Differential Expression of microRNAs in Maize Inbred and Hybrid Lines during Salt and Drought Stress

Here, we analyzed whether the microRNA (miRNA) expression levels differ between maize inbred lines B73 and Mo17 and their reciprocal hybrids under salt and drought stress. We found that miR156, miR164, miR166, miR168, miR171 and miR319 are differentially expressed under abiotic stress. Interestingly, Mo17 × B73 showed the strongest change in miRNA expression in response to salt or drought stress, and was also the most resilient line when under abiotic stress in terms of water loss. In summary, our findings open the possibility that differential miRNA expression levels might be involved in heightened stress tolerance in maize hybrids.

PKS5,a SNF1-related kinase,interacts with and phosphorylates NPR1,and modulates expression of WRKY38 and WRKY62

NPR1 （Nonexpressor of Pathogenesis-Related gene 1） is a major co-activator of plant defense. Phosphorylations of NPR1 play important roles in fine-tuning its activity, however a kinase corresponding to such modification remains uncharacterized. Here, we report that NPR1 interacts with PKS5 （SOS2-1ike Protein Kinase 5）. The AKR （AnKyrin Repeats） motif of NPR1 is required for this interaction. PKS5 phosphorylates NPR1 at the C-terminal region. Expression of PKS5 is induced quickly by Pseudomonas syringae pv. tomato DC3000. Expression level of two NPR1 target genes, WRKY38 and WRKY62, is reduced and/or delayed in pks5 mutants. Moreover, the expression of WRKY38 and WRKY62 displays a similar pattern in nprl-lpks5-1 double mutant comparing to that in nprl-1. Our results suggest that PKS5 functions at the upstream of NPR1 and might mediate expression of WRKY38 and WRKY62 possibly by interacting with and phosphorylating NPR 1.

Cullin-RING Ubiquitin Ligase Family in Plant Abiotic Stress Pathways

The ubiquitin-proteasome system is a key mechanism that plants use to generate adaptive responses in coping with various en- vironmental stresses. Cullin-RING （CRL） complexes represent a predominant group of ubiquitin E3 ligases in this system. In this review, we focus on the CRL E3s that have been implicated in abiotic stress signaling pathways in Arabidopsis. By comparing and analyzing these cases, we hope to gain a better understanding on how CRL complexes work under various settings in an attempt to decipher the clues about the regulatory mechanism of CRL E3s.

Exploring the genetic characteristics of 93-11 and Nipponbare recombination inbred lines based on the Golden Gate SNP assay

Understanding genetic characteristics in rice populations will facilitate exploring evolutionary mechanisms and gene cloning. Numerous molecular markers have been utilized in linkage map construction and quantitative trait locus （QTL） mappings. However, segregation-distorted markers were rarely considered, which prevented understanding genetic characteristics in many populations. In this study, we designed a 384-marker GoldenGate SNP array to genotype 283 recombination inbred lines （RILs） derived from 93-11 and Nipponbare Oryza sativa crosses. Using 294 markers that were highly polymorpbic between parents, a linkage map with a total genetic distance of 1,583.2 cM was constructed, including 231 segregation-distorted mark- ers. This linkage map was consistent with maps generated by other methods in previous studies. In total, 85 significant quanti- tative trait loci （QTLs） with phenotypic variation explained （PVE） values〉5% were identified. Among them, 34 QTLs were overlapped with reported genes/QTLs relevant to corresponding traits, and 17 QTLs were overlapped with reported sterili- ty-related genes/QTLs. Our study provides evidence that segregation-distorted markers can be used in linkage map construc- tion and QTL mapping. Moreover, genetic information resulting from this study will help us to understand recombination events and segregation distortion. Furthermore, this study will facilitate gene cloning and understanding mechanism of in- ter-subspecies hybrid sterility and correlations with important agronomic traits in rice.