Hd1,Ghd7,and DTH8 synergistically determine the rice heading date and yield-related agronomic traits

Heading date determines the seasonal and regional adaptation of rice(Oryza sativa L.)varieties and is mainly controlled by photoperiod sensitivity(PS).The core heading date genes Hd1,Ghd7,DTH8,and PRR37 act synergistically in regulating the PS.In this study,we systematically analyze the heading date,PS,and agronomic traits of eight homozygous lines with various combinations of Hd1,Ghd7,and DTH8 alleles in the prr37 background under long-day(LD)and short-day(SD)conditions,respectively.We find that Hd1 alone promotes heading,regardless of the day length.However,under LDs,Hd1 suppresses flowering,in coordination with functional Ghd7 or with Ghd7 and DTH8.These loci cooperate to negatively regulate the Ehd1-Hd3 a/RFT1 pathway and delay heading.Under SDs,Hd1 competes with various heading suppressors to promote heading.Therefore,the dual function of Hd1 is vital for PS.The lines carrying Hd1 alone show reduced plant height with fewer primary and secondary branches in panicles.Lines carrying Ghd7 and DTH8(with hd1)show delayed heading and improve agronomic traits.Overall,our results reveal the regulation of rice PS flowering by the core heading date genes and their effects on agronomic traits,providing valuable information for the selection of rice varieties for adaptation to different light and temperature conditions.

Shortened snRNA promoters for efficient CRISPR/Cas-based multiplex genome editing in monocot plants

Dear Editor,CRISPR(clustered regularly interspaced short palindromic repeats)/Cas genome editing is a powerful tool for introducing specific mutations in organisms including plants.The system is composed of a nuclease such as Cas9 or Cas12a and an engineered single-guide RNA(sgRNA)incorporating a target sequence(Li et al.,2019).A Cas9/sgRNA complex recognizes its target site in the genome,resulting in a mutation at that site.

STI PCR: An efficient method for amplification and de novo synthesis of long DNA sequences

Despite continuous improvements,it is difficult to efficiently amplify large sequences from complex templates using current PCR methods.Here,we developed a suppression thermo-interlaced(STI)PCR method for the efficient and specific amplification of long DNA sequences from genomes and synthetic DNA pools.This method uses site-specific primers containing a common 50 tag to generate a stem-loop structure,thereby repressing the amplification of smaller non-specific products through PCR suppression(PS).However,large target products are less affected by PS and show enhanced amplification when the competitive amplification of non-specific products is suppressed.Furthermore,this method uses nested thermointerlaced cycling with varied temperatures to optimize strand extension of long sequences with an uneven GC distribution.The combination of these two factors in STI PCR produces a multiplier effect,markedly increasing specificity and amplification capacity.We also developed a webtool,calGC,for analyzing the GC distribution of target DNA sequences and selecting suitable thermo-cycling programs for STI PCR.Using this method,we stably amplified very long genomic fragments(up to 38 kb)from plants and human and greatly increased the length of de novo DNA synthesis,which has many applications such as cloning,expression,and targeted genomic sequencing.Our method greatly extends PCR capacity and has great potential for use in biological fields.