Carotenoid deficiency impairs ABA and IAA biosynthesis and differentially affects drought and cold tolerance in rice

Abstract

Plant responses to abiotic stresses are coordinated by arrays of growth and developmental programs. Phytohormones such as abscisic acid (ABA) and indole-3-acetic acid (IAA) play critical roles in developmental progresses and environmental responses through complex signalling networks. However, crosstalk between the two hormones at the biosynthesis level remains largely unknown. Here, we report that carotenoid-deficient mutants (phs1, phs2, phs3-1, phs4, and PDS-RNAi transgenic rice) were impaired in the biosynthesis of ABA and IAA. Under drought conditions, phs3-1 and PDS-RNAi transgenic rice showed larger stomata aperture and earlier wilting compared to the wild type at both seedling and panicle developmental stage. Interestingly, these carotenoid-deficient lines showed increased cold resistance, which was likely due to the combined effects of reduced IAA content, alleviated oxidative damage and decreased membrane penetrability. Furthermore, we found that IAA content was significantly declined in rice treated with fluridone (a carotenoid and ABA biosynthesis inhibitor), and expression of auxin synthesis and metabolism-related genes were altered in the fluridone-treated rice similar to that in the carotenoid-deficient mutants. In addition, exogenous IAA, but not ABA, could restore the dwarf phenotype of phs3-1 and PDS-RNAi transgenic rice. These results support a crosstalk between ABA and IAA at the biosynthesis level, and this crosstalk is involved in development and differentially affects drought and cold tolerance in rice.

The effect of triazole induced photosynthetic pigments and biochemical constituents of Zea mays L. (Maize) under drought stress

“…In the transcription factors interact with specific cis-acting elements existing in target gene promoters and regulate elaborate networks of drought-responsive genes and associated biochemical and physiological adaptations (yang et al 2014). Most of these adaptation responses are determined by several secondary messengers including some plant hormones (Qin et al 2011;Du et al 2013). Diverse sets of genes expressed in response to abiotic stress have been identified, and elucidation of their physiological or cellular roles in terms of either stress tolerance or sensitivity is a critical issue in current plant biology (Huang et al 2012;Jirschitzka et al 2013).…”

Emerging Roles of Auxin in Abiotic Stress Responses

“…Overexpression of OsGH3-2 resulted in IAA-defi cient phenotype but resistant to cold stress (Du et al 2012 ). Similarly, carotenoid-defi cient rice phs1 , phs2 , phs3-1 , phs4 , and PDS-RNAi transgenic rice showed ABA and IAA biosynthesis defi ciency and showed similar phenotypes to OsGH3-2 overexpression plants against drought and cold (Du et al 2013b ). To conclude, it can be suggested that local auxin gradients link auxin responses and developmental changes under cold stress.…”

“…However, the o verexpression lines showed greater tolerance to cold. Carotenoid-defi cient rice phs1 , phs2 , phs3-1 , phs4 , and PDS-RNAi transgenic rice showed ABA and IAA biosynthesis defi ciency and thus showed similar phenotypes to OsGH3-2 overexpression plants against drought and cold (Du et al 2013b ). Thus, a possible crosstalk modulated by ABA and IAA levels can affect drought responses of plants.…”

“…This effect was due to modulation of endogenous free IAA levels and ABA homeostasis (Du et al 2012 ). Carotenoid-defi cient mutant lines with lower auxin level exhibited tolerance to cold stress (Du et al 2013b ). Yuan et al ( 2013 ) also documented the decline in endogenous auxin level under cold and salinity stresses in leaves and roots of Malus sieversii.…”

“…OsGH3-2 overexpression in rice imparted tolerance to cold and showed morphological aberrations, IAA defi ciency and reduced carotene, ABA and free IAA levels and ABA homeostasis (Du et al 2012 ). Carotenoid-defi cient mutant lines exhibited tolerance to cold stress with lower auxin level (Du et al 2013b ). Overexpression of YUCCA6 in transgenic potato showed increased endogenous auxin level and enhanced drought stress tolerance (Kim et al 2013 ).…”