ABSTRACT
KEY MESSAGE: Os4BGlu14, a monolignol ß-glucosidase, plays a negative role in seed longevity by affecting primary metabolism during seed development and aging. Seed longevity is a crucial trait in agriculture and in the conservation of germplasm resources. ß-Glucosidases (BGlus) are multifunctional enzymes that affect plant growth and their adaptation to the environment. The function of rice BGlus in seed longevity, however, remains unknown. We report here that Os4BGlu14, a rice ß-Glucosidase, negatively affected seed longevity during accelerated aging. Os4BGlu14 was highly expressed in rice embryos and induced by accelerated aging. Compared to the wild type, rice lines overexpressing Os4BGlu14 had significantly greater grain length, but smaller grain width and thickness. Overexpressing (OE) lines also showed lower starch but higher glucose contents. After accelerated aging treatment, OE lines displayed a significantly lower germination percentage than the wild type. Additionally, these lines had higher lignin accumulation before and after accelerated aging. Metabolome analysis detected 217 metabolites in untreated and aged rice seeds. Comparison of the differential metabolites between WT and OE5 revealed that ten key metabolites, four of which (e.g., uridine 5'-diphosphoglucose-glucose, UDPG) were increased, while the other six (e.g., γ-aminobutyric acid and methionine) were decreased, might be the crucial factors that lead to seed deterioration. Further analysis confirmed higher UDPG levels and more severe programmed cell death in OE lines than in the wild type. Furthermore, OE lines presented a lower germination rate after abscisic acid and paclobutrazol treatment during germination, compared to the wild type. Our study provides a basis for understanding the function of Os4BGlu14 in seed longevity in rice.
Subject(s)
Oryza/genetics , Oryza/metabolism , Plant Proteins/genetics , Seeds/physiology , beta-Glucosidase/genetics , Abscisic Acid/pharmacology , Cell Death , Gene Expression Regulation, Plant , Germination/drug effects , Lignin/genetics , Lignin/metabolism , Metabolome , Oxidative Stress/physiology , Plant Cells/physiology , Plant Proteins/metabolism , Plants, Genetically Modified , Seeds/metabolism , Uridine Diphosphate Glucose/metabolism , beta-Glucosidase/metabolismABSTRACT
A F2 population containing 180 lines, which was derived from the cross between the partially sequenced indica variety "Pei'ai 64S" and the completely sequenced japonica variety "Nipponbare" , was used to construct a genetic linkage framework map (referred to as F2 map), which included 138 microsatellite sites and covered 1737.81 cM of total genomic length, an average distance of 11.90 cM. Single seed descent F2:6 population with 330 lines was used to construct a genetic linkage map (known as F6 map) using 92 markers. The total genomic length and average distance were 2563.5 cM and 27.86 cM, respectively. The F2 and F6 maps differed in linkage groups, mapped markers, sequenced order of markers, ge-netic distance and average distance on the maps. Preliminary analysis about these difference was carried out.