Stress-induced co-expression of two alternative oxidases (VuAox1 and 2b) in Vigna unguiculata

COSTA, J.H., FREITAS MOTA, E., CAMBURSANOB, M.V., LAUXMANN, M.A., NOGUEIRA DE OLIVEIRA, L.M., SILVA LIMA, M.G., ORELLANO, E.G. & FERNANDES DE MELO, D.

JOURNAL OF PLANT PHYSIOLOGY

ELSEVIER GMBH

Año: 2010

0176-1617

<!-- /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0cm; margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:12.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman"; mso-ansi-language:PT-BR; mso-fareast-language:PT-BR;} p {mso-margin-top-alt:auto; margin-right:0cm; mso-margin-bottom-alt:auto; margin-left:0cm; mso-pagination:widow-orphan; font-size:12.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman"; mso-ansi-language:PT-BR; mso-fareast-language:PT-BR;} @page Section1 {size:612.0pt 792.0pt; margin:70.85pt 3.0cm 70.85pt 3.0cm; mso-header-margin:36.0pt; mso-footer-margin:36.0pt; mso-paper-source:0;} div.Section1 {page:Section1;} --> Vigna unguiculata alternative oxidase is encoded by a small multigene family (Aox1, Aox2a and 2b) orthologous to soybean Aox family. The structure of VuAox1 and VuAox2-type genes consists of 4 exons interrupted by 3 introns as the majority of plant Aox. An alignment of the orthologous Aox genes revealed exons high identity and an intron variability which is more prevalent in Aox1. In order to highlight Aox gene expression in V. unguiculata a transcript steady state analysis was performed in seed formation and development (flowers, pods and dry seeds) and germination (soaked seeds) revealing already VuAox1 and VuAox2b co-expression in a systemic manner during germination. Further, the analysis of Aox transcripts in leaves from seedlings under several conditions (cold, drought, salicylate and H2O2) showed a stress-induced co-expression of VuAox1 and VuAox2b. Estimated primary transcript lengths of V. unguiculata and soybean Aox genes revealed an intron length reduction to reach similar lengths for VuAox1 and VuAox2b supporting the idea of genome design to “economy selection” and “time synchronicity” to establish a co-expression. Indeed, a bioinformatics approach with VuAox1 and VuAox2b promoters revealed a conserved region related to a cis-element responsive to oxidative stress. Taken altogether, the data provide evidences for postulating by the first time an Aox1 and Aox2 co-expression responsive to stress as either as the first stages of seed germination.