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Logo of bmcpsBioMed Centralsearchsubmit a manuscriptregisterthis articleBMC Plant Biology
 
BMC Plant Biol. 2012; 12: 19.
Published online Feb 13, 2012. doi:  10.1186/1471-2229-12-19
PMCID: PMC3292969
Characterization of a calcium/calmodulin-regulated SR/CAMTA gene family during tomato fruit development and ripening
Tianbao Yang,corresponding author1 Hui Peng,1 Bruce D Whitaker,1 and William S Conway1
1Food Quality Laboratory, Plant Science Institute, USDA-ARS, Beltsville 20705, MD, USA
corresponding authorCorresponding author.
Tianbao Yang: tianbao.yang/at/ars.usda.gov; Hui Peng: hui.peng/at/ars.usda.gov; Bruce D Whitaker: bruce.whitaker/at/ars.usda.gov; William S Conway: william.conway/at/ars.usda.gov
Received September 22, 2011; Accepted February 13, 2012.
Abstract
Background
Fruit ripening is a complicated development process affected by a variety of external and internal cues. It is well established that calcium treatment delays fruit ripening and senescence. However, the underlying molecular mechanisms remain unclear.
Results
Previous studies have shown that calcium/calmodulin-regulated SR/CAMTAs are important for modulation of disease resistance, cold sensitivity and wounding response in vegetative tissues. To study the possible roles of this gene family in fruit development and ripening, we cloned seven SR/CAMTAs, designated as SlSRs, from tomato, a model fruit-bearing crop. All seven genes encode polypeptides with a conserved DNA-binding domain and a calmodulin-binding site. Calmodulin specifically binds to the putative targeting site in a calcium-dependent manner. All SlSRs were highly yet differentially expressed during fruit development and ripening. Most notably, the expression of SlSR2 was scarcely detected at the mature green and breaker stages, two critical stages of fruit development and ripening; and SlSR3L and SlSR4 were expressed exclusively in fruit tissues. During the developmental span from 10 to 50 days post anthesis, the expression profiles of all seven SlSRs were dramatically altered in ripening mutant rin compared with wildtype fruit. By contrast, only minor alterations were noted for ripening mutant nor and Nr fruit. In addition, ethylene treatment of mature green wildtype fruit transiently stimulated expression of all SlSRs within one to two hours.
Conclusions
This study indicates that SlSR expression is influenced by both the Rin-mediated developmental network and ethylene signaling. The results suggest that calcium signaling is involved in the regulation of fruit development and ripening through calcium/calmodulin/SlSR interactions.
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