Cloning And Expression Analysis Of Citrus NAC Transcription Factors

NAC transcription factors, only exist in plant to play an important role in growth and development, including reproductive and vegetative organ development, formation of lateral root, transmition of auxin, tissues senescence, programmed cell death, biotic and abiotic stress responses.'Hong Anliu', a red-flesh bud sport, and its wildtype'Anliu' (Citrus sinensis [L.] Osbeck) sweet orange were selected for NAC gene cloning and transcript profiles. We aimed to exploit the relationship between NAC transcription factors and mutant appearance and to discover their potential function in fruits development and ripening. The main results are as follow:1. The homology cloning method was used to clone the citNACl gene in 'Anliu' and 'Hong Anliu'. Sequence analysis showed:citNACl had an 750bp open reading frame, encoding 249 amino acids, and it was a member of SENU5 subgroup in NAC transcription factors family; there was no base pair difference between'Hong Anliu'and 'Anliu'.2. The homology cloning method was used to clone the citNAC2 gene in'Hong Anliu'. The citNAC2 sequence had an 918bp open reading frame, encoding 305 amino acids. Sequence analysis showed that citNAC2 was a presumed allele of CsNAC, which played a role in peel pitting of citrus fruits. They belonged to the ATAF subgroup of NAC family.3. The citNAC sequence in 'Fengjie72-1' navel orange (EF185419) was used to design primers, and then cloned the citNAC gene in 'Anliu' and 'Hong Anliu'. We got the part sequence of citNAC gene, which contained 842bp and was involved in the NAP subgroup of NAC family. Compared with Fengjie72-1'navel orange, The citNAC genes of 'Anliu' and 'Hong Anliu' both had an insertion of G in the 3' end and lead to encoding more 22 amino acids.4. CitNAC and CitNACl were both senescence up-regulated genes, CitNAC might regulate the processes of mature and senescence. Both of them had a strong expression in citrus peel, the expression was increasing gradually with the process of fruit riping, the peak of expression of 'Hong Anliu' was prior to 'Anliu'. It suggested that 'Hong Anliu' was mature earlier than 'Anliu', to influence the accumulation of the carotenoids.5. CitNAC2 was highly homologous with CsNAC, both of them belonged to ATAF subgroup in NAC transcription factors family. They were disease-resistance genes, which expression could keep plant away from disease.