AUTHOR=Al-Zahrani Hassan S. , Alharby Hesham F. , Fahad Shah 

TITLE=Antioxidative Defense System, Hormones, and Metabolite Accumulation in Different Plant Parts of Two Contrasting Rice Cultivars as Influenced by Plant Growth Regulators Under Heat Stress

JOURNAL=Frontiers in Plant Science

VOLUME=Volume 13 - 2022

YEAR=2022

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2022.911846

DOI=10.3389/fpls.2022.911846

ISSN=1664-462X

ABSTRACT=We examined the metobloic, hormonal, enzymatic and non-enzymatic  responses of various plant components (leaf, root and xylem sap)  to  plant growth regulators [methyl jasmonates (MeJA); ascorbic acid (Vc); brassinosteroids (Br); triazoles (Tr); alpha-tocopherol (Ve) and control] under heat stress [ambient temperature (AT), heat stress at night time(HNT) and high stress at day (HDT)] in heat sensitive (IR-64) and tolerant (Huanghuazhan) rice cultivars under greenhouse condition. Heat stress altered the antioxidant activities and hormonal balance, and rigorously reduced total soluble sugars, proteins, and proline, while increased H2O2 and MDA accumulation in the plant xylem sap and leaves of both tested cultivars but the their impact was more pronounced in IR-64. The SOD, POD, CAT, APX, GR,  GSH, DHAR, and MDHAR activities were comparatively higher in Huanghuazhan than IR-64 in response  to temperature stress when  compared to AT. Heat stress increased ABA levels in both rice cultivars especially in IR-64. The highest concentrations of hormones were recorded in roots followed by leaf and xylem sap in both cultivars. The HDT and HNT stresses severely reduced the concentrations of all cytokinin types (except iP9G and tZ9G), and IAA in different plant parts of rice cultivars. The HNT was more detrimental for hormones and metabolites synthesis in both cultivars. The growth regulators  especially Vc+Br+Ve+MeJA were comparatively more effective in minimizing the hostile impact of heat stress in most of the studied traits and shall be applied for obtaining optimum yield of rice in subtropical and tropical areas under changing climatic conditions.