Peptide hormones CHAL, CLL1, and CLL2 are important for stamen development in Arabidopsis

Cell-cell communication is important for normal anther development and male fertility, but little is known about signals important for this process. The polypeptide hormones CHAL/CLL1/CLL2 are redundantly required for normal stomata cell development in Arabidopsis, but the chal cll1 cll2 triple mutants exhibited reduced fertility. However, the function of the CHAL/CLL1/CLL2 genes in the regulation of Arabidopsis fertility has not been investigated. In this study, we showed that the CHAL/CLL1/CLL2 genes were highly expressed in anther filaments, tapetal cells, and male reproductive cells at anther stage 5-9. Single mutants of the CHAL/ CLL1/CLL2 genes did not show obvious fertility defects, but the double (chal cll1 and chal cll2) and triple mutants (chal cll1 cll2) showed incremental defects in fertility: short filaments, abnormal tapetal development, aborted pollens, and extremely low pollen germination rate. Further studies showed that, the expression of many anther development-required genes were obviously altered in the chal cll1 cll2 triple mutant, including BAM1, EMS1, TPD1, bHLH089, TSM1, MS1, and AMS. These data together strongly support the idea that CHAL/CLL1/CLL2 play important roles in Arabidopsis stamen development.