Miao Hongxia, Ye Zixing, da Silva Jaime A Teixeira, Qin Yonghua, Hu Guibing
State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Horticulture, South China Agricultural University, Guangzhou 510642, China.
Int J Mol Sci. 2013 Apr 17;14(4):8538-55. doi: 10.3390/ijms14048538.
Self-incompatibility (SI) is one of the important factors that can result in seedless fruit in Citrus. However, the molecular mechanism of SI in Citrus is not yet clear. In this study, two suppression subtractive hybridization (SSH) libraries (forward, F and reverse, R) were constructed to isolate differentially expressed genes in pollen from "Wuzishatangju" (SI) and "Shatangju" (self-compatibility, SC) mandarins. Four hundred and sixty-eight differentially expressed cDNA clones from 2077 positive clones were sequenced and identified. Differentially expressed ESTs are possibly involved in the SI reaction of "Wuzishatangju" by regulating pollen development, kinase activity, ubiquitin pathway, pollen-pistil interaction, and calcium ion binding. Twenty five SI candidate genes were obtained, six of which displayed specific expression patterns in various organs and stages after self- and cross-pollination. The expression level of the F-box gene (H304) and S1 (F78) in the pollen of "Wuzishatangju" was 5-fold higher than that in "Shatangju" pollen. The F-box gene, S1, UBE2, UBE3, RNaseHII, and PCP were obviously up-regulated in pistils at 3 d after self-pollination of "Wuzishatangju", approximately 3-, 2-, 10-, 5-, 5-, and 2-fold higher, respectively than that at the same stage after cross-pollination of "Wuzishatangju" × "Shatangju" pistils. The potential involvement of these genes in the pollen SI reaction of "Wuzishatangju" is discussed.
自交不亲和性（SI）是导致柑橘类果实无籽的重要因素之一。然而，柑橘自交不亲和性的分子机制尚不清楚。在本研究中，构建了两个抑制性消减杂交（SSH）文库（正向，F和反向，R），以分离“无子砂糖橘”（SI）和“砂糖橘”（自交亲和性，SC）花粉中差异表达的基因。对2077个阳性克隆中的468个差异表达的cDNA克隆进行了测序和鉴定。差异表达的ESTs可能通过调节花粉发育、激酶活性、泛素途径、花粉-雌蕊相互作用和钙离子结合参与“无子砂糖橘”的SI反应。获得了25个SI候选基因，其中6个在自花授粉和异花授粉后的不同器官和阶段表现出特异性表达模式。“无子砂糖橘”花粉中F-box基因（H304）和S1（F78）的表达水平比“砂糖橘”花粉高5倍。在“无子砂糖橘”自花授粉后3天，雌蕊中的F-box基因、S1、UBE2、UBE3、RNaseHII和PCP明显上调，分别比“无子砂糖橘”ד砂糖橘”雌蕊异花授粉后同一阶段高约3倍、2倍、10倍、5倍、5倍和2倍。讨论了这些基因在“无子砂糖橘”花粉SI反应中的潜在作用。
