The ALOG family members OsG1L1 and OsG1L2 regulate inflorescence branching in rice

Abstract

SUMMARY The architecture of the rice inflorescence is an important determinant of crop yield. The length of the inflorescence and the number of branches are among the key factors determining the number of spikelets, and thus grains, that a plant will develop. In particular, the timing of the identity transition from indeterminate branch meristem to determinate spikelet meristem governs the complexity of the inflorescence. In this context, the ALOG gene TAWAWA1 (TAW1) has been shown to delay the transition to determinate spikelet development in Oryza sativa (rice). Recently, by combining precise laser microdissection of inflorescence meristems with RNA‐seq, we observed that two ALOG genes, OsG1‐like 1 (OsG1L1) and OsG1L2, have expression profiles similar to that of TAW1. Here, we report that osg1l1 and osg1l2 loss‐of‐function CRISPR mutants have similar phenotypes to the phenotype of the previously published taw1 mutant, suggesting that these genes might act on related pathways during inflorescence development. Transcriptome analysis of the osg1l2 mutant suggested interactions of OsG1L2 with other known inflorescence architecture regulators and the data sets were used for the construction of a gene regulatory network (GRN), proposing interactions among genes potentially involved in controlling inflorescence development in rice. In this GRN, we selected the homeodomain‐leucine zipper transcription factor encoding the gene OsHOX14 for further characterization. The spatiotemporal expression profiling and phenotypical analysis of CRISPR loss‐of‐function mutants of OsHOX14 suggests that the proposed GRN indeed serves as a valuable resource for the identification of new proteins involved in rice inflorescence development.

Expression profiling of ALOG family genes during inflorescence development and abiotic stress responses in rice (Oryza sativa L.)

“…Among the members of the ALOG family in rice, OsG1L1 / 2 / 5 / 6 had been reported to be involved in the regulation of rice reproductive development. The mutant plants of OsG1L1 / 2, osg1l1 / osg1l2, developed panicles that were shorter, with fewer primary branch meristems (PBMs), extremely reduced secondary branch meristems (SBMs) and fewer spikelets than the wild-type plants ( Beretta et al, 2023 ). In the dominant gain-of-function mutant tawawa1-D (the mutant plant of OsG1L5 ), the activity of the inflorescence meristem (IM) was extended and spikelet specification was delayed, resulting in prolonged branch formation and increased numbers of spikelets ( Yoshida et al, 2013 ).…”

African rice (Oryza glaberrima) genomic introgressions impacting upon panicle architecture in Asian rice (O. sativa) lead to the identification of key QTLs

“…OsHOX14 (LOC_Os07g39320/Os07g0581700) encodes a protein of the Homeodomain-leucine zipper (HD-Zip) TF family and is involved in the regulation of panicle development (Beretta et al, 2023;Shao et al, 2018). Two of the identified SNPs cause amino acid variations in the coding sequence, including one in the homeobox domain (Fig.…”

“…The homeodomain-leucine zipper transcription factor gene OsHOX14 has been shown to be involved in the regulation of panicle development and its loss of function leads to a reduction in PBN compared to wild type (Shao et al, 2018;Beretta et al, 2023). The second candidate gene OsMADS18, in addition to its role in flowering time promotion (Fornara et al, 2004), is known to specify inflorescence meristem identity through interaction with PANICLE PHYTOMER2 (PAP2/OsMADS34) and the two other members of the AP1/FUL subfamily, OsMADS14 and OsMADS15 (Kobayashi et al, 2012).…”

African rice (Oryza glaberrima) genomic introgressions impacting upon panicle architecture in Asian rice (O. sativa) lead to the identification of key QTLs

“…OsHOX14 (LOC_Os07g39320/Os07g0581700) encodes a protein of the Homeodomain-leucine zipper (HD-Zip) TF family and is involved in the regulation of panicle development (Beretta et al, 2023;Shao et al, 2018). Two of the identi ed SNPs cause amino acid variations in the coding sequence, including one in the homeobox domain (Fig.…”

“…Within the q_7 − 1 region, three genes have been reported to have a direct function in panicle architecture establishment. The homeodomain-leucine zipper transcription factor gene OsHOX14 has been shown to be involved in the regulation of panicle development and its loss of function leads to a reduction in PBN compared to wild type (Shao et al, 2018;Beretta et al, 2023). The second candidate gene OsMADS18, in addition to its role in owering time promotion (Fornara et al, 2004), is known to specify in orescence meristem identity through interaction with PANICLE PHYTOMER2 (PAP2/OsMADS34) and the two other members of the AP1/FUL subfamily, OsMADS14 and OsMADS15 (Kobayashi et al, 2012).…”