Genetic analysis of iron chlorosis tolerance in myrobalan plum x almond-peach hybrids

Iron deficiency is responsible for enormous economical losses in a wide range of crops in the Mediterranean area. Different species vary in their susceptibility from poorly to severely affected leaf chlorosis, one of the main common symptoms for the iron deficiency. The prevention of this nutritional disorder involves the use of tolerant rootstocks as the best alternative to palliate the problem in fruit tree plantations. The genetic control of the tolerance to this abiotic stress in trees is still unknown but studies in other crops suggested that it could be a quantitative trait. For that, this work is directed to understand the genetic control of iron chlorosis in tree fruits. Two approaches are being used: the quantitative genetics with detection of QTLs related with iron chlorosis and the molecular genetic approach with the search of candidates genes differentially expressed under iron deficiency. A F1 population derived from a three ways interspecific cross between the myrobalan (P. cerasifera): ‘P.2175’ and the almond x peach hybrid (P. dulcis x P. persica): Felinem (formerly GxN 22) was analyzed. SPAD measurements were performed in the leaves of the F1 individuals detecting segregation to iron chlorosis tolerance. Preliminary results showed correlation between the chlorophyll content and genomic regions located in chromosomes 2 and 6, close to other reported QTLs involved in fruit quality and fungus resistance. The candidate genes approach is being implemented based on in silico screening of genes shown to be expressed in response to iron deficiency in roots, such as those encoding FRO2, IRT1 and other candidate genes differentially expressed in grape rootstocks under iron induced chlorosis.