Open AccessExogenous application of brassinosteroids regulates tobacco leaf size and expansion via modulation of endogenous hormones content and gene expression
Author(s) -
Juan Zhang,
Yan Zhang,
Rayyan Khan,
Xiaoying Wu,
Lei Zhou,
Na Xu,
Shanshan Du,
Xiaoran Ma
Publication year - 2021
Publication title -
physiology and molecular biology of plants/physiology and molecular biology of plants
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.754
H-Index - 35
eISSN - 0971-5894
pISSN - 0974-0430
DOI - 10.1007/s12298-021-00971-x
Subject(s) - brassinosteroid , gibberellin , downregulation and upregulation , auxin , biology , endogeny , cell growth , microbiology and biotechnology , cell , gene expression , plant physiology , botany , gene , biochemistry , arabidopsis , mutant
Brassinosteroids (BR) play diverse roles in the regulation of plant growth and development. BR promotes plant growth by triggering cell division and expansion. However, the effect of exogenous BR application on the leaf size and expansion of tobacco is unknown. Tobacco seedlings are treated with different concentrations of exogenous 2,4-epibrassinolide (EBL) [control (CK, 0 mol L -1 ), T1 (0.5 × 10 -7 mol L -1 ), and T2 (0.5 × 10 -4 mol L -1 )]. The results show that T1 has 17.29% and T2 has 25.99% more leaf area than control. The epidermal cell area is increased by 24.40% and 17.13% while the number of epidermal cells is 7.06% and 21.06% higher in T1 and T2, respectively, relative to control. So the exogenous EBL application improves the leaf area by increasing cell numbers and cell area. The endogenous BR (7.5 times and 68.4 times), auxin (IAA) (4.03% and 25.29%), and gibberellin (GA 3 ) contents (84.42% and 91.76%) are higher in T1 and T2, respectively, in comparison with control. Additionally, NtBRI1 , NtBIN2 , and NtBES1 are upregulated showing that the brassinosteroid signaling pathway is activated. Furthermore, the expression of the key biosynthesis-related genes of BR ( NtDWF4 ), IAA ( NtYUCCA6 ), and GA 3 ( NtGA3ox-2 ) are all upregulated under EBL application. Finally, the exogenous EBL application also upregulated the expression of cell growth-related genes ( NtCYCD3;1 , NtARGOS , NtGRF5 , NtGRF8 , and NtXTH ). The results reveal that the EBL application increases the leaf size and expansion by promoting the cell expansion and division through higher BR, IAA, and GA 3 contents along with the upregulation of cell growth-related genes. The results of the study provide a scientific basis for the effect of EBL on tobacco leaf growth at morphological, anatomical, biochemical, and molecular levels.