Yao C, Conway W S, Ren R, Smith D, Ross G S, Sams C E
Horticultural Crops Quality Laboratory, USDA-ARS, BARC-West, Beltsville, MD 20705, USA.
Plant Mol Biol. 1999 Apr;39(6):1231-41. doi: 10.1023/a:1006155723059.
A cDNA encoding polygalacturonase-inhibiting protein (PGIP) from mature apple fruit has been cloned and characterized. The open reading frame encodes a polypeptide of 330 amino acids, in which 24 amino acids at the N-terminus comprise the signal peptide. Apple PGIP contains 10 imperfect leucine-rich repeat sequence motifs averaging 24 amino acids in length. In addition to the 1.3 kb PGIP transcript, the cloned cDNA also hybridized to RNA molecules with sizes of 3.2 and 5.0 kb. Genomic DNA analysis revealed that the apple PGIP probably belongs to a small family of genes. PGIP transcript levels varied in fruit collected at different maturities, suggesting the gene is developmentally regulated. Very high PGIP transcript levels were detected in decayed areas and the tissue adjacent to the inoculation sites of Penicillium expansum and Botrytis cinerea. However, no increase in the amount of PGIP transcript in tissue distant from the decayed region was observed. Wounding on fruit also induced PGIP gene expression but to a much lessser extent when compared with decayed areas. After storage at 0 degrees C for 1 month, the abundance of PGIP transcript in ripe fruit was substantially increased. The PGIP gene in immature and ripe fruit was rapidly up-regulated by fungal infections, while in stored fruit the induction was very limited and concurred with an increase of fruit susceptibility to fungal colonization. Since PGIP gene expression is regulated by fruit development and responds to wounding, fungal infection and cold storage, these observations suggest that apple PGIP may have multiple roles during fruit development and stress response.
已克隆并鉴定了来自成熟苹果果实的编码多聚半乳糖醛酸酶抑制蛋白（PGIP）的cDNA。开放阅读框编码一个由330个氨基酸组成的多肽，其中N端的24个氨基酸构成信号肽。苹果PGIP包含10个不完美的富含亮氨酸重复序列基序，平均长度为24个氨基酸。除了1.3 kb的PGIP转录本外，克隆的cDNA还与大小为3.2 kb和5.0 kb的RNA分子杂交。基因组DNA分析表明，苹果PGIP可能属于一个小基因家族。PGIP转录水平在不同成熟度采集的果实中有所不同，表明该基因受发育调控。在扩展青霉和灰葡萄孢腐烂区域及接种部位相邻组织中检测到非常高的PGIP转录水平。然而，在远离腐烂区域的组织中未观察到PGIP转录本数量增加。果实受伤也诱导了PGIP基因表达，但与腐烂区域相比程度要小得多。在0℃下储存1个月后，成熟果实中PGIP转录本的丰度大幅增加。未成熟和成熟果实中的PGIP基因在真菌感染后迅速上调，而在储存果实中诱导作用非常有限，且与果实对真菌定殖的易感性增加同时发生。由于PGIP基因表达受果实发育调控，并对伤口、真菌感染和冷藏有反应，这些观察结果表明苹果PGIP在果实发育和应激反应过程中可能具有多种作用。
