Leaf morphology inheritance analysis of hybrids between 'Shatian' pumelo and citron

Abstract：【Objective】The experiment aimed to explore the genetic trend and correlation of the leaf morphological characters of the hybrids between‘Shatian'pumelo and citron C-05.【Methods】848 hybrids were obtained from the cross between the mono-embryonic female parent‘Shatian'pumelo susceptible to citrus canker disease and the mono-embryonic male parent citron C-05 resistant to citrus canker disease. 756 hybrids were chosen for the analysis. The main leaf characters including leaf length and width, petiole wing width, petiole length and leaf tip width (the width at the up 1/3 length of leaf) were analyzed. Young leaf colors were observed and scaled. Genetic variation and partial correlation analysis were performed for all the morphological traits. Genetic trends were analyzed by calculating the average, standard deviation, coefficient of variation, distribution, ultra-parents value, mid-parent value and Kurtosis, and Skewness.【Results】The leaf tip indexes of the hybrids had a significant variation, they were mostly distributed in between those of the two parents, although they were closer to that of the female parent. It seemed to be possible that the leaf tip characteristics could be influenced more by the female parent, the number of hybrids with the leaf tip index lower than that of the female accountedfor 26.3%, and those with less than the mid-parent value of the hybrids accounted for 88.03%, suggesting that the leaf tip traits would be genetically stable. The leaf shape indexes of the hybrid had a significant variation, they were mostly distributed in between those of the two parents, although they were closer to that of the female parent. It was possible that leaf shape characteristics could be influenced more by the female parent, but the number of hybrids with leaf shape indexes lower than the female accounted for 26.5%, and those with less than the mid-parent value of the hybrids accounted for 94.05%, suggesting that the leaf shape traits would be also genetically stable. The petiole wing widths of the hybrids had a significant variation, they were mostly distributed in between those of the two parents, and were closer to that of the female parent. It was likely that the petiole wing width would be mainly influenced by the female parent, but the number of hybrids with petiole wing width larger than the female accounted for 27.0%, and those with more than the mid-parent value of the hybrids accounted for 65.48%, suggesting that the petiole wing width would be genetically unstable. The petiole length of the hybrids had a significant variation, and they were mostly distributed in between the two those of the two parents accounted for 83.21%, and those with more than the mid-parent value of the hybrids accounted for 58.33%, implying that the petiole length of the hybrids tended to be vary moderately. There were 97 hybrids with green young leaves, and 659 hybrids with purple young leaves in some degrees, suggesting that the colors of young leaves would be mainly influenced by the male parent. In addition, the winged leaves were dominant to the no winged leaves, and the purple young leaves were dominant to the green young leaves. Partial correlation analysis showed that there was a very significantly positive correlation between the young leaf color and the leaf shape index, and there were very significantly negative correlations between the young leaf color and the leaf tip index, petiole wing width, and petiole length. And the leaf shape index had a significantly positive correlation with the leaf tip index, but the leaf shape index had a very significantly negative correlation with the petiole wing width.【Conclusion】In the hybrids of‘Shatian'pumelo and citron C-05, the traits of the leaf tip index, the petiole length, the leaf shape index, the petiole wing width and the young leaf color had some genetic trends and correlations, and they exhibited normal distribution, according with quantitative characters controlled by multigenes. The young leaf color characteristics could be used as morphological markers for preselection of the hybrids between‘Shatian'pumelo and citron C-05.