LAZY4 acts additively with the starch-statolithdependent gravity-sensing pathway to regulate shoot gravitropism and tiller angle in rice

Rice tiller angle is a key agronomic trait that has significant effects on the establishment of a high-yield rice population.However,the molecular mechanism underlying the control of rice tiller angle remains to be clarified.Here,we characterized the novel tiller-angle gene LAZY4(LA4)in rice through map-based cloning.LA4 encodes a C3H2C3-type RING zinc-finger E3 ligase localized in the nucleus,and an in vitro ubiquitination assay revealed that the conserved RING finger domain is essential for its E3 ligase activity.We found that expression of LA4 can be induced by gravistimulation and that loss of LA4 function leads to defective shoot gravitropism caused by impaired asymmetric auxin redistribution upon gravistimulation.Genetic analysis demonstrated that LA4 acts in a distinct pathway from the starch biosynthesis regulators LA2 and LA3,which function in the starch-statolith-dependent pathway.Further genetic analysis showed that LA4 regulates shoot gravitropism and tiller angle by acting upstream of LA1 to mediate lateral auxin transport upon gravistimulation.Our studies reveal that LA4 regulates shoot gravitropism and tiller angle upstream of LA1 through a novel pathway independent of the LA2-LA3-mediated gravity-sensing mechanism,providing new insights into the rice tiller-angle regulatory network.

A heavy metal transporter gene ZmHMA3a promises safe agricultural production on cadmium-polluted arable land

In China,19%of agricultural soils contain harmful heavy metal pollutants at levels exceeding environmentally recommended standards,whilst around 3 million hectares of arable land are too polluted to grow crops on(Zhao et al.,2015;Hu et al.,2016).Among the deleterious heavy metals,cadmium(Cd)is the most bioavailable toxic metallic pollutant and is rapidly transferable through the food chain(Wang et al.,2019).Concerning the current dilemma of the enhanced food demands of a rising population and decreasing availability of arable land,it is promising to cultivate field crops that produce enough safe foods for human consumption and simultaneously remove the pollutants from contaminated arable lands.

Uncover the mystery of pleiotropic effects of PROG1 during rice domestication

Rice is one of the earliest domesticated crops,and the plant and panicle architecture are critical domesticated traits that greatly affect yield(Xu and Sun,2021).Previous studies revealed that PROSTRATE GROWTH 1(PROG1)regulates tiller angle,tiller number,and panicle architecture during rice domestication(Jin et al.,2008;Tan et al.,2008).However,the detailed molecular mechanisms through which PROG1 controls plant and panicle architecture have not yet been well documented.

LAZing around: The intricate dance of amyloplast sedimentation and gravity sensing in plants

Gravitropism,the remarkable ability of plants to adjust their growth in response to gravity,is fundamental to their existence on Earth.Pioneering research on gravitropism can date back to the work in the 1880s,notably by Charles and Francis Darwin.

The transcription factor GATA10 regulates fertility conversion of a two-line hybrid tms5 mutant rice via the modulation of UbL40 expression^∞

The thermosensitive genic male sterile 5(tms5)mutation causes thermosensitive genic male sterility in rice(Oryza sativa)through loss of RNase ZS1 function,which influences ubiquitin fusion ribosomal protein L40(UbL40)messenger RNA levels during male development.Here,we used ATAC-seq,combined with analysis of H3K9ac and H3K4me2,to identify changes in accessible chromatin during fertility conversion of the two-line hybrid rice Wux-iang S(WXS)derived from a mutant tms5 allele.Fur-thermore,RNA-seq and bioinformatic analyses identified specific transcription factors(TFs)in differentially accessible chromatin regions.Among these TFs,only GATA10 targeted UbL40.Osgata10 knockout mutations,which resulted in low expression of UbL40 and a tendency toward male fertility,confirmed that GATA10 regulated fertility conversion via themodulation of UbL40.Meanwhile,GATA10 acted as a medi-ator for interactions with ERF65,which revealed that tran-scriptional regulation is a complex process involving multiple complexes of TFs,namely TF modules.It appears that the ERF141/MADS7/MADS50/MYB modules affect metabolic processes that control anther and pollen development,es-pecially cell wall formation.Our analysis revealed that these modules directly or indirectly affect metabolic pathway-re-lated genes to coordinate plant growth with proper anther development,and furthermore,that GATA10 regulates fer-tility conversion via the modulation of UbL40 expression.