Clong And Expression Analysis Of NAC Transcription Factors In Tomato

The NAC family is considered one of the largest plant-specific transcriptionfactors families. They function in diverse and vital physiological processes related togrowth and development, and are involved in the response to abiotic and biotic stress.NAC is a research hotpot in the current study of gene function and expressionnetwork regulation. Tomato is one of the most popular fleshy fruits and exhibits awealth of nutrition. The abundant genetic resources available make tomato anessential model system for the study of the development, ripening and senescence offleshy fruits. The characterization of NAC genes in tomato and fruit development isstill rudimentary. So isolation and further investigation of NAC genes from tomatowill be useful.In this paper, the characterization of NAC family transcription factors in tomatowas analyzed by bioinformatics method firstly.6NAC genes related to fruitdeveloment and ripening were seperated and analyzed. Gene expressions in differentorgans, development stages, fruit types and and their regulations under exogenoushormones were studied by PCR method. The role of NAC in ethylene biosynthesisand signalling response was further researched by application of the VIGS method tosilence the genes.(1) Bioinformatics analysis. A complete bioinformatics analysis of the NAC familytranscription factors in tomato was performed.74non-redundant SlNAC proteins(SlNAC1-74) were annotated into12subgroups. The structures, features andfunctions were analyzed. Six NAC genes, which were designated SNAC4–SNAC9,were chose to be the target genes by function prediction.(2) Gene expresions analysis. The expression analysis indicated that each SNAC geneexhibited a specific expression pattern in the tissues examined, and the mRNAlevels of6genes increased during ripening. In addition, all of the genes wereinvestigated to determine their responsiveness to hormones, and the expressions ofthe SNAC gene transcripts were induced by ABA, SA and short-time (2-24h)ethylene treatment. The interactions between SNAC and RIN or Gr werediscovered in the expression study of mutants. The experimental results showed that SNAC were likely involved in the regulation of tomato fruit development andripening in ethylene pathway.(3) VIGS research analysis. TRV-SNAC vectors were successfully constructed.Syringe infiltration method of VIGS was applied to silence the genes ofSNAC4/5/6/7/9in tomato fruit. The TRV-SNAC VIGS fruit significantlydeveloped green color phenotypes delaying fruit mature. Dissection of silencedareas for QPCR analysis identified that silencing of SNAC genes repressedexpressions of LeACS2, LeEIL and NR, and induced LeERF and LeRIN expression.All the gene expressions were inhibited with SNAC9silencing. Taken together,these results indicated that a mechanism link existed between SNAC andbiosynthesis, perception and signal transduction of ethylene. SNAC transcriptionfactor controled ethylene-regulated fruit ripening in tomato.