…Some authors who worked with BR mutants, transgenic plants or plants treated with exogenous BRs and subjected to drought conditions, assessed the levels of a few specific transcripts presumed to be correlated to plant drought response. These studies were made with Arabidopsis [ 76 ], rapeseed [ 76 , 77 ], cucumber [ 78 ], tobacco [ 79 ], potato [ 80 ], Brachypodium [ 81 ] or barley [ 82 ]. However, with the exception of Zhou et al ., who found gradual increase in the levels of CPD transcripts during the first 24 hours of PEG-induced osmotic stress in potato (and subsequent drop to the original level after additional 24 hours) [ 80 ], the expression of BR biosynthetic or signaling genes in drought-stressed plants had not yet been purposefully analysed.…”

Crosstalk between phytohormones and secondary metabolites in the drought stress tolerance of crop plants: A review

“…and DWARF from Arabidopsis (AtCPD, a C3-OXIDASE) provides drought tolerance by modulating proline, MDA, soluble sugars, and antioxidant system in potato (Zhou, Zhang, et al, 2016). Similarly, the maize mutated in C6-OXIDASE, lilliputian1-1, has higher sensitivity to drought stress (Castorina et al, 2018).…”

“…Overexpression of the Arabidopsis BR biosynthesis gene AtDWARF4 improved drought tolerance in Brassica napus (Sahni et al, 2016). Overexpression of CONSTITUTIVE PHOTOMORPHOGENESIS ( COP ) and DWARF from Arabidopsis ( AtCPD , a C3‐OXIDASE ) provides drought tolerance by modulating proline, MDA, soluble sugars, and antioxidant system in potato (Zhou, Zhang, et al, 2016). Similarly, the maize mutated in C6‐OXIDASE , lilliputian1‐1 , has higher sensitivity to drought stress (Castorina et al, 2018).…”