Genetic Analysis For Fe-efficiency Trait Of Malus Xiaojinensis

Iron is an important micronutrient element of plants. Iron-deficiency chlorosis is a common disorder for many plants grown in alkaline soil, and reports have indicated that it causes consequent yield reduction. Mains xiaojinensis is a high Fe-absorption apple genotype. In the last decade, many researches have focused on the physiological and biochemical basis of iron uptake and metabolism in Mains xiaojinensis., Little is known about genetic background of the high Fe-absorption character. The objective of this study was to investigate the inheritance of the high Fe-absorption among the cross between Malus xiaojinensis (Fe deficiency resistant species) and Malus baccata (the Fe deficiency susceptible species).The ploid of 239 Fl progeny of Malus xiaojinensis X Malus baccata were identified by Ploidy Analyser and Counting number of Chromosome. Identification result showed there are 34 triploid (14.23%), 190 tetraploid (79.5%) and 7 pentploid (2.93%). Furthermore, 8 aneuploid are included (3.35%).By using two Malus genotypes Malus baccata (Fe chlorosis susceptible) and Malus xiaojinensis (Fe chlorosis tolerant) and their Fl hybrid, chlorophyll content in vitro, nutrient solution conductance, pH changes of nutrient solution, reduction capacity of Fe3+, up-root Fe-content and root Fe-content were studied under controlled environmental conditions in nutrient solution with 2 different Fe supplies as Fe EDTA (i.e. 0μM, severe Fe deficiency; 4μM, intermediate Fe deficiency;). Under both Fe deficient conditions most Fl hybrids showed an intermediate chlorosis between tolerant and susceptible parents. The tolerant parent was less affected by low Fe supply than the susceptible parent as judged from the severity of leaf chlorosis, at adequate Fe supply, hybrids and their parents did not differ in leaf chlorosis.Conductance changes of nutrient solution showed no difference between the parents, and the changes among the Fl progeny caused by the environment, it is not controlled by gene. Nutrient solution pH, Fe3+ reduction capacity, Root Fe content and up-root Fe content were significantly different in the Fe chlorosis tolerant than the susceptible parent under 4uM Fe deficient conditions, but under both Fe deficient conditions the tolerant parent had only a much higherFe3+ reduction capacity than the susceptible parent. The results indicate that Fe3+ reductionshow a better relationship to Fe efficiency. All the identified parameters of the hybrids was similar to the capacity of the parent Malus baccata, only a few Fl plants show higher capacity than that of Malus xiaojinensis at both Fe-deficient conditions. Genetics analysis on up physiological and biochemical traits showed that the inheritance of Fe deficiency tolerance of Malus xiaojinensis seems not to be simple monogenic, Heretability of each traits is not same as the other one.Correlation analysis on all the physiological and biochemical traits showed that there are a little correlation between two random traits under 4μM Fe treatment, but under 0μM Fe treatment, all the correlativity but the correlativity between chlorophyll content with other traits are significant.