Natural variation of an autophagy-family gene among rice subspecies affects grain size and weight

Elucidating the genetic basis of natural variation in grain size and weight among rice varieties can help breeders develop high-yielding varieties.We identified a novel gene,GW3a(Grain Weight 3a)(LOC_Os03g27350),that affects rice grain size and weight.gw3a mutants showed higher total starch content and dry matter accumulation than the wild type(WT),Nipponbare,suggesting that GW3a negatively regulates grain size and weight.Moreover,our study found that GW3a interacted with OsATG8 by cleaving it,suggesting that GW3a may be involved in the assembly of autophagosomes and starch degradation in plants.The haplotype analysis of GW3a showed functional differences between indica and japonica rice.Taken together,we conclude that GW3a is expressed in the autophagosome pathway regulating starch metabolism in rice,affecting yield-related traits,such as grain size,grain weight and thousand grain weight(TGW).Our findings also shed new light on autophagy-mediated yield trait regulation,proposing a possible strategy for the genetic improvement of high-yield germplasm in rice.

SUPEROXIDE DISMUTASE FAMILY GENES IN WATERMELON AND THEIR RESPONSES TO DIFFERENT ABIOTIC STRESSES

Superoxide dismutase(SOD)is an important enzyme in the antioxidant system of plants and plays a vital role in stress responses by maintaining the dynamic balance of reactive oxygen species(ROS)concentrations.Genome-wide analysis of the SOD gene family in various plant species has been conducted but little is known about this gene family in watermelon(Citrullus lanatus).Here,eight SOD genes were identified in the watermelon genome and are designated Cl CSD1-5,Cl FSD1-2 and Cl MSD according to their metal cofactors.Phylogenetic analysis shows that SOD proteins from various plant species can be classified into five groups and members in the same group possess the same metal cofactor and similar subcellular localizations.Expression analysis of the Cl SOD genes indicates that they had tissue-specific expression patterns with high expression in different tissues including the leaves,flowers and fruits.In addition,the expression of Cl SOD genes differed appreciably under salinity,drought and abscisic acid(ABA)treatments,indicating that they may be involved in ROS scavenging under different abiotic stresses via an ABA-dependent signaling pathway.These results lay the foundation for elucidating the function of Cl SOD genes in stress tolerance and fruit development in watermelon.