An allelic variation in the promoter of the LRR-RLK gene,qSS6.1,is associated with melon seed size

Seed size is an important agronomic trait in melons that directly affects seed germination and subsequent seedling growth.However,the genetic mechanism underlying seed size in melon remains unclear.In the present study,we employed Bulked-Segregant Analysis sequencing(BSA-seq)to identify a candidate region(~1.35 Mb)on chromosome 6 that corresponds to seed size.This interval was confirmed by QTL mapping of three seed size-related traits from an F2 population across three environments.This mapping region represented nine QTLs that shared an overlapping region on chromosome 6,collectively referred to as qSS6.1.New InDel markers were developed in the qSS6.1 region,narrowing it down to a 68.35 kb interval that contains eight annotated genes.Sequence variation analysis of the eight genes identified a SNP with a C to T transition mutation in the promoter region of MELO3C014002,a leucine-rich repeat receptor-like kinase(LRR-RLK)gene.This mutation affected the promoter activity of the MELO3C014002 gene and was successfully used to differentiate the large-seeded accessions(C-allele)from the small-seeded accessions(T-allele).qRT-PCR revealed differential expression of MELO3C014002 between the two parental lines.Its predicted protein has typical LRR-RLK family domains,and phylogenetic analyses reveled its similarity with the homologs in several plant species.Altogether,these findings suggest MELO3C014002 as the most likely candidate gene involved in melon seed size regulation.Our results will be helpful for better understanding the genetic mechanism regulating seed size in melons and for genetically improving this important trait through molecular breeding pathways.

Identification of candidate genes that regulate the trade-off between seedling cold tolerance and fruit quality in melon (Cucumis melo L.)

Trade-offs between survival and growth are widely observed in plants.Melon is an annual,trailing herb that produces economically valuable fruits that are traditionally cultivated in early spring in China.Melon seedlings are sensitive to low temperatures,and thus usually suffer from cold stress during the early growth period.However,little is known about the mechanism behind the trade-offs between seedling cold tolerance and fruit quality in melon.In this study,a total of 31 primary metabolites were detected from the mature fruits of eight melon lines that differ with respect to seedling cold tolerance;these included 12 amino acids,10 organic acids,and 9 soluble sugars.Our results showed that concentrations of most of the primary metabolites in the cold-resistant melons were generally lower than in the cold-sensitive melons;the greatest difference in metabolite levels was observed between the cold-resistant line H581 and the moderately cold-resistant line HH09.The metabolite and transcriptome data for these two lines were then subjected to weighted correlation network analysis,resulting in the identification of five key candidate genes underlying the balancing between seedling cold tolerance and fruit quality.Among these genes,CmEAF7 might play multiple roles in regulating chloroplast development,photosynthesis,and the ABA pathway.Furthermore,multi-method functional analysis showed that CmEAF7 can certainly improve both seedling cold tolerance and fruit quality in melon.Our study identified an agriculturally important gene,CmEAF7,and provides a new insight into breeding methods to develop melon cultivars with seedling cold tolerance and high fruit quality.

Melon short internode(CmSi)encodes an ERECTA-like receptor kinase regulating stem elongation through auxin signaling

Plant height is one of the most important agronomic traits that directly determines plant architecture,and compact or dwarf plants can allow for increased planting density and land utilization as well as increased lodging resistance and economic yield.At least four dwarf/semidwarf genes have been identified in different melon varieties,but none of them have been cloned,and little is known about the molecular mechanisms underlying internode elongation in melon.Here,we report map-based cloning and functional characterization of the first semidwarf gene short internode(Cmsi)in melon,which encodes an ERECTA-like receptor kinase regulating internode elongation.Spatial-temporal expression analyses revealed that CmSI exhibited high expression in the vascular bundle of the main stem during internode elongation.The expression level of CmSI was positively correlated with stem length in the different melon varieties examined.Ectopic expression of CmSI in Arabidopsis and cucumber suggested CmSI as a positive regulator of internode elongation in both species.Phytohormone quantitation and transcriptome analysis showed that the auxin content and the expression levels of a number of genes involved in the auxin signaling pathway were altered in the semidwarf mutant,including several well-known auxin transporters,such as members of the ABCB family and PINFORMED genes.A melon polar auxin transport protein CmPIN2 was identified by protein–protein interaction assay as physically interacting with CmSI to modulate auxin signaling.Thus,CmSI functions in an auxin-dependent regulatory pathway to control internode elongation in melon.Our findings revealed that the ERECTA family gene CmSI regulates stem elongation in melon through auxin signaling,which can directly affect polar auxin transport.

Versatile Routing and Self-Certifying Features Support for Secure Mobility in eXpressive Internet Architecture

Integrating mobility and security in the network layer has become a key factor for Future Internet Architecture(FIA). This paper proposes a secure mobility support mechanism in e Xpressive Internet Architecture(XIA),a new FIA currently under development as part of the US National Science Foundation's(NSF) program. Utilizing the natural features of ID/locator decoupling and versatile routing in XIA, a general mechanism to support host mobility is proposed. Exploiting the self-certifying identifier, a secure binding update protocol to overcome the potential threats introduced by the proposed mobility support mechanism is also given. We demonstrate that our design in XIA outperforms IP based solutions in terms of efficiency and flexibility. We also outline our initial design to illustrate one derivative benefit of an evolvable architecture:mobility support customizability with no sacrifice of architectural generality.