Abstract:

To investigate the molecular mechanism underlying core browning regulation in Yali pears at different maturity stages,qRT-PCR was used to analyze the expression patterns of seven PbMYB transcription factor genes during storage in Yali pears.The complete coding sequences of PbMYB1—PbMYB7 were cloned and their transcriptional activation activities were evaluated using a yeast one-hybrid system.PbMYBs exhibited distinct temporal and maturity-specific expression profiles.Compared with those at 0 d,in early-harvested pears,PbMYB1,PbMYB4,PbMYB5,PbMYB6 and PbMYB7 were significantly up-regulated in the core at 120 d,reaching peak expression levels.In late-harvested pears,seven genes were upregulated,PbMYB2 and PbMYB3 became the predominant genes at 210 d.Mid-harvested pears showed relatively stable expression of all seven genes.At 240 d,the browning index of mid-harvested pears was the lowest(0.59),significantly lower than that of early- and late-harvested pears,and was closely correlated with the relative expression levels of the seven transcription factor genes.The full-length CDS of PbMYB1—PbMYB7 were successfully cloned,yielding fragments of 2 937,960,5 088,2 052,891,972,and 2 133 bp,respectively,as confirmed by sequencing.Self-activation assays of the seven transcription factors showed that three were successfully evaluated;PbMYB2 and PbMYB6 exhibited self-activation activity,whereas PbMYB5 did not.The self-activation of PbMYB2 and PbMYB6 suggests their potential roles as transcriptional activators,providing critical target genes for dissecting the molecular mechanisms of core browning and developing novel anti-browning germplasm.

Key words: Yali pear core, PbMYB transcription factor, Maturation, Expression pattern, Transcriptional autoactivation

CLC Number: 

• S661.2