Abstract
The non-miR156 targeted SBP-box gene SQUAMOSA PROMOTER BINDING PROTEIN-LIKE 8 (SPL8), plays an important role in Arabidopsis anther development, where its loss-of-function results in a semi-sterile phenotype. Fully male-sterile plants are obtained when a spl8 loss-of-function mutation is introduced into a 35S:MIR156 genetic background, thereby revealing functional redundancy between SPL8 and miR156-targeted SBP-box genes. Here, we show that BIM1, a gene encoding a bHLH protein involved in brassinosteroid signaling and embryonic patterning, functions redundantly with SPL8 in its requirement for male fertility. Although bim1 single mutants displayed a mild fertility problem due to shortened filaments in some flowers, mutation of BIM1 significantly enhanced the semi-sterile phenotype of the spl8 mutant. Expression of both SPL8 and BIM1 was detected in overlapping expression domains during early anther developmental stages. Our data suggest that in regulating anther development, SPL8 and BIM1 function cooperatively in a common complex or in synergistic pathways. Phylogenetic analysis supports the idea of an evolutionary conserved function for both genes in angiosperm anther development.
Highlights
In flowering plants, functional development of the male stamen and the female pistil is required for successful sexual reproduction and is affected by many genetic and environmental factors
We conclude that BIM1 and SQUAMOSA PROMOTER BINDING PROTEIN-LIKE 8 (SPL8) are both required for early anther development
Our results showed that the bim1 mutation enhanced the spl8 mutant phenotype with respect to anther histogenesis, suggesting that BIM1, similar to SPL8, regulates early anther development
Summary
Functional development of the male stamen and the female pistil is required for successful sexual reproduction and is affected by many genetic and environmental factors. A complete loss of pollen production in the anthers of all formed flowers is obtained when the spl mutant is combined with a 35S:MIR156 transgene that is able to down-regulate the expression of a set of miR156-targeted SBP-box genes. Such mutant transgenic plants produce fully male sterile organs with anthers lacking all four pollen sacs [12], thereby resembling the spl/nzz mutant phenotype. Brassinosteroids, a class of plant hormones [13], have recently been reported to control male fertility by regulating the expression of several key genes involved in anther and pollen development, such as SPL/NZZ, TDF1, AMS, AtMYB103 and MS1 [14]. Mutation of BIM1 in a spl mutant background significantly enhanced the spl semi-sterile phenotype, suggesting that the products of both genes act cooperatively in a common complex or via synergistic pathways to promote Arabidopsis male fertility
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
