Jornal de Patologia Vegetal e Microbiologia

Abstrato

Correlations between Soluble Sugar and Phenol Contents in Leaves and Pear Scab Resistance

Yanbin Hua, Huangping Guo, Xin-Gen Zhou, Xiao Li, Sheng Yang, Yuqin Song, Ning Ma, Chenbo Chai, Xin Qiao and Liulin Li

Pear scab caused by Venturia nashicola is one of the most important diseases in pears in China. Better understanding of the relationships between soluble sugar and phenol contents in the leaves and pear scab will assist in developing resistant cultivars for management of this disease. However, such relationships were poorly understood. In this study, we determined soluble sugar and total phenol contents in the leaves of 29 pear cultivars with varying levels of scab resistance in May, June, August and September of 2012 and related their levels to pear scab resistance. Results of this study demonstrated that: 1) the changes in soluble sugar and total phenol contents in the leaves of interspecific pears appeared to be relatively stable in May, June and August. In September, however, significant changes in their levels were observed. The levels of soluble sugar content in the leaves of Pyrus bretschnrideri and P. communis were significantly lower. Total phenol content in the P. communis leaves reached the highest. 2) Differences in soluble sugar and total phenol contents in the leaves of pear cultivars with varying levels of scab resistance were insignificant in May, June, August, and September. Total phenol content in pear cultivars that were immune to scab was slightly higher than that in other resistant cultivars in May, June, August, and September. 3) Soluble sugar and total phenol contents in the leaves of different interspecific and scab-resistant cultivars had no significant correlations with scab incidence in May, June, August and September. 4) There was a negatively correlation (p=0.039, r=-0.386) between soluble sugar content in the leaves of different cultivars and scab incidence in August.