Determination of expression of mitogen-activated protein kinases (MAPKS) during drought stress in citrus rootstocks, sourorange, carrizo and troyer

Citrus constitute one of the widely produced and consumed fruits in the world and Turkey. Biotic and abiotic stresses are the the main factors adversly affecting the growth and development of citrus fruits. Among these stresses, drought stands out as leading problem for citrus production in the long term. Plants developed some resistance mechanisms to survive negative effects of abiotic and biotic stresses. Mitogen-Activated Protein Kinases (MAPK) plays an important role in this mechanism. MAPKs gradually activate the pathways involved in plants for growth, development, and programmed cell death, as well as abiotic stresses such as drought. In this study, first, MAPK3, 4, and 9 genes, which are known to be regulated by drought stress in other plants, were selected from citrus. The expressions of these selected MAP kinase genes during drought stress in citrus rootstocks, Sour orange, Carrizo, and Troyer citranges, which are extensively used in citrus production in Turkey were subjected to 14 days of drought stress. Leaf samples were collected at 0, 9, 12, and 14 days of drought stress and total RNA was isolated from these collected leaf samples. Then, cDNA was synthesized from these isolated RNAs using reverse transcription method. Finally, the expression levels of MAPK3, 4, and 9 genes, which are activated by drought stress, were analyzed using cDNAs and primers spesifically designed for MAPK genes by SYBR green based real-time PCR method. As a result of these analysis, changes in the expresion of MAPK genes were determined in different citrus rootstocks.