ACC synthase genes related to cold-dependent ripening in pear fruit
El-Sharkawy I., Jones B., Lelièvre J.M., Pech J.C., Latchè A.
5th International Postharvest Symposium . Volume of Abstract . Verona, Italy 6-11 June 2004, p.79
2004
บทคัดย่อ
Late pear cultivars such as Passe-Crassane (PC) require a long chilling treatment before they are capable of ripening.Early cultivars such as Old Home (OH) have no cold prerequisite.
The differential regulation of 1-aminocyclopropane-1-carboxylic acid synthase (ACS) genes was studied in OH, PC and in OH x PC hybrids in order to the determine the role of this gene family in the cold requirement.Of the seven Pc-ACS cDNAs isolated, four (Pc-ACS 1a/b and Pc-ACS2a/b) showed differential expression associate with the cold requirement.Pc-ACS1a transcripts accumulated throughout the cold treatment and , with Pc-ACS2a, during ripening of cold-dependent cultivars.Pc-ACS1b and Pc-ACS2b were detected only during ripening of cold-independent genotypes.Furthermore, Pc-ACS2a transcript accumulation was negatively regulated by ethylene while Pc-ACS2b was positively regulated by the hormone.Pc-ACS3, 4 and 5 transcript accumulation was similar in all genotypes.
Genetic analysis of OH, PC, and 22 OH x PC progenies demonstrated that late, cold-dependent cultivars were homozygour for Pc-ACS1a and 2a while early, cold-independent cultivars were homozygous for Pc-ACS1(a/b) and homozygous for Pc-ACS2b.A model is presented in which differences in Pc-ACS alleles and gene expression between cold- and non-cold requiring pears are critical in determining the ripening behaviour of the cultivars.