Cloning And Expression Analyses Of β-Galactosidase And Xyloglucan Endotransglucosylase In Ziziphus Jujuba Fruit

In order to explore the molecular regulation mechanism ofβ-galactosidase (β-Gal) and xyloglucan endotransglycosylase/hydrolase (XTH) in jujube(Ziziphus jujuba Mill.)fruit, using the'Lizao'and'Zhanhua Dongzao'fruit as materials, three partialβ-Gal cDNA sequences were obtained by RT-PCR and 3'RACE, named ZJGAL1, ZJGAL2 and ZJGAL3; and two XTH cDNA sequences, named ZJXTH1 and ZJXTH2, were also obtained by the same methods. Besides, the expression of ZJGAL and ZJXTH gene during fruit growth and ripening at the room temperature were investigated by real-time quantitative PCR (RT-qPCR)approach. The main results were as follows:1. The lengths of cDNA fragaments for ZJGAL1, ZJGAL2 and ZJGAL3 are 2446bp, 2381bp and 2301bp separately. The results of Blastn Alignment in the GenBank showed that Thethe ZJGAL sequences were 71% ~ 80% identical with those of other fruit on the nucleotide sequences. The lengths of cDNA fragaments for ZJXTH1 and ZJXTH2 are both 776bp. The results of Blastn Alignment showed that the ZJXTH cDNA fragaments had 75% identity with apple (GenBank accession NO.: EU494967) and tomato (GenBank accession NO.: AY497476) and 74% identity with kiwi fruit (GenBank accession NO.:EU494954) on the nucleotide sequences.2. The real-time quantitative PCR analysis to theβ-Gal gene indicated that the ZJGAL1 and ZJGAL3 were expressed during the fruit growth and postharvest ripening and softening. We speculated that they might have some function to the cell expansion during fruit development and the postharvest softening during ripening. ZJGAL2 was mainly expressed at the postharvest ripening process, and the expression peak of the early storage coincided with the ethylene climacteric peak, we suggest that the ZJGAL2 gene mainly play some role at the postharvest ripening, and its expression may be up-regulated by the ethylene.3. The real-time quantitative PCR analysis to the XTH genes indicated that the ZJXTH genes in jujube fruit began to express since the 51 days after flowering, and the expressions during postharvest ripening were significantly higher than those of the fruit growth. We suggested that the ZJXTH genes identified mainly play some role at the postharvest ripening and promoted the color change and softening of the jujube fruit to some extent, which was much more obviously in the'Lizao'fruit.