The basidiomycetous fungus Sporisorium scitamineum causes sugarcane smut that leads to severe economic losses in the major sugarcane growing areas in China, India and Brazil, etc.  Autophagy is a conserved pathway in eukaryotes for bulk degradation and cellular recycling, and was shown to be important for fungal cell growth, development, and pathogenicity.  However, physiological function of autophagy has not been studied in S. scitamineum.  In this study, we identified a conserved Atg8 protein, named as SsAtg8 and characterized its function. Our results showed that autophagy was blocked in the ssatg8Δ mutant, in nitrogen starvation.  The ssatg8Δ mutant formed pseudohypha frequently and was hypersensitive to oxidative stress.  However, mating or filamenation was unaffected in the ssatg8Δ mutant in vitro.  Overall we demonstrate that autophagy is dispensable for S. scitamineum mating/filamentation, while critical for oxidative stress tolerance and proper morphology in sporidial stage.   

Stress associated proteins (SAPs) are the A20/AN1 zinc-finger proteins which confer to abiotic stresses in plants.  In this study, TaSAP7-B, including two AN1 domains, was isolated from B genome of wheat (Triticum aestivum L.).  Sequencing analysis on TaSAP7-B illustrated one InDel (insertion-deletion) and one SNP (single nucleotide polymorphism) in the promoter region while no diversity was observed in the coding region.  On the basis of SNP in the promoter region (–260 bp), a dCAPS (derived cleaved amplified polymorphic sequences) marker SNP-260 was developed for TaSAP7-B.  Using a natural population consisting of 262 wheat accessions, significant associations were detected between the marker SNP-260 and agronomic traits, such as plant height (PH), peduncle length (PL), length of penultimate internode (LPI), number of spike per plant (NSP), and 1 000-grain weight (TGW).  Two genotypes were identified using marker SNP-260 in the natural population.  Among them, the genotypes possessing C allele exhibited a higher TGW and shorter PH than the T genotypes.  Hence, base C was considered as the superior allele.  The dCAPS marker of TaSAP7-B can be instrumental for marker-assisted selection for high grain size and short plant height.  

The stress-associated protein (SAP) multigene family is conserved in both animals and plants.  Its function in some animals and plants are known, but it is yet to be deciphered in wheat (Triticum aestivum L.).  We identified the wheat gene TaSAP17-D, a member of the SAP gene family with an AN1/AN1 conserved domain.  Subcellular localization indicated that TaSAP17-D localized to the nucleus, cytoplasm, and cell membrane.  Expression pattern analyses revealed that TaSAP17-D was highly expressed in seedlings and was involved in NaCl response, polyethylene glycol (PEG), cold, and exogenous abscisic acid (ABA).  Constitutive expression of TaSAP17-D in transgenic Arabidopsis resulted in enhanced tolerance to salt stress, confirmed by improved multiple physiological indices and significantly upregulated marker genes related to salt stress response.  Our results suggest that TaSAP17-D is a candidate gene that can be used to protect crop plants from salt stress.