Aluminum-induced programmed cell death promoted by AhSAG, a senescence-associated gene in Arachis hypoganea L

Abstract

Programmed cell death (PCD) is a foundational cellular process in plant development and elimination of damaged cells under environmental stresses. In this study, Al induced PCD in two peanut (Arachis hypoganea L.) cultivars Zhonghua 2 (Al-sensitive) and 99-1507 (Al-tolerant) using DNA ladder, TUNEL detection and electron microscopy. The concentration of Al-induced PCD was lower in Zhonghua 2 than in 99-1507. AhSAG, a senescence-associated gene was isolated from cDNA library of Al-stressed peanut with PCD. Open reading frame (ORF) of AhSAG was 474bp, encoding a SAG protein composed of 157 amino acids. Compared to the control and the antisense transgenic tobacco plants, the fast development and blossom of the sense transgenic plants happened to promote senescence. The ability of Al tolerance in sense transgenic tobacco was lower than in antisense transgenic tobacco according to root elongation and Al content analysis. The expression of AhSAG-GFP was higher in sense transgenic tobacco than in antisense transgenic tobacco. Altogether, these results indicated that there was a negative relationship between Al-induced PCD and Al-resistance in peanut, and the AhSAG could induce or promote the occurrence of PCD in plants.

Keywords: APX; AhSAG; Al; CAT; Ca(2+)-ATPase; Ca(2+)-adenosine-5′-triphosphatase; EB; EDTA; MDA; ORF; PBS; PCD; PCR; POD; Peanut; ROS; SDS; SOD; TEM; TUNEL; TdT-mediated deoxy-uracil nick end labeling; Transgenic tobacco; Tris; aa; aluminum; amino acid; ascorbate peroxidase; catalase; dNTP; deoxyribonucleoside triphosphate; ethidium bromide; ethylene diaminetetraacetic acid; kb; kilobase; malondialdehyde; open reading frame; peroxidase; phosphate buffer saline; polymerase chain reaction; programmed cell death; reactive oxygen species; sodium dodecyl sulfate; superoxide dismutase; transmission electron microscopy; tris(hydroxymethyl)aminomethane.