The shoot stem cell niche, contained within the shoot apical meristem (
Improving yield by increasing the size of produce is an important selection criterion during the domestication of fruit and vegetable crops. Genes controlling meristem organization and organ formation work in concert to regulate the size of reproductive organs. In tomato,
- NSF-PAR ID:
- 10197221
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Plant Direct
- Volume:
- 3
- Issue:
- 7
- ISSN:
- 2475-4455
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Summary SAM ) is maintained in Arabidopsis by the homeodomain proteinSHOOT MERISTEMLESS (STM ).STM is a mobile protein that traffics cell‐to‐cell, presumably through plasmodesmata. In maize, theSTM homologKNOTTED 1 shows clear differences betweenmRNA and protein localization domains in theSAM . However, theSTM mRNA and protein localization domains are not obviously different in Arabidopsis, and the functional relevance ofSTM mobility is unknown. Using a non‐mobile version ofSTM (2xNLS ‐YFP ‐STM ), we show thatSTM mobility is required to suppress axillary meristem formation during embryogenesis, to maintain meristem size, and to precisely specify organ boundaries throughout development. and organ boundary genesSTM (CUP SHAPED COTYLEDON 1 ),CUC 1 andCUC 2 regulate each other during embryogenesis to establish the embryonicCUC 3SAM and to specify cotyledon boundaries, andSTM controls expression post‐embryonically at organ boundary domains. We show that organ boundary specification by correct spatial expression ofCUC CUC genes requiresSTM mobility in the meristem. Our data suggest thatSTM mobility is critical for its normal function in shoot stem cell control. -
Abstract DWARF14 (D14) is an ɑ/β‐hydrolase and receptor for the plant hormone strigolactone (SL) in angiosperms. Upon SL perception, D14 works with MORE AXILLARY GROWTH2 (MAX2) to trigger polyubiquitination and degradation of DWARF53(D53)‐type proteins in the SUPPRESSOR OF MAX2 1‐LIKE (SMXL) family. We used CRISPR‐Cas9 to generate knockout alleles of the two homoeologous
D14 genes in theNicotiana benthamiana genome. TheNbd14a,b double mutant had several phenotypes that are consistent with the loss of SL perception in other plants, including increased axillary bud outgrowth, reduced height, shortened petioles, and smaller leaves. A ratiometric fluorescent reporter system was used to monitor degradation of SMXL7 from (AtSMXL7) after transient expression inArabidopsis thaliana N. benthamiana and treatment with the strigolactone analog GR24. AtSMXL7 was degraded after treatment with GR245DS, which has the stereochemical configuration of natural SLs, as well as its enantiomer GR24ent ‐5DS. InNbd14a,b leaves, AtSMXL7 abundance was unaffected byrac ‐GR24 or either GR24 stereoisomer. Transient coexpression of AtD14 with the AtSMXL7 reporter inNbd14a,b restored the degradation response torac ‐GR24, but required an active catalytic triad. We used this platform to evaluate the ability of several AtD14 mutants that had not been characterized in plants to target AtSMXL7 for degradation. -
Summary Many plants require prolonged exposure to cold to acquire the competence to flower. The process by which cold exposure results in competence is known as vernalization. In
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FR BOG responses insig mutants, phytochrome‐deficient lines, and mutant lines for several phy‐associated factors. We quantified chlorophyll levels and examined expression of keyBOG ‐associated genes.Results Among six
sig mutants, only thesig6 mutant significantly accumulated chlorophyll afterFR BOG treatment, similar to thephyA mutant.SIG 6 appears to control protochlorophyllide accumulation by contributing to the regulation of tetrapyrrole biosynthesis associated with glutamyl‐tRNA reductase (HEMA 1) function, select phytochrome‐interacting factor genes (PIF4 andPIF6 ), andPENTA1 , which regulatesPORA mRNA translation afterFR exposure.Conclusions Regulation of
SIG6 plays a significant role in plant responses toFR exposure during theBOG response.