Comparative analysis of hormone levels of grape germplasms featured by different ploidies but the same genotype

Abstract

This study measured the contents of indole acetic acid (IAA), trans- and cis-abscisic acid (ABA), and cytokinins (CTKs) in the leaves and roots, which were taken from cutting seedlings of three groups of table grape germplasms featured by different ploidies but the same genotype (Tetraploid Red Earth (TRE), Tetraploid Muscat Hamburg (TMH), 2-2-4 and diploid Red Earth (RE), Muscat Hamburg (MH), 2-2-2). Results showed that in the leaves, tetraploid grapes had significantly lower IAA and ABA contents than the diploid ones; the contents of seven kinds of CTKs were significantly higher in TRE than in RE, while there were respectively eight or seven kinds of CTKs significantly lower in 2-2-4, TMH than in 2-2-2 and MH; TMH had significantly higher dihydrozeatin riboside (DHZR) content than MH. In the roots, TRE had significantly higher IAA and cis-ABA contents but lower contents of five kinds of CTKs than RE; TMH had significantly lower contents of ABA, trans-zeatin riboside (ZR), DHZR, N-6-isopentenyladenine (iP), N-6-isopentenyladenosine (iPR) but higher trans-zeatin O-glucoside (ZOG) contents than MH; 2-2-4 had significantly higher ZOG, DHZR contents but lower contents of ZR, iP, iPR than 2-2-2. Compared with the diploid grapes, the tetraploid grapes had a significantly larger average berry weight, guard cells and pollen grains, shorter internode length. Correlation analysis showed that the cis-ABA content of leaves, as well as the ZR, iPR contents of roots, were significantly negatively correlated with average berry weight, however, the trans-zeatin 7-glucoside (Z7G) and dihydrozeatin 9-glucoside (DHZ9G) contents of leaves were significantly positively correlated with it. The cis-ABA content of leaves and ZR, iP contents of roots were significantly negatively correlated with the width of pollen grains, whereas the trans-zeatin rioside O-glucoside (ZROG) content of roots was significantly negatively correlated with the length of pollen grains. The cis-ABA, DHZ9G and ZROG contents of roots were significantly negatively correlated with the width of guard cells. In short, the contents of endogenous hormones are not doubled regularly by chromosome doubling. Polyploidy is complicated; increase in the chromosome is not related to the change in endogenous hormone content. This study could serve as a reference for future research on grape ploidy breeding and cultivation physiology.