Harpster M H, Brummell D A, Dunsmuir P
DNA Plant Technology, 6701 San Pablo Avenue, Oakland, California 94608, USA.
Plant Physiol. 1998 Dec;118(4):1307-16. doi: 10.1104/pp.118.4.1307.
A cDNA (Cel1) encoding an endo-1,4-beta-glucanase (EGase) was isolated from ripe fruit of strawberry (Fragaria x ananassa). The deduced protein of 496 amino acids contains a presumptive signal sequence, a common feature of cell wall-localized EGases, and one potential N-glycosylation site. Southern- blot analysis of genomic DNA from F. x ananassa, an octoploid species, and that from the diploid species Fragaria vesca indicated that the Cel1 gene is a member of a divergent multigene family. In fruit, Cel1 mRNA was first detected at the white stage of development, and at the onset of ripening, coincident with anthocyanin accumulation, Cel1 mRNA abundance increased dramatically and remained high throughout ripening and subsequent fruit deterioration. In all other tissues examined, Cel1 expression was invariably absent. Antibodies raised to Cel1 protein detected a protein of 62 kD only in ripening fruit. Upon deachenation of young white fruit to remove the source of endogenous auxins, ripening, as visualized by anthocyanin accumulation, and Cel1 mRNA accumulation were both accelerated. Conversely, auxin treatment of white fruit repressed accumulation of both Cel1 mRNA and ripening. These results indicate that strawberry Cel1 is a ripening-specific and auxin-repressed EGase, which is regulated during ripening by a decline in auxin levels originating from the achenes.
从草莓（Fragaria x ananassa）成熟果实中分离出一个编码内切 - 1,4 - β - 葡聚糖酶（EGase）的cDNA（Cel1）。推导的由496个氨基酸组成的蛋白质含有一个假定的信号序列，这是细胞壁定位的EGases的共同特征，以及一个潜在的N - 糖基化位点。对八倍体物种凤梨草莓（F. x ananassa）和二倍体物种野草莓（Fragaria vesca）的基因组DNA进行Southern杂交分析表明，Cel1基因是一个不同的多基因家族的成员。在果实中，Cel1 mRNA在发育的白色阶段首次被检测到，在成熟开始时，与花青素积累同时发生，Cel1 mRNA丰度急剧增加，并在整个成熟过程及随后的果实衰老过程中保持高水平。在所有其他检测的组织中，均未检测到Cel1表达。针对Cel1蛋白产生的抗体仅在成熟果实中检测到一种62 kD的蛋白质。对幼嫩白色果实去achenation以去除内源性生长素的来源后，通过花青素积累可视化的成熟以及Cel1 mRNA积累均加速。相反，用生长素处理白色果实会抑制Cel1 mRNA积累和成熟。这些结果表明，草莓Cel1是一种成熟特异性且受生长素抑制的EGase，其在成熟过程中受来自瘦果的生长素水平下降的调节。
