Quantification of major plant hormones and expression of genes involved in ABA biosynthesis and activation/deactivation during strawberry fruit development

Abstract

ABSTRACT

Contents of eight plant hormones, expression levels of enzymes related with abscisic acid (ABA) biosynthesis, and expression levels of ripening related transcription factors (TFs) were studied in a non-climacteric fruit strawberry (Fragaria × ananassa Duch, cv. Seolhyang) during the six development stages. Eight plant hormones were 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). Developmental and ripening stages were

small green (S1), green (S2), breaker (S3), pink (S4), red (S5) and fully red coloration (S6). Contents of IAA and GA4 showed the highest levels at the S1 stage and gradually decreased afterwards. The ABA content was low at the S1 to S3 stages and then increased rapidly until the S6 stage, reaching the maximum level. In contrast, the MJ content did not show significant change, while the SA content was increased gradually. The contents of JA, JA-Ile, or ET were not sufficient to be detected or not detected. The expression levels of the ABA biosynthesis genes (FaNCED1 and FaABA2), showed positive increases with the fruit ripening. On the other hand, the expression levels of the ABA degradation genes, FaCYP707A1and FaUGT75C1, were high when the ABA contents were low in the early stages of development. Among four ripening related TFs, FaMYB1, FaMYB5, FaMYB10, and FaASR, only the FaMYB10 seemed to be closely related with ripening in strawberry fruit.