DROUGHT SENSITIVE 8 Affects Drought Sensitivity By Regulating Leaf Epidermal Development And Stomatal Closure In Rice

Drought is one of the major stresses that lead to a decline in rice production.In this study,a drought stress-sensitive mutant drought sensitive 8(ds8)was identified in rice(Oryza sativa L.).The leaves of ds8 showed a higher water loss rate than that of the wild type.The drought-stress test indicated that ds8 seedlings were more sensitive to drought stress than the wild type.Under drought conditions,ds8 suffered higher decline rates in agronomic traits.The result of genetic analysis indicated that the ds8 phenotype was controlled by a single recessive nuclear gene.The DS8 gene was cloned using a map-based approach.The complementation test conformed that the identity of DS8 was LOC Os08g43130.DS8 encoded a Nck-associated protein 1(NAP1)-like protein,a component of the SCAR/WAVE complex,which played a vital role in actin filament nucleation activity.A single-base substitution(G to A)was identified at the last nucleotide of the second intron in LOC Os08g43130 in ds8.This mutation caused a premature stop codon.The dysfunction of DS8 caused disordered actin filament in mutant plant.The dysfunction of DS8 damaged leaf cuticle development.The alteration in leaf epidermis increased stomatal density in ds8.On the other hand,the distorted actin filaments in the mutant led to a defect in abscisic acid(ABA)-mediated stomatal closure and increased ABA accumulation.In conclusion,DS8 encodes a NAP1-like protein that affects drought sensitivity by regulating leaf epidermal development and stomatal closure in rice.