Biomass production, transpiration rate and endogenous abscisic acid levels in grafts of flacca and wild-type tomato (Lycopersicon esculentum)

Biomass production, transpiration rate and endogenous abscisic acid levels in grafts of flacca and wild-type tomato (Lycopersicon esculentum)

2002

A:PS

ABA is a plant signalling-molecule that plays a key role in regulating stomatal response, stress tolerance responses, and coordinated growth of roots and shoots. Knowledge of the relationship between endogenous ABA level and plant growth is essential for improving plant growth and productivity. The wild-type tomato Rheinlands Ruhm (RR) and its flacca mutant were grafted to determine the relationship between endogenous ABA levels and biomass production. The flacca genotype is an ABA-deficient mutant, characterized by high stomatal conductance during the day or the night, high transpiration rate, marked tendency to wilt, and smaller size. Flacca scions grafted on to wild-type rootstock (Fs/Wr) exhibited higher ABA levels, lower transpiration rate, and higher water content than those of a control graft of flacca scion on flacca rootstock (Fs/Fr). Fs/Wr exhibited a lower ABA concentration, xylem exudate rate, ABA xylem-loading rate, and dry weight biomass in wild-type rootstock than in the control grafts of wild-type scion on wild-type rootstock (Ws/Wr). Flacca rootstock grafted to wild-type scion (Ws/Fr) showed a higher ABA level, xylem exudation rate, ABA xylem-loading rate, dry weight biomass and length than grafts to flacca scion (Fs/Fr). Ws/Fr did not induce significant changes in wild-type scion compared with Ws/Wr. In double grafts, flacca shoot fresh weight was significantly increased in flacca scion and wild-type scion grafted on to flacca rootstock (Fs+Ws/Fr) or wild-type rootstock (Fs+Ws/Wr). There was a significant linear relationship between biomass and ABA in scions (r=0.997, P=0.001). These results support the notion that ABA increases growth of tomato seedlings via improved stomatal control.

v.29(11):1329-1335, FUNCTIONAL PLANT BIOLOGY

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