Influence of plant growth regulators on Expansin2 expression in strawberry fruit. Cloning and functional analysis of FaEXP2 promoter region?.

NARDI, C.F.*; VILLARREAL, N.M.* (PRIMERA CO-AUTORA); DOTTO, M.C.*; ARIZA, M.T.; VALLARINO, J.G.; MARTÍNEZ, G.A.; VALPUESTA, V.; CIVELLO, P.M.

POSTHARVEST BIOLOGY AND TECHNOLOGY

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2016 vol. 114 p. 17 - 28

0925-5214

FaEXP2 encodes a fruit-specific expansin  that  is known to be associated with cell  wall   loosening and  fruit sof tening  in strawberry (Fragaria x ananassa  Duch.). In  spite of  its  relevant  role in  fruit  pening, little is known about the hormonal  regulation of  this gene. In the present  study, we isolated a 650 bp fragment of the FaEXP2 gene promoter and in silico analysis   revealed the presence of cis-acting elements associated with hormones, light and stress-related  responses. With the aim of characterizing the hormonal regulation of FaEXP2 expression,  strawberry fruit were treated with plant growth regulators and changes in transcript levels were  analyzed by qPCR. FaEXP2 expression levels weresignificantly higher than control in fruit  treated  with abscisic acid (ABA), and when  the endogenous source of auxins (achenes) was removed.  In contrast, transcript accumulation was not affected by exogenous applications of gibberellic acid  (GA3),  naphtalenacetic acid (NAA), ethylene or 1-methylcyclopropene (1-MCP). Also, functional analysis of FaEXP2 gene promoter was performed by transient and permanent  strawberry transformation. Histochemical GUS staining analysis showed that the 650   bp-promoter fragment was able to drive the reporter gene expression specifically to the   receptacle and along ripening. Our results provide  new   insights   into   the   hormonal  regulation   of   FaEXP2  expression.