Molecular cloning and characterization of a ripening-induced polygalacturonase related to papaya fruit softening

Influence of 1-methylcyclopropene on pectic enzyme activities, gene expression, and cell wall modification in papaya (Carica papayacv. ‘Sunrise’) fruit

“…1-MCP significantly reduced the rates of ethylene production at the ripe stage in fruit treated at the < 10% yellow stage ( Figure 1C), and at the ripe and over-ripe stages in fruit treated at the 25% yellow stage of maturity ( Figure 1D). These results agree with the findings of , and of , that the onset and attainment of the climacteric may be suppressed or delayed by 1-MCP, but not totally abolished, as shown by Fabi et al (2009). …”

“…P apaya (Carica papaya) is a commercially important crop whose marketable life is largely determined by the rate of ripening, and consequently softening, which is an extremely ethylene-sensitive process (Fabi et al, 2009). 1-Methylcyclopropene (1-MCP), which blocks the cellular perception of ethylene by binding competitively to receptors for the hormone (Blankenship, 2001), provides a tool with which to regulate changes during ripening that may be wholly or partially ethylenedependent (Flores et al, 2001;Moya-León et al, 2004).…”

Papaya Nutritional Analysis

“…Gene transcripts for softening-related enzymes have been identifi ed, but are ethylene dependent. Genetic techniques that inhibit ethylene or disrupt polygalacturonase and endoxylanase will delay softening, but the fruit will have an undesirable, rubbery texture (Manenoi and Paull 2007 ;Fabi et al 2009 ). Other untested possibilities include increasing vitamin C levels through over expression of a gene encoding for d -galacturonic acid reductase, as has been proposed for strawberries (Agius et al 2003 ), or increasing sugar content by controlling gene expression for sucrose synthase and acid invertase with fruit-specifi c promoters (Zhou and Paull 2001 ).…”

Mamão, uma história de sucesso

“…Fabi et al (2009a2009b) isolaram uma sequência de cDNA de uma endopoligalacturonase (endoPG) de mamão papaia. Os estudos da expressão gênica e da atividade enzimática sugeriram uma relação direta entre o aumento de transcritos e atividade da enzima endoPG e a diminuição da firmeza da polpa durante o amadurecimento.…”

“…O tratamento do mamão com 1-metilciclopropeno (1-MCP) pareceu ter inibido a enzima endoPG, e, consequentemente, a polpa não amoleceu (FABI et al, 2007(FABI et al, , 2009b. A redução na despolimerização da parede celular em frutos tratados com 1-MCP corroborou os resultados observados (SHIGA et al, 2009).…”