2018 ASHS Annual Conference

Strawberry fruit (Fragaria × ananassa) has been considered as non-climacteric fruit. However, the roles of other major plant hormones and ripening mechanism of strawberry fruit have not been well studied clearly. To understand hormonal regulation mechanism of strawberry fruit ripening, we analyzed eight major hormones of abscisic acid (ABA), indole-3-acetic acid (IAA), gibberellin 4 (GA₄), jasmonic acid (JA), methyl-jasmonate (MJ), jasmonoyl isoleucine (JA-Ile), salicylic acid (SA) and ethylene (ET) according to strawberry fruit development stages. The quantification of hormones was conducted at six developmental stages: S1, small green; S2, green; S3, breaker; S4, pink; S5 red and S6, fully red coloration. IAA and GA₄ levels showed the highest levels at S1 stage and gradually declined during the fruit development. The level of ABA was low at from S1 to S3 stages and then rapidly increased at S6 which showed the maximum value. In contrast, the level of MJ did not significantly change during the fruit development stage. SA increased gradually during strawberry fruit ripening. JA and JA-Ile were detected but not enough to quantify as a trace amount. ET was not detected in all fruit development stages. Additionally, the ABA biosynthesis genes of FaNCED1 and FaABA2 had positive correlations with fruit ripening. The ABA degradation genes of FaCYP707A1, FaUGT75C1 encoding 8-hydroxylase had negative correlations with fruit ripening. The transcription factor expression levels of FaMYB1, FaMYB5, and FaMYB10 increased with the ripening of strawberry fruit. Therefore, the ripening of strawberry fruit would be controlled under the changes of ABA and its transcriptional regulations.