TrATG5 Gene Is Involved In The Development Of Trichoderma Reesei

Autophagy is a ubiquitous non-selective degradation process which is conserved in all eukaryotic cells.It is an important pathway to maintain a well-controlled balance between anabolism and catabolism during the cell growth and development. Under some specific circumstances,such as starvation,autophagy is induced.In this process,Long-lived proteins and organelles are degraded and the resulting macromolecule components are reused in the cell development.Autophagy is a highly conserved process among yeast,fungi and mammalians.And genes related to this process are also conserved.Recent studies revealed that autophagy appears to be involved in nutrients recycling during starvation in filamentous fungi,and it has been suggested that it may also be involved in normal developmental processes.Trichoderma reesei is an important industrial strain for the cellulase and hemicellulase production.Mainly researches of T.reesei were focused on genes involved in enzymes production and regulation.The process of autophagy in T.reesei remains uncovered.In the present study,we isolated the TrATG5 gene which is a homolog of MgATG5 gene.The functional analysis of the TrATG5 gene was performed by targeted gene disruption method and the role of this gene in the developmental process was discussed.The homologue in T.reesei was isolated by blastp using the predicted amino acid sequences of MgATG5 in T.reesei database,which designated as TrATG5.The full length of TrATG5 cDNA sequence was obtained by PCR and the complementation vector was constructed for complementing theâ–³mgatg5 mutant.TrATG5 restored the colony character,sporulation and the pathogenicity of theâ–³mgatg5 mutant which indicated that the TrATG5 gene were functional homologue of MgATG5 gene.Theâ–³tratg5 mutant was generated by targeted gene disruption method. Autophagic bodies were only observed in the vacuoles of the wild type strain,while it was absent in the vacuoles of theâ–³tratg5 mutant,indicating that autophagy was blocked.The colony of theâ–³tratg5 mutant appeared significant different from the wild type strain due to the defects in sporulation.In theâ–³tratg5 mutant,the conidiophores and the differentiation of the phialides were abnormal,but the morphology of the conidia was not changed.Also theâ–³tratg5 mutant was sensitive to starvation conditions,while the sugrose utilization and the cellulase production of theâ–³tratg5 mutant were not influnced by the depletion of TrATG5 gene.Expression of GFP-ATG5 fusion protein was spot like distributed in the mycelia and the conidia.