Salinity stress accelerates abscission of tomato pedicel explants and expression of MAPK gene members

摘要

The field experiment was conducted at the Horticulture Farm, Shenyang Agricultural University of China. The seeds of Liaoyuanduoli (Solanum esculentum Mill.), a popular tomato variety in north-east China bearing an indeterminate inflorescence, were planted in March 2012. The plants were grown in a greenhouse with natural light and normal management. We collected the flower organ to study abscission in blossom period. Abnormal abscission of flowers which usually relates to some types of stress can seriously impact crop yields. Our results show that salt stress may accelerate the tomato floral organ shedding and the abscission rate. Plant MAPK cascades are complicated networks and play vital roles in stress-induced signal transduction. By pre-treatment with 100 mM PD98059 to inactivate MAPK, we found that MAPK may be involved in the salt-induced tomato floral organ abscission and act as a positive regulator of salt tolerance. Here, three pairs of primers were designed to compare the expressions of LeMAPKs treated with different salt concentrations in tomato pedicel explants by using reverse transcriptase-polymerase chain reaction. Our findings indicated that LeMAPKs were extensively involved in salt stress response. The expression of LeMAPK2 was obviously up-regulated, suggesting that LeMAPK2 might be a salt-sensitive gene and play main defense function during tomato pedicel explant abscission induced by salt stress. And LeMAPK3 might take effect in the late stage of flower abscission induced by salt stress. These results further suggest that MAPK cascades in plants had functions in signal transduction of salt stress and the expression patterns of MAPKs are complicated in tomato pedicel explants.