The response to exogenous abscisic acid of the roots of notabilis and its wild-type tomato under drought stress
2004
ÜNYAYAR, SERPIL | AKTOKLU, EKREM | BÜYÜKASIK, YELDA
To determine whether exogenous abscisic acid (ABA) changes the anatomy of root tissue under stress, an ABA-deficient mutant tomato, notabilis, and its wild type, the cultivar Ailsa Craig, were exposed to drought stress. Plants were grown for four weeks under controlled conditions. Then they were exposed to ABA (10<SUP>-5 </SUP>M) for 6 days under drought or well-watered conditions. Exogenous ABA and/or drought increased the number of xylem vessels in notabilis. Endodermis layer appeared clearly in drought-stressed and/or ABA-treated notabilis. Exogenous ABA increased cambium layers in wild type but drought decreased them. On the other hand, these layers were not visible clearly in ABA-applied notabilis under drought. ABA significantly induced differentiation of pith section of notabilis. The wild type already possesses sclerenchymatic pith section under normal conditions. However, sclerenchymatic pith section only formed in notabilis when ABA was applied under drought stress. It was concluded that exogenous ABA in roots of notabilis resulted in plastic anatomical structures similar to that of wild type under normal conditions and this might result in induction of resistance to soil drying.
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