Transcription factor ZmNAC126 plays an important role in transcriptional regulation of maize starch synthesis-related genes

Maize(Zea mays L.)is one of the most important food crops in the world,and starch is the main component of its endosperm.Transcriptional regulation plays a vital role in starch biosynthesis.However,it is not well understood in maize.We report the identification of the transcription factor ZmNAC126 and its role in regulation of starch synthesis in maize.Transcriptional expression of ZmNAC126 was higher in maize endosperm and kernels than in roots or stems.ZmNAC126 shared a similar expression pattern with starch synthesis genes during seed development,and its expression pattern was also consistent with the accumulation of starch.ZmNAC126 is a typical transcription factor with a transactivation domain between positions 201 and 227 of the amino acid sequence,is located in the nucleus,and binds to CACG repeats in vitro.Yeast one-hybrid assay revealed that ZmNAC126 bound the promoters of ZmGBSSI,ZmSSIIa,ZmSSIV,ZmISA1,and ZmISA2.Transient overexpression of ZmNAC126 in maize endosperm increased the activities of promoters pZmSh2,pZmBt2,pZmGBSSI,pZmSSIIIa,and pZmBT1 but inhibited the activities of pZmISA1 and pZmISA2.ZmNAC126 thus acts in starch synthesis by transcriptionally regulating targeted starch synthesis-related genes in maize kernels.

Genomic Analyses Yield Markers for Identifying Agronomically Important Genes in Potato

Wild potato species have substantial phenotypic and physiological diversity. Here, we report a comprehen- sive assessment of wild and cultivated potato species based on genomic analyses of 201 accessions of Solanum section Petota. We sequenced the genomes of these 201 accessions and identified 6 487 006 high-quality single nucleotide polymorphisms （SNPs） from 167 accessions in clade 4 of Solanum section Petota, including 146 wild and 21 cultivated diploid potato accessions with a broad geographic distribution. Genome-wide genetic variation analysis showed that the diversity of wild potatoes is higher than that of cultivated potatoes, and much higher genetic diversity in the agronomically important disease resistance genes was observed in wild potatoes. Furthermore, by exploiting information about known quantitative trait loci （QTL）, we identified 609 genes under selection, including those correlated with the loss of bitterness in tubers and those involved in tuberization, two major domesticated traits of potato. Phylogenetic analyses revealed a north-south division of all species in clade 4, not just those in the S. brevicaule complex, and further supported So candolleanum as the progenitor of cultivated potato and the monophyletic origin of cultivated potato in southern Peru. In addition, we analyzed the genome of S. candolleanum and identified 529 genes lost in cultivated potato. Collectively, the molecular markers generated in this study provide a valuable resource for the identification of agronomicaUy important genes useful for potato breeding.

Microbe-derived non-necrotic glycoside hydrolase family 12 proteins act as immunogenic signatures triggering plant defenses

Plant pattern recognition receptors(PRRs)are sentinels at the cell surface sensing microbial invasion and activating innate immune responses.During infection,certain microbial apoplastic effectors can be recognized by plant PRRs,culminating in immune responses accompanied by cell death.However,the intricated relationships between the activation of immune responses and cell death are unclear.Here,we studied the glycoside hydrolase family12(GH12)protein,Ps109281,secreted by Phytophthora sojae into the plant apoplast during infection.Ps109281 exhibits xyloglucanase activity,and promotes P.sojae infection in a manner dependent on the enzyme activity.Ps109281 is recognized by the membranelocalized receptor-like protein RXEG1 and triggers immune responses in various plant species.Unlike other characterized GH12 members,Ps109281 fails to trigger cell death in plants.The loss of cell death induction activity is closely linked to a sequence polymorphism at the Nterminus.This sequence polymorphism does not affect the in planta interaction of Ps109281 with the recognition receptor RXEG1,indicating that cell death and immune response activation are determined using different regions of the GH12 proteins.Such GH12 protein also exists in other Phytophthora and fungal pathogens.Taken together,these results unravel the evolution of effector sequences underpinning different immune outputs.