Involvement of gibberellins in the stem elongation of sun and shade ecotypes of Stellaria longipes that is induced by low light irradiance

• Published in: Plant, Cell and Environment
• Main Authors: KUREPIN, LEONID V., PHARIS, RICHARD P., REID, DAVID M., CHINNAPPA, C. C.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2006
• Subjects: Stellaria longipes
• Online Access: http://dx.doi.org/10.1111/j.1365-3040.2006.01512.x; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1365-3040.2006.01512.x; https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1365-3040.2006.01512.x

ABSTRACT Plants from two ecotypes of Stellaria longipes , alpine (an open, sunny habitat) and prairie (where adjacent plants provide a shaded habitat), were grown under normal and reduced levels of photosynthetically active radiation (PAR). Growth under low PAR is significantly promoted in both ecotypes. When quantified by the stable isotope dilution method, endogenous gibberellins (GAs) (GA 1 , GA 8 , GA 20 , GA 19 ) were significantly elevated under low PAR in both ‘sun’ and ‘shade’ ecotypes, as was GA 53 in the shade ecotype. Changes in endogenous GA 1 levels were significantly correlated with stem growth during a 28 d growth cycle and with relative growth rate (RGR) for height under low PAR for both ecotypes. Interestingly, under low irradiance PAR, changes (both increases and decreases) in GA 8 , the 2 β ‐hydroxylated ‘inactive’ catabolite of GA 1 , closely parallel bidaily stem growth changes for both ecotypes. Because the significantly greater stem elongation of both ecotypes in response to low irradiance PAR is associated with significant increases in the endogenous levels of five GAs (GA 53 , GA 19 , GA 1 , GA 8 ) in the early 13‐hydroxylation GA biosynthesis pathway (measured at days 7, 14 and 21), we conclude that the low irradiance PAR has very likely induced an overall increase in GA biosynthesis.