Regulation of Growth, Development and Whole Organism Physiology. Reduced de-etiolation of hypocotyl growth in a tomato mutant is associated with hypersensitivity to, and high endogenous levels of, abscisic acid

Author： Fellner M.

Publisher： Oxford University Press

ISSN： 1460-2431

Source： Journal of Experimental Botany, Vol.52, Iss.357, 2001-04, pp. : 725-738

Disclaimer: Any content in publications that violate the sovereignty, the constitution or regulations of the PRC is not accepted or approved by CNPIEC.

Previous Menu Next

Abstract

A recessive single gene mutant, 7B-1, in tomato was originally selected for its photoperiod-dependent male sterility. The 7B-1 mutant also has some pleiotropic effects including reduced light-induced inhibition, i.e. de-etiolation, of the hypocotyl in long days (LD), increased seed size and weight, and reduced transpiration rate. These traits led us to investigate the sensitivity of 7B-1 to exogenous hormones and the interaction of these responses with daylength. In LD, but not in short days (SD), 7B-1 was more sensitive than wild-type (WT) to exogenous abscisic acid (ABA) for inhibition of seed germination, root elongation and transpiration rate. 7B-1 mutant also exhibited reduced responses to exogenous gibberellin (GA₃) for hypocotyl elongation, and to inhibitors of GA biosynthesis for seed germination and root and hypocotyl elongation. 7B-1 hypocotyls contained a higher level of endogenous ABA than WT in both photoperiods, although ABA levels were higher in LD than in SD. In contrast, growth-active GAs, i.e. GA₁, GA₃ and GA₄, and IAA were low in the mutant hypocotyls. The 7B-1 mutant appears to be an ABA-overproducer, and the photoperiod-regulated ABA levels may be responsible for the hypersensitivity of the mutant to exogenous ABA.