MoARG1, MoARG5,6 and MoARG7 involved in arginine biosynthesis are essential for growth, conidiogenesis, sexual reproduction, and pathogenicity in Magnaporthe oryzae

Abstract

Arginine is one of the most versatile amino acids in eukaryote cells, which plays important roles in a multitude of processes such as protein synthesis, nitrogen metabolism, nitric oxide (NO) and urea biosynthesis. The de novo arginine biosynthesis pathway is conserved among fungal kingdom, but poorly understood in plant pathogenic fungi. Here, we characterized the functions of three synthetic enzyme-encoding genes MoARG1, MoARG5,6, and MoARG7, which involved the seventh step, second-third step and fifth step of arginine biosynthesis in Magnaporthe oryzae, respectively. Deletion of MoARG1 or MoARG5,6, resulted in arginine auxotrophic mutants, which had a strict requirement for arginine on minimal medium (MM). Both ΔMoarg1 and ΔMoarg5,6 severely reduced in aerial hyphal growth, pigmentation, conidiogenesis, sexual reproduction and pathogenicity. Interestingly, like Saccharomyces cerevisiae, deletion of MoARG7 caused a leaky arginine auxotrophy, and attenuated pathogenicity. Limited appressorium-mediated penetration and restricted invasive hyphae growth in host cells are responsible for the severely attenuated pathogenicity of the Arg(-) mutants. Additionally, we monitored the NO generation during conidial germination and appressorial formation in both Arg(-) mutants and wild type, and demonstrated that NO generation may not occur via arginine-dependent pathway in M. oryzae. In summary, MoARG1, MoARG5,6, and MoARG7 are required for growth, conidiogenesis, sexual reproduction, and pathogenicity in M. oryzae.

Carbamoyl Phosphate Synthetase Subunit MoCpa2 Affects Development and Pathogenicity by Modulating Arginine Biosynthesis in Magnaporthe oryzae

“…Carbamoyl phosphate is produced by a branch of the de novo arginine biosynthesis pathway, and is synthesized and utilized to directly supplement ornithine (Pierard and Schroter, 1978; Davis, 1986), although the importance of arginine biosynthesis in organisms is still unknown. Zhang et al reported that three synthetic enzyme genes MoARG1, MoARG5,6 , and MoARG7 were involved in arginine biosynthesis and were required for the development and virulence of M. oryzae (Zhang et al, 2015). Therefore, further studies need to be conducted to explore the underlying mechanisms of arginine biosynthesis pathway in phytopathogens.…”

Threonine synthase CoTHR4 is involved in infection-related morphogenesis during the pre-penetration stage in Colletotrichum orbiculare

“…Amino acids, such as arginine, methionine, leucine, isoleucine and valine, are essential for hyphal growth in phytopathogenic fungi [17–19, 29]. To examine whether threonine is necessary for fungal viability, we observed hyphal growth of the cothr4 mutant on the synthetic defined (SD) media with or without threonine.…”

“…It is known that multiple amino acids, such as arginine, isoleucine, leucine and methionine, are required for conidial development in M. oryzae and Fusarium graminearum [17–19, 29]. Genome-wide gene expression profiling during conidiation in M. oryzae revealed the induction of many genes involved in amino acid transport [36].…”

“…Carbamoyl phosphate synthase MoCPA2 affects appressorium formation and penetration into the host plant by regulating arginine biosynthesis [16]. Moreover, the biosynthesis of methionine, valine, leucine and isoleucine plays critical roles in conidiation and pathogenicity, suggesting that exquisite control of amino acid biosynthesis contributes to the appropriate infection cycle of M. oryzae [17–19].…”

Transcriptomic insights into the alternative splicing‐mediated adaptation of the entomopathogenic fungus Beauveria bassiana to host niches: autophagy‐related gene 8 as an example

“…For instance, the key metabolic enzymes for arginine and lysine synthesis are alternatively spliced. In plant and human pathogens, arginine and lysine synthesis are indispensable for fungal growth and pathogenicity (Zhang et al ., , Liebmann et al ., ). In B. bassiana , carbon catabolite repression factor plays important roles in the assimilation of exogenous nutrients and fungal virulence (Luo et al ., ) and is also affected by AS processes.…”