Overexpression of ACL 1 （abaxially curled leaf 1） Increased Bulliform Cells and Induced Abaxial Curling of Leaf Blades in Rice

Understanding the genetic mechanism underlying rice leaf-shape development is crucial for optimizing rice configuration and achieving high yields; however, little is known about leaf abaxial curling. We isolated a rice transferred DNA （T-DNA） insertion mutant, BY240, which exhibited an abaxial leaf curling phenotype that co-segregated with the inserted T-DNA. The T-DNA was inserted in the promoter of a novel gene, ACL1 （Abaxially Curled Leaf 1）, and led to overexpression of this gene in BY240. Overexpression of ACL1 in wild-type rice also resulted in abaxial leaf curling. ACL1 encodes a protein of 116 amino acids with no known conserved functional domains. Overexpression of ACL2, the only homolog of ACL1 in rice, also induced abaxial leaf curling. RT-PCR analysis revealed high expressions of ACLs in leaf sheaths and leaf blades, suggesting a role for these genes in leaf development. In situ hybridization revealed non-tissue-specific expression of the ACLs in the shoot apical meristem, leaf primordium, and young leaf. Histological analysis showed increased number and exaggeration of bulliform cells and expansion of epidermal cells in the leaves of BY240, which caused developmental discoordination of the abaxial and adaxial sides, resulting in abaxially curled leaves. These results revealed an important mechanism in rice leaf development and provided the genetic basis for agricultural improvement.

ZmCER1,a putative ECERIFERUM 1 protein in maize,functions in cuticular wax biosynthesis and bulliform cell development

The cuticular wax,acting as the ultimate defense barrier,is essential for the normal morphogenesis of plant organs.Despite this importance,the connection between wax composition and leaf development has not been thoroughly explored.In this study,we characterized a new maize mutant,ragged leaf4(rgd4),which exhibits crinkled and ragged leaves starting from the sixth leaf stage.The phenotype of rgd4 is conferred by ZmCER1,which encoding an aldehyde decarbonylase involved in wax biosynthesis.ZmCER1 function deficient mutant displayed reduced cuticular wax density and disordered bulliform cells(BCs),while ZmCER1 overexpressing plants exhibited the opposite effects,indicating that ZmCER1 regulates cuticular wax biosynthesis and BCs development.Additionally,as the density of cuticular wax increased,the water loss rate of detached leaf decreases,suggesting that ZmCER1 is positively correlated with plant drought tolerance.

Characterization and fine mapping of a semi-rolled leaf mutant srl3 in rice

Moderate leaf rolling can maintain leaf erectness,improve light transmittance in the population,and improve light energy utilization,thereby increasing rice yield.This study used ethyl methanesulfonate(EMS)to treat Yunjing 17(YJ17)and obtained a semi-rolled leaf mutant that was named semi-rolled leaf 3(srl3).We found that the rolled-leaf phenotype was due to the aberrant development of bulliform cells and the loss of sclerenchymatous cells.In addition,the shoot and root length of srl3 seedlings differed from the wild type.The srl3 mutant had significantly lower plant height and seed-setting rate but notably greater tiller number,panicle length,and primary branch number per panicle than the wild type.Genetic analysis showed that a single recessive nuclear gene defined the srl3 mutant,and it was precisely located in a 144-kb region between two insertion-deletion(InDel)markers,M8 and M19,on chromosome 2.In this region,no leaf-rollingrelated genes have been reported previously.Thus,the study indicated that SRL3 is a novel leaf-rolling-related gene,and the results laid the foundation for the cloning and functional analysis of the SRL3 gene.

ESCRT-Ⅲ component OsSNF7.2 modulates leaf rolling by trafficking and endosomal degradation of auxin biosynthetic enzyme OsYUC8 in rice

The endosomal sorting complex required for transport(ESCRT)is highly conserved in eukaryotic cells and plays an essential role in the biogenesis of multivesicular bodies and cargo degradation to the plant vacuole or lysosomes.Although ESCRT components affect a variety of plant growth and development processes,their impact on leaf development is rarely reported.Here,we found that OsSNF7.2,an ESCRT-Ⅲ component,controls leaf rolling in rice(Oryza sativa).The Ossnf7.2 mutant rolled leaf 17(rl17)has adaxially rolled leaves due to the decreased number and size of the bulliform cells.OsSNF7.2is expressed ubiquitously in all tissues,and its protein is localized in the endosomal compartments.OsSNF7.2 homologs,including OsSNF7,OsSNF7.3,and OsSNF7.4,can physically interact with OsSNF7.2,but their single mutation did not result in leaf rolling.Other ESCRT complex subunits,namely OsVPS20,OsVPS24,and OsBRO1,also interact with OsSNF7.2.Further assays revealed that OsSNF7.2 interacts with OsYUC8 and aids its vacuolar degradation.Both Osyuc8and rl17 Osyuc8 showed rolled leaves,indicating that OsYUC8 and OsSNF7.2 function in the same pathway,conferring leaf development.This study reveals a new biological function for the ESCRT-Ⅲcomponents,and provides new insights into the molecular mechanisms underlying leaf rolling.