الفهرس 
Autophagy as a Recycling Process in The living CellOnly 14 pages are availabe for public view
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Abstract
Autophagy is an essential part of the development of most organisms. It not only recycles nutrients, but also plays a significant role in maintaining homeostasis during various phases of developmental processes in most organism. However, its role during development and ripening of the fleshy fruit has not been characterized yet. The role of autophagy process in tomato fruit identified tomato homologs for several autophagy genes, including genes involved in autophagy regulation (TOR, PI3K (VPS34)), induction (ATG1, ATG13, ATG17, ATG101), vesicle nucleation (ATG2, ATG6, ATG9, ATG27) expansion and completion (ATG3, ATG5, ATG7, ATG8, ATG10, ATG12). These genes exhibited a high degree of homology with other plant autophagy genes, indicating they are conserved during the plant evolution. RNA-Seq transcriptome analyses of tomato fruits at the breaker (onset of ripening) and fully ripe (8 days after breaker) stages of fruit ripening have been used to analyze the role and regulation of autophagy during fruit ripening process. Several autophagy genes including ATG13b, APG3, ATG5a, ATG7, ATG8a, ATG8b, ATG8d, ATG8f and ATG12 were upregulated during ripening, suggesting a role of autophagy in tomato fruit ripening.
Wild-type long shelf-life processing tomato fruit cv. Ohio8245 as the genetic background for jasmonate impaired (SlLoxB) and polyamine rich tomato genotypes (556HO) and a genetic cross between them (SAMLOX) have been utilized to evaluate the roles of jasmonate or polyamines in the fruit ripening associated autophagy process. Jasmonate reduction enhanced steady state levels several ATGs, including ATG6, ATG7, ATG8b, ATG8c, ATG8g, ATG8f, PI3K but also reduced transcript levels of ATG5a, ATG8e, and ATG13b. Enhanced spermidine/spermine had a limited effect on transcript levels of ATG and showed increase in ATG8b but decrease in ATG13b. Fruits have a simultaneous increase in spermidine/ spermine and reduction in jasmonate in the double transgenic mutant (LOXSAM) exhibited patterns similar to SAM556HO suggesting a dominant role of polyamines in determining the expression pattern of the autophagy genes.
The changes in the expression patterns of the autophagy genes have been characterized in isogenic lines having ripening mutations rin, nor, and Nr and compared them to their parental wild-type genotype to understand if the autophagy has a role in fruit ripening. These investigations were carried out in a short shelf- life salad tomato fruit from cv. Ailsa Craig and its isogenic ripening impaired tomato genotypes for rin, nor, and Nr mutants. The patterns of autophagy gene expression in Ailsa Craig were similar to that Ohio 8245 confirming a role for autophagy in tomato fruit ripening. The three ripening mutation affected patterns of ATGs expression. All ripening impairing mutations, Nr, nor and rin significantly upregulated transcript levels of the autophagy genes in B8 stage compared to WT fruits likely to maintain homeostasis during extended shelf life period.